{"id":78893,"date":"2023-02-08T16:44:01","date_gmt":"2023-02-08T14:44:01","guid":{"rendered":"https:\/\/gahzly.com\/%d8%a3%d9%86%d8%b8%d9%85%d8%a9-%d8%a7%d9%84%d8%aa%d8%a3%d8%b1%d9%8a%d8%b6\/"},"modified":"2023-02-08T17:23:35","modified_gmt":"2023-02-08T15:23:35","slug":"gahzlys-guide-to-grounding-systems","status":"publish","type":"post","link":"https:\/\/gahzly.com\/en\/\u0645\u0642\u0627\u0644\/gahzlys-guide-to-grounding-systems\/","title":{"rendered":"Gahzly’s Guide to Grounding Systems: Types, Components, Calculations and Measurements 2023"},"content":{"rendered":"
\n

Gahzly’s Guide to Grounding Systems: Types, Components, Calculations and Measurements 2023<\/h2>\n<\/header>\n
\n

Types of grounding systems<\/span><\/span><\/span><\/span><\/h2>\n
\n
Types of grounding systems according to IEC:<\/span><\/span><\/span><\/b><\/span><\/div>\n

1) TT system <\/span><\/span><\/span>
2) it system <\/span><\/span><\/span>
3) TN system: <\/span><\/span><\/span>
\u00a0 \u00a0 \u2022 TN-C <\/span><\/span><\/span>
\u00a0 \u00a0 system \u2022 TN-S <\/span><\/span><\/span>
\u00a0 \u00a0 system \u2022 TN-CS system<\/span><\/span><\/span><\/span><\/b><\/p><\/blockquote>\n

Neutral and Bare Conductor Part Connections:<\/span><\/span><\/span><\/u><\/b><\/span><\/p>\n

\u00a0The first letter<\/span><\/span><\/span><\/span> : the relationship of the power system to grounding:<\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a0T<\/span><\/span><\/span><\/span>\u00a0<\/b> : direct neutral to grounded connection;<\/span><\/span><\/span><\/span><\/p>\n

\u00a0The first<\/span><\/span><\/span><\/span><\/b> : a neutral isolated from earthing or connected to earthing with resistance.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0The second letter<\/span><\/span><\/span><\/span> \u00a0: the relationship of the exposed conductive parts of the earthing installation:<\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a0T<\/span><\/span><\/span><\/span>\u00a0<\/b> : direct electrical connection of the exposed parts conductive to earth.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0N<\/span><\/span><\/span><\/b><\/span> : Direct electrical connection of exposed parts connected to neutral.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0N & PE Connectors Arrangement:<\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a0Suffix letter(s) (if any)<\/span><\/span><\/span><\/span><\/b>\u00a0 : Arrangement of neutral and protective conductors:<\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a0S<\/span><\/span><\/span><\/b> <\/span> : Separate neutral and protective (N & PE) conductor.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0C<\/span><\/span><\/span><\/span><\/b> : Combined neutral and protective conductor (PEN conductor).<\/span><\/span><\/span><\/span><\/p>\n

\u00a0CS<\/span><\/span><\/span><\/span><\/b> : TN-C near source, TN-S near loads.<\/span><\/span><\/span><\/span><\/p>\n

TT system<\/span><\/span><\/span><\/span><\/h3>\n

The power supply (or the neutral point of the supply transformer) is connected directly to a ground electrode, the exposed conductive parts of the consumer-side installation being grounded through a separate ground electrode that is electrically independent of the supply electrode.<\/span><\/span><\/span><\/span><\/p>\n

\"on<\/p>\n

<\/div>\n

– In the event of an insulation fault, the possibility of suddenly exposed conductive parts increases causing a dangerous condition of electric shock, and this can be avoided by using an RCD with proper sensitivity in the touch voltage function.<\/span><\/span><\/span><\/span><\/p>\n

To ensure safety conditions in the facility, the grounding values \u200b\u200bmust comply with:<\/span><\/span><\/span><\/span><\/p>\n

RA x I\u2206n \u226450V<\/span><\/span><\/span><\/span><\/span><\/span><\/p>\n

– RA = the value of the grounding resistance of the installation.<\/span><\/span><\/span><\/span><\/p>\n

– I\u2206n = residual value of the operating current of the RCD.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0Advantages of the TT system\u00a0<\/span><\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a01)<\/span><\/span><\/span><\/b> \u00a0It is the simplest grounding system to design (requiring little or no calculations), simplest to install, and requires very low maintenance.<\/span><\/span><\/span><\/span><\/div>\n

\u00a02)<\/span><\/span><\/span><\/b> Fault currents are very weekly and cannot be energized on over current protection devices and special devices (RCDs) can be used to detect the leakage current to grounding and interrupt the circuit.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0<\/span>3)<\/span><\/span><\/span><\/span><\/b> The safety of people is ensured through the use of an RCD<\/span><\/span><\/span><\/span><\/p>\n

\u00a04)<\/span><\/span><\/span><\/b> RCD can prevent fire hazard when set to\u00a0 <\/span><\/span><\/span>\u2264 500mA<\/span><\/span><\/span><\/span><\/span><\/div>\n

\u00a05)<\/span><\/span><\/span><\/b> The system can be easily extended without having to calculate lengths<\/span><\/span><\/span><\/span><\/p>\n

\n

\u00a06)<\/span><\/span><\/span><\/b>\u00a0<\/span> Faults in the medium voltage network are not transmitted to the low voltage network<\/span><\/span><\/span>
<\/span><\/p>\n

\u00a07)<\/span><\/span><\/span><\/b> Faults in the LV network are not transmitted to other LV customers.<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

\n

\u00a08)<\/span><\/span><\/span><\/b> In the event of a neutral break, the TN system does not cause any potential surge of the conductive parts exposed with the neutral conductor.<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

\u00a0Disadvantages of the TT system\u00a0<\/span><\/span><\/span><\/span><\/b><\/div>\n
\n

\u00a01)<\/span><\/span><\/span><\/b> An RCD must be installed on each outgoing line to achieve horizontal discrimination which increases the cost of the system.<\/span><\/span><\/span><\/span><\/p>\n

\u00a02)<\/span><\/span><\/span><\/b> In some cases, it is difficult to ensure vertical discrimination of the RCD.<\/span><\/span><\/span>
<\/span><\/p>\n

\u00a03)<\/span><\/span><\/span><\/b> Excess voltages may occur between all live parts and between live parts and PE conductor.<\/span><\/span><\/span><\/span><\/p>\n

\u00a04)<\/span><\/span><\/span><\/b> The safety level is subject to the grounding resistance value of the system.<\/span><\/span><\/span>
<\/span><\/p>\n<\/div>\n

\u00a0TT system applications\u00a0<\/span><\/span><\/span><\/span><\/b>\u00a0<\/span><\/p>\n

\n

 <\/p>\n

\u2022 Cottage and small industries\u00a0<\/span><\/span><\/span><\/div>\n
Utility fed installations\u00a0<\/span><\/span><\/span><\/div>\n
directly from low voltage\u00a0<\/span><\/span><\/span><\/div>\n
network.<\/span><\/span><\/span><\/div>\n

 <\/p>\n<\/div>\n

\u00a0<\/span>system it<\/span><\/span><\/span><\/span><\/span><\/h3>\n

In this system, the power supply or the neutral point of the secondary winding of the supply transformer is either isolated from grounding or connected to a ground electrode through a high amperage resistance and the exposed conductive parts of the electrical installation are connected to a separate ground electrode.<\/span><\/span><\/span><\/span><\/p>\n

\"IT<\/p>\n

<\/div>\n

– The grounding system of it does not have a direct connection between the live parts and the grounding.<\/span><\/span><\/span><\/span><\/p>\n

– In the event of an insulation failure, the value of the fault current is not high enough to generate a dangerous voltage.<\/span><\/span><\/span><\/span><\/p>\n

– On the occurrence of the first fault, protection against indirect contact shall be provided by an isolation monitor which shall provide a visual and audible alarm.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0In the event of a second fault, the service is interrupted by breakers according to the following tripping conditions:<\/span><\/span><\/span><\/span><\/p>\n

To ensure safety conditions in the facility, you must adhere to the following:<\/span><\/span><\/span><\/span><\/p>\n

RA x ID \u2264 50V<\/span><\/span><\/span><\/b><\/span><\/p>\n

– RA = the value of the grounding resistance of the installation.<\/span><\/span><\/span><\/span><\/p>\n

-id = the current value of the error for the first error.<\/span><\/span><\/span><\/span><\/p>\n

\u00a0Advantages\u00a0<\/span><\/span><\/span><\/span><\/b><\/span> of it\u00a0<\/span><\/span><\/span><\/span><\/b><\/p>\n

\u00a01)<\/span><\/span><\/span><\/b> The first fault current is too low and the first fault touch voltage is too weak<\/span><\/span><\/span><\/span><\/div>\n

\u00a02)<\/span><\/span><\/span><\/b> Optimum safety during the first mistake\u00a0<\/span><\/span><\/span><\/span><\/p>\n

\u00a03)<\/span><\/span><\/span><\/b> Low fault currents increase people’s protection and there will be no risk of electric shock.<\/span><\/span><\/span><\/span><\/div>\n

\u00a04)<\/span><\/span><\/span><\/b> When the first fault occurs, there is no need to interrupt the service and the isolation monitors issue an alarm<\/span><\/span><\/span><\/span><\/p>\n

\u00a0system defects\u00a0<\/span><\/span><\/span><\/b><\/span><\/p>\n

\u00a01)<\/span><\/span><\/span><\/b> The second fault is very large and dangerous and must be tripped using overcurrent protection devices or RCDs\u00a0<\/span><\/span><\/span><\/span><\/div>\n

2)<\/span><\/span><\/span><\/b> Dangerous touch voltage in the event of a double fault.<\/span><\/span><\/span><\/span><\/p>\n

3)<\/span><\/span><\/span><\/b> Urgent need for well-trained and qualified maintenance staff to identify faults during installation operation.<\/span><\/span><\/span><\/span><\/div>\n

4)<\/span><\/span><\/span><\/b> Network insulation should be monitored permanently.<\/span><\/span><\/span><\/span><\/p>\n

5)<\/span><\/span><\/span><\/b> High sensitivity to voltage surges from the medium voltage network.\u00a0<\/span><\/span><\/span><\/span><\/div>\n

\u00a0it\u00a0<\/span><\/span><\/span><\/span><\/b>\u00a0<\/span><\/p>\n

\n

 <\/p>\n

\u2022 Hospitals, industrial plants or utility facilities (particularly chemical, petrochemical and telecommunications) that a\u00a0<\/span><\/span><\/span><\/div>\n
Very high level of service\u00a0<\/span><\/span><\/span><\/div>\n
Continuity is required<\/span><\/span><\/span><\/div>\n
\u2022 Installations for it\u00a0<\/span><\/span><\/span><\/div>\n
Fed by UPS<\/span><\/span><\/span><\/div>\n

 <\/p>\n<\/div>\n

\u00a0TN system<\/span><\/span><\/span><\/span><\/h3>\n

In this system, the power supply (or the neutral point of the secondary winding of a supply transformer) is directly grounded at one or more points, and the exposed conductive portion of the electrical installation is connected to that point via a protective conductor (PE).<\/span><\/span><\/span><\/span><\/p>\n

– There are three types of TN systems: TN-C, TN-S and TN-CS<\/span><\/span><\/span><\/span><\/p>\n

\u00a0TN-C system<\/span><\/span><\/span><\/span><\/h3>\n

\u2022 In this system, a common conductor is used for both the neutral conductor (N) and the protective conductor (PE) all the way from the supply transformer to the consumer building, and this common conductor is called (PEN) or \u201cprotective earthing and neutral conductor\u201d<\/span><\/span><\/span><\/span><\/p>\n

\"tn-c<\/p>\n

<\/div>\n

TN-S system<\/span><\/span><\/span><\/span><\/h3>\n

\u2022 In this system, the neutral (N) and protective earth (PE) conductors are separated throughout the system from the supply transformer to the consumer’s building and are not connected at any point within the building.<\/span><\/span><\/span><\/span><\/p>\n

The separate protective earthing conductor can take the form of a metal sheath or shield for the underground supply cable.<\/span><\/span><\/span><\/span><\/p>\n

\"tn-s<\/p>\n

<\/div>\n

\u00a0TN-CS system<\/span><\/span><\/span><\/span><\/h3>\n

\u2022 Part of the system uses an integrated PEN conductor, which at some point is divided into a separate protective earth PE conductor and N neutral conductors, the integrated PEN conductor is used between the transformer or power supply and the entry point of the building while the separate conductors (PE & N) are used inside the building.<\/span><\/span><\/span><\/span><\/p>\n

This is commonly referred to as Protective Multiple Earthing (PME).<\/span><\/span><\/span><\/span><\/p>\n

\"tn-cs<\/p>\n

<\/div>\n

\u00a0Advantages of the TN system\u00a0<\/span><\/span><\/span><\/span><\/b>
<\/span><\/p>\n

\u00a01)<\/span><\/span><\/span><\/b> In the event of an insulation failure, the error or touch voltages in the TN grounding system are smaller than in the TT system, this is due to the lower voltage in the phase conductor and lower resistance of the PEN conductor compared to the TT grounding system.<\/span><\/span><\/span><\/span><\/p>\n

\u00a02)<\/span><\/span><\/span><\/b> Fault voltages are high enough to be tripped by overcurrent protection devices.<\/span><\/span><\/span><\/span><\/div>\n

\u00a0Disadvantages of the TN system\u00a0<\/span><\/span><\/span><\/b><\/span><\/span>
<\/span><\/p>\n

\u00a01)<\/span><\/span><\/span><\/b> Faults in the medium voltage network may transmit to the low voltage earthing network causing touch voltage at the consumers.<\/span><\/span><\/span><\/span><\/p>\n

\u00a02)<\/span><\/span><\/span><\/b> In the event of a neutral break, the TN system causes a potential surge of the conductive parts exposed with the neutral conductor.<\/span><\/span><\/span>
<\/span><\/p>\n

\u00a03)<\/span><\/span><\/span><\/b> Any modification in the low-voltage network leads to an increase in the resistance of the fault circuit, and therefore protection devices must be installed.<\/span><\/span><\/span><\/span><\/p>\n

\u00a04)<\/span><\/span><\/span><\/b> Low voltage network failure may cause touch voltage to other low voltage customers.<\/span><\/span><\/span><\/span><\/div>\n

\u00a0TN system applications\u00a0<\/span><\/span><\/span><\/b><\/span><\/p>\n

\n
\u00a0Industrial establishments, utilities or buildings fed by the medium voltage network.<\/span><\/span><\/span><\/div>\n<\/div>\n

grounding methods<\/span><\/span><\/span><\/span>\u00a0<\/span><\/span><\/h2>\n

Pipe grounding<\/span><\/span><\/span><\/span><\/h3>\n
\n

This is the best and most popular grounding system compared to other systems suitable for the same soil and moisture conditions. <\/span><\/span><\/span>

In this method a galvanized iron pipe of approved length and diameter is used as a ground electrode and such pipe shall have holes punched at regular intervals along the length and shall be narrow at the lower end. <\/span><\/span><\/span>

GI pipe is run vertically and straight in permanently moist soil and its size depends on the value of fault current to be conveyed and the type of soil. <\/span><\/span><\/span>

The diameter of the tube is usually 38.1 mm and the length is 2 meters for normal soils, and the length of the tube should be increased to 2.75 meters in the case of dry and rocky soils. <\/span><\/span><\/span>

The depth at which the pipe should be buried depends on the soil moisture condition.<\/span><\/span><\/span>

The lower part of the tube is surrounded by small pieces of coke or coal and salt with a thickness of not less than 15 cm around the tube. Alternate layers of coke and salt are used up to the top of the tube as the coke retains the mixture and increases the effective area of \u200b\u200bgrounding and the salt reduces the resistance to grounding. <\/span><\/span><\/span>

Another GI tube with a diameter of 19.05 mm and a length of 1.25 m (or longer) is connected at the top of the GI tube (ground electrode) with the help of a telescoping socket. <\/span><\/span><\/span>

A funnel is attached to the top of the tube with a diameter of 19.05 and the top of the tube with the funnel is placed inside a grounding hole measuring 30 cm x 30 cm x 30 cm (1 ft x 1 ft x 1 ft) and the four ends of the pit have concrete or brick walls and are covered From above with a plate of cast iron.<\/span><\/span><\/span>

During the dry summer, the grounding resistance increases due to the decrease that occurs in the watery soil, in order to increase the conductivity and obtain an effective soil. 19mm, which is further attached at the top of the GI tube. <\/span><\/span><\/span>

GI wire or strip of GI earthed wire is carried in GI tube (diameter 12 mm) at a depth of 60 cm below ground level, then this GI wire is fixed at the top of GI tube with the help of nuts and bolts. <\/span><\/span><\/span>

The cross-sectional area of \u200b\u200bthe ground wire must be sufficient to carry the fault current safely.<\/span><\/span><\/span>

<\/span><\/p>\n

\"Pipe<\/p>\n

<\/div>\n

 <\/p>\n

plate grounding<\/span><\/span><\/span><\/span>\u00a0<\/span><\/h3>\n

In this method, a plate is used as a ground electrode and the plate is made of one of the following two materials: <\/span><\/span><\/span><\/span>

1) A sheet of galvanized iron and must be at least 60 cm x 60 cm x 6.35 mm (2 ft x 2 ft x 1\/2 in) in size. <\/span><\/span><\/span><\/span>

2) a copper plate and the size shall be 60 cm x 60 cm x 3.18 mm (2 ft x 2 ft x 1\/8 in). <\/span><\/span><\/span><\/span>

In both cases, the plate shall be buried vertically in the earthing at a depth of not less than 3 m (10 feet) from the earthing level. <\/span><\/span><\/span><\/span>

Then the plate is surrounded by small pieces of coke or charcoal and salt to a thickness of at least 15 cm<\/span><\/span><\/span><\/span>

A GI pipe of 12.7 mm (1\/2 inch) diameter shall be placed horizontally 600 mm below the grounding plane and then bent to be in a vertical position up to the top of the earthing plate and into this pipe, a ground wire made of the same material as that of the grounding plate shall be carried The grounding plate (copper ground wire for copper grounding plate and GI wire for grounding plate GI) from the main grounding rod up to the top of the plate and is firmly fixed to the grounding plate with the help of bolts, nuts and washers. <\/span><\/span><\/span><\/span>

Another GI tube is placed at the top of the grounding plate and a funnel is attached at the top of this tube, the top of the tube with the funnel is placed inside a grounding hole (as above) and three or four buckets of water are poured into the funnel to maintain impedance Grounding at the lowest possible value.<\/span><\/span><\/span><\/span>

<\/span><\/p>\n

\"plate<\/p>\n

<\/div>\n

 <\/p>\n

strip or grounding wire<\/span><\/span><\/span><\/span><\/h3>\n

 <\/p>\n

This method is used in rocky areas where excavation work is very difficult.\u00a0<\/span><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

\n

In this method, strips or wires are used which can be one of the following types or shapes:<\/span><\/span><\/span><\/span><\/span><\/span><\/p>\n

    \n
  • Minimum cross-section copper strips (25 mm x 1.6 mm)<\/span><\/span><\/span><\/li>\n
  • Galvanized iron strips of minimum cross-section (25 mm x 4 mm)<\/span><\/span><\/span><\/li>\n
  • Minimum cross-section copper conductors (3 mm\u00b2)<\/span><\/span><\/span><\/li>\n
  • galvanized iron conductors of minimum cross-section (6 mm\u00b2)<\/span><\/span><\/span><\/li>\n<\/ul>\n

     <\/p>\n<\/div>\n

    \n

     <\/p>\n

    Strips or wires shall be buried in sight within the grounding at a depth of not less than 0.5 metres.<\/span><\/span><\/span><\/span><\/span><\/div>\n

    The length of the conductors or strips buried horizontally within the grounding shall not be less than 15 meters to obtain the required grounding resistance.\u00a0<\/span><\/span><\/span><\/span><\/span><\/p>\n

     <\/p>\n

    Earthing boards<\/span><\/span><\/span><\/span><\/h3>\n

    Earthing panels shall be made of electrically annealed copper sheets or steel sheets with electrolytic copper bonding<\/span><\/span><\/span>

    <\/span><\/p>\n

    Grounding plates are used where there are rocks fairly close to the grounding surface which makes it difficult to drive the grounding rods to the required depths in the soil<\/span><\/span><\/span><\/span><\/div>\n

    \u00a0Earthing panels are also used where there are highly resistive soils<\/span><\/span><\/span><\/span><\/p>\n

    \u00a0The use of grounding plates as electrodes significantly reduces the grounding resistance in stone grounding because it increases the contact area between the electrode and the grounding.<\/span><\/span><\/span><\/span><\/p>\n

    The grounding is available in dimensions of 600 mm x 600 mm and 900 mm x 900 mm and copper thickness of 1.5 mm or 3 mm.<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

    <\/div>\n

    \"Floorboards\"<\/p>\n

    grounding <\/span>network<\/span><\/span><\/span><\/span><\/span><\/strong><\/h3>\n
    \n

    The grounding network is made of copper tape of various groups, and these copper tapes are made of highly conductive copper, electrolytic copper or electroplated copper.<\/span><\/span><\/span>
    <\/span><\/p>\n


    \nEarthing mesh is often used for potential rating and is a preferred choice in telecommunication towers and other applications to reduce the risk of high steps and touch voltages that can cause problems for operators in situations such as high voltage switching.<\/span><\/span><\/span><\/span><\/p>\n


    \nEarthing mesh is used to provide a long-term, durable, and highly reliable grounding solution in high-fault current applications because it provides good grounding contact with a wide surface area of \u200b\u200bthe surrounding soil.<\/span><\/span><\/span>
    <\/span><\/p>\n


    \nThe earthing grid is available in many sizes such as (500 x 500, 600 x 600, 900 x 900, 1000 x 1000) and with a thickness of 2 mm or 3 mm.<\/span><\/span><\/span><\/span><\/p>\n


    \nThe earthing network provides high corrosion resistance, corrosion resistance and high electrical conductivity.\u00a0<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

    \"earthriver design<\/span><\/span><\/span><\/span><\/span><\/span>\u00a0<\/span><\/h3>\n

     <\/p>\n<\/div>\n

    \n

    This method is the easiest and cheapest method of grounding because it does not require any excavation work.<\/span><\/span><\/span>
    <\/span><\/p>\n

    It is suitable for sandy areas and used for temporary grounding purposes<\/span><\/span><\/span><\/span><\/p>\n

    In this method, a ground rod with a diameter of 12.7 mm (1\/2 inch), 16 mm (5\/8 inch), or 19 mm (3\/4 inch) made of galvanized steel, annealed copper, annealed copper, or stainless steel is directly pushed To manually grounded to a minimum depth of 2.44 m (8 ft) (as per NEC code)\u00a0<\/span><\/span><\/span>
    <\/span><\/p>\n

    The rod is hammered manually or with the help of a pneumatic hammer<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

    The upper end of the rod shall be kept below the level of the grounding inside an earthing hole, the four sides of which shall be concrete or brick walls and covered with a plate of cast iron.\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    The grounding conductor is installed at the top of the rod and passed into the building.<\/span><\/span><\/span><\/span><\/div>\n

    \"CeilingTypes of grounding bars\u00a0<\/span><\/span><\/span><\/span><\/h2>\n
    Types of grounding bars<\/span><\/span><\/span><\/span><\/b><\/div>\n
    \u00a01) <\/span><\/span><\/span>Solid copper grounding rods<\/span><\/span><\/span><\/u><\/span><\/span><\/b><\/div>\n
    \u00a02) <\/span><\/span><\/span><\/span>Copper-bonded steel grounding rods<\/span><\/span><\/span><\/span><\/span>\u00a0<\/u><\/span><\/b><\/div>\n
    \u00a03) <\/span><\/span><\/span>Galvanized steel grounding bars<\/span><\/span><\/span><\/u><\/span><\/span><\/b><\/div>\n
    \u00a04) <\/span><\/span><\/span>Stainless steel grounding bars<\/span><\/span><\/span><\/u><\/span>\u00a0<\/span><\/b><\/div>\n
    <\/div>\n

    Solid copper grounding bars<\/span><\/span><\/span><\/span><\/h3>\n

    It is made of extruded copper with high conductivity\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    \"with<\/p>\n

    <\/div>\n

    Advantages<\/span><\/span><\/span><\/b><\/span><\/p>\n

    It is used for soils with high moisture and salt content and is highly corrosive\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    \u00a0It is used where high fault currents are expected.<\/span><\/span><\/span><\/span><\/p>\n

    cons<\/span><\/span><\/span><\/b>\u00a0<\/b><\/span><\/p>\n

    Solid copper is a ductile metal that often flexes when driven into soil so it is not suitable for use where deep driving in earthing is required.\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    Solid copper grounding rods are quite expensive compared to other types of grounding rods<\/span><\/span><\/span><\/span><\/div>\n

    Copper bonded steel grounding rods\u00a0<\/span><\/span><\/span><\/span><\/h3>\n
    \u00a0It is made by electroplating 99.9% pure electrolytic copper (minimum thickness of 250 microns) on a low carbon, high tensile steel bar.<\/span><\/span><\/span><\/span><\/div>\n
    The copper layer is molecularly bonded to a steel rod so that it will not tear or slip when pushed into grounding.\u00a0<\/span><\/span><\/span><\/span><\/div>\n

    \"TheAdvantages<\/span><\/span><\/span><\/b><\/span><\/p>\n

    It is considered the most efficient and cost effective type of grounding rod.<\/span><\/span><\/span><\/span><\/p>\n

    It has high mechanical tensile strength and corrosion resistance at a lower cost compared to other types of grounding rods (solid copper or stainless steel).<\/span><\/span><\/span><\/span><\/p>\n

    The high mechanical tensile strength of the steel rod enables the rod to be pushed to great depths<\/span><\/span><\/span><\/span><\/div>\n

    The rod is usually treated to avoid oxidation of the copper bond.\u00a0\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    Galvanized steel grounding bars<\/span><\/span><\/span><\/span><\/h3>\n
    In this type, high tensile low carbon steel bar is hot-dipped galvanized with a layer of zinc.<\/span><\/span><\/span><\/span><\/div>\n

    The zinc coating will retard corrosion of the steel bar by providing a sacrificial barrier.<\/span><\/span><\/span><\/span><\/p>\n

    \"Galvanized<\/p>\n

    <\/div>\n

    Advantages<\/span><\/span><\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/p>\n

    It is the cheapest type of grounding rod.<\/span><\/span><\/span><\/span><\/div>\n

    It has good corrosion resistance and conductivity.\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    The conductivity of zinc is 2.5 times that of steel and is more corrosion resistant and conductive<\/span><\/span><\/span><\/span><\/div>\n

    cons<\/span><\/span><\/span><\/span><\/b>\u00a0<\/span><\/p>\n

    It has the lowest corrosion resistance\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    It has lower electrical conductivity and poor current carrying capacity.\u00a0<\/span><\/span><\/span><\/span><\/p>\n

    Applications<\/span><\/span><\/span><\/b><\/span><\/p>\n

    Galvanized steel grounding rods are suitable for use in non-critical grounding systems in temporary structures such as antennas and electrical panels on construction sites.<\/span><\/span><\/span><\/span><\/div>\n

    Stainless steel grounding bars\u00a0<\/span><\/span><\/span><\/span><\/h3>\n

    It is made of stainless steel bar<\/span><\/span><\/span><\/b><\/span><\/p>\n

    \"StainlessAdvantages<\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/p>\n

    It is used when extreme corrosion resistance and high mechanical strength are required.<\/span><\/span><\/span><\/span><\/p>\n

    The stainless steel grounding rod is treated with an oxide coating that makes it more corrosion resistant than copper.<\/span><\/span><\/span><\/span><\/p>\n

    It is used to overcome many problems caused by galvanic corrosion that can occur between dissimilar metals buried close to each other.<\/span><\/span><\/span><\/span><\/p>\n

    The stainless steel grounding rod provides high mechanical strength so it is not likely to break or bend when driven into grounding even in rocky soil.<\/span><\/span><\/span><\/span><\/p>\n

    cons<\/span><\/span><\/span><\/span>\u00a0<\/span><\/b><\/span><\/p>\n

    It is the most expensive type of grounding rod.<\/span><\/span><\/span><\/span><\/p>\n

    It has a lower electrical conductivity than other types of grounding rods.<\/span><\/span><\/span><\/span><\/div>\n

    The current carrying capacity of steel grounding rods is weak compared to copper grounding rods<\/span><\/span><\/span><\/span><\/p>\n

    Need<\/span><\/span><\/span><\/span><\/span><\/b><\/span><\/p>\n

    It is primarily used in marine\/coastal and industrial processing environments.<\/span><\/span><\/span><\/span><\/div>\n

    Earthing resistance of the grounding electrode\u00a0<\/span><\/span><\/span><\/span><\/h2>\n
    \n

    The resistance of the grounding electrode consists of three components: <\/span><\/span>\u00a01\u00a0<\/span><\/span><\/b><\/span> The resistance of the electrode itself<\/span><\/span><\/b> , which depends on the type of material it is made of and the contact resistance between the electrode and the connections to it (air wire and clamps) To keep this resistance as low as possible, the electrode must be made of a highly conductive material and must Avoid incorrect ends and fraying.<\/span><\/span><\/span>
    \u00a0<\/span><\/b>\u00a0<\/span><\/b>
    <\/span><\/p>\n

    \u00a0<\/span>\u00a02\u00a0<\/span><\/span><\/span><\/b><\/span> The contact resistance between the electrode and the grounding surrounding it is induced<\/span><\/span><\/b> , so to reduce this resistance to a negligible value, the electrode must be free of grease and coating and the soil around the electrode must be tightly packed.<\/span><\/span><\/span>\u00a0<\/span><\/b><\/span><\/p>\n

    \u00a0<\/span>\u00a03\u00a0<\/span><\/span><\/span><\/b><\/span> The resistivity of the surrounding soil<\/span><\/span><\/b> which depends on the soil composition, soil temperature and the content of the softened soil.<\/span><\/span><\/span>\u00a0<\/span><\/b><\/span><\/p>\n<\/div>\n

    <\/div>\n

    NEC grounding electrode requirements<\/span><\/span><\/span><\/span><\/h3>\n
    <\/div>\n
    According to the <\/span><\/span><\/span>NEC<\/span><\/span><\/span><\/b> , grounding electrodes consisting of plates, tubes, and rods must comply with the following:<\/span><\/span><\/span><\/span><\/div>\n

    \u00a0Pipe poles<\/span><\/span><\/span><\/span><\/b> : The pipe or channel poles must not be less than (<\/span><\/span><\/span> 3\/4 inch<\/span><\/span><\/span><\/b> ) and require corrosion protection as they are made of iron or steel.<\/span><\/span><\/span><\/span><\/p>\n

    \n
    \u00a0Plate Electrodes<\/span><\/span><\/span><\/span><\/b> : The plate electrodes shall have a surface area of \u200b\u200bnot less than<\/span><\/span><\/span> 0.186 sqm<\/span><\/span><\/span><\/b> (<\/span><\/span><\/span> 2 sq ft<\/span><\/span><\/span><\/b> ) exposed to soil when buried but a plate exposed to soil on both sides only needs<\/span><\/span><\/span> an area of \u200b\u200b0.093 sqm<\/span><\/span><\/span><\/b> (<\/span><\/span><\/span> 1 sq ft<\/span><\/span><\/span><\/b> )\u00a0<\/span><\/span><\/span><\/span><\/div>\n

    \u00a0The thickness of the electrodes made of steel or iron plate <\/span><\/span><\/span>shall be at least <\/span><\/span><\/span>6.4 mm <\/span><\/span><\/span><\/b>(in<\/span><\/span><\/b><\/span> ) but non-ferrous plate electrodes shall not be less than <\/span><\/span><\/span>1.5 mm<\/span><\/span><\/b> ( <\/span><\/span>0.06<\/span><\/span><\/b> in).<\/span><\/span><\/span><\/b><\/b><\/b><\/span><\/p>\n

    \n

    \u00a0Bar Poles<\/span><\/span><\/span><\/span><\/b> : Iron or steel bars shall not be less than<\/span><\/span><\/span> 15.87 mm<\/span><\/span><\/span><\/b> (<\/span><\/span><\/span> 5\/8<\/span><\/span><\/span><\/b> inch) in diameter and shall be galvanized to protect against corrosion.<\/span><\/span><\/span><\/span><\/p>\n

    \u00a0Stainless steel bars and non-ferrous bars such as brass or copper or equivalent shall not be less than <\/span><\/span><\/span>12.70 mm<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>\u00bd<\/span><\/span><\/span><\/b> inch) in diameter.<\/span><\/span><\/span><\/span><\/div>\n

    The rod poles must meet the following requirements: <\/span><\/span><\/span>
    \u00a01)<\/span><\/span><\/span><\/b> Their length should not be less than <\/span><\/span><\/span>1.5 meters<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>5 feet<\/span><\/span><\/span><\/b> ). <\/span><\/span><\/span>
    \u00a02)<\/span><\/span><\/span><\/b> It shall be driven, wherever possible, below the permanent level. <\/span><\/span><\/span>
    \u00a03) At least <\/span><\/span><\/span><\/b>1.8 meters<\/span><\/span><\/b> ( <\/span><\/span>6 feet<\/span><\/span><\/b><\/span> ) must be separated <\/span><\/span><\/span>from any other electrodes including those used in signal circuits, lightning system or any other purpose.<\/span><\/span><\/span><\/b><\/b><\/span><\/p>\n

    \"Gummer\u00a04)<\/span><\/span><\/span><\/b> \u00a0It must be pushed to the ground, <\/span><\/span><\/span>with a length of at least 8 feet<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>2.44 m<\/span><\/span><\/span><\/b> ) in the ground (in contact with the soil). <\/span><\/span><\/span>
    \u00a05)<\/span><\/span><\/span><\/b> \u00a0If a rocky bottom is found before the grounding rod reaches <\/span><\/span><\/span>8 feet<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>2.44 m<\/span><\/span><\/span><\/b> ) into the grounding, in this case it must be pushed into the grounding at an angle of no more than <\/span><\/span><\/span>45 degrees<\/span><\/span><\/span><\/b> from the vertical to be at least <\/span><\/span><\/span>8 feet<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>2.44 m<\/span><\/span><\/span><\/b> ) from Its length is in the ground. <\/span><\/span><\/span>
    \u00a06)<\/span><\/span><\/span><\/b> \u00a0If the rock bottom is so shallow that it is not possible to get 8 feet ( <\/span><\/span><\/span>2.44 m<\/span><\/span><\/span><\/b> ) of the rod into grounding at an angle of <\/span><\/span><\/span>45 degrees<\/span><\/span><\/span><\/b> , it is necessary to place the rod horizontally in <\/span><\/span><\/span>a 2 feet<\/span><\/span><\/span><\/b> ( <\/span><\/span><\/span>750 mm<\/span><\/span><\/span><\/b> ) deep trench.<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n<\/div>\n

    \"InstallingHow to reduce the resistance to grounding?<\/span><\/span><\/span><\/span><\/h2>\n
    If the grounding resistance is high, it can be reduced in one of the following ways: <\/span><\/span><\/span>
    \u00a01) <\/span><\/span><\/span>increasing the diameter of the grounding ro <\/span><\/span><\/span><\/u><\/span>d<\/span><\/span><\/span><\/span><\/u>
    \u00a02) <\/span><\/span><\/span>increasing the length of the grounding rod<\/span><\/span><\/span><\/span><\/u>
    \u00a03) <\/span><\/span><\/span>using multiple rods in parallel<\/span><\/span><\/span><\/span><\/u>
    \u00a04) <\/span><\/span><\/span>chemical treatment of the soil<\/span><\/span><\/span><\/span><\/u><\/b><\/span><\/div>\n

    Increase the diameter of the grounding rod<\/span><\/span><\/span><\/span><\/span><\/h3>\n
    Increasing the rod diameter has little effect on the grounding resistance.\u00a0<\/span><\/span><\/span><\/span><\/div>\n
    \n

    Doubling the diameter of the grounding rod will reduce the grounding resistance by about <\/span><\/span><\/span>10%.<\/span><\/span><\/span><\/b><\/span><\/p>\n

    \u00a0This is not a cost effective solution because doubling the diameter of the rod means an increase in the weight and cost of the rod by about 400% while the grounding resistance will only decrease by 10%.<\/span><\/span><\/span><\/div>\n<\/blockquote>\n<\/div>\n
    \u00a0<\/span>Increase the length of the grounding rod<\/span><\/span><\/span><\/span><\/div>\n
    \n

    Doubling the length of the grounding rod will reduce the grounding resistance by about <\/span><\/span><\/span>40%.<\/span><\/span><\/span><\/b><\/span><\/p>\n

    <\/div>\n<\/blockquote>\n<\/div>\n
    The following curve illustrates this effect:<\/span><\/span><\/span><\/span><\/div>\n

    \"\"Using multiple bars in parallel<\/span><\/span><\/span><\/span>\u00a0<\/span><\/h3>\n
    Multiple grounding rods driven into the grounding provide parallel paths and can effectively reduce the grounding resistance.\u00a0<\/span><\/span><\/span><\/span><\/div>\n

    NEC<\/span><\/span><\/span><\/span> requires <\/span><\/span><\/span>that a single electrode with an earth resistance greater than 25 be augmented by an additional electrode.<\/span><\/span><\/span><\/span><\/p>\n

    \n

    – If <\/span><\/span><\/span>two well spaced ground rods<\/span><\/span><\/span><\/span> (of the same size and depth) are driven into the grounding, it will reduce the total grounding resistance by about <\/span><\/span><\/span>40%<\/span><\/span><\/span><\/span><\/b>
    – If <\/span><\/span><\/span>three rods<\/span><\/span><\/span><\/span> are used , the reduction of the grounding resistance will be <\/span><\/span><\/span>60%<\/span><\/span><\/span><\/span><\/b>
    – If <\/span><\/span><\/span>four rods<\/span><\/span><\/span><\/span> are used , The reduction will be <\/span><\/span><\/span>66%.<\/span><\/span><\/span><\/span><\/b><\/p><\/blockquote>\n<\/div>\n

    The following curve illustrates this effect:<\/span><\/span><\/span><\/span><\/div>\n
    \n

    \"The<\/p>\n

     <\/p>\n<\/div>\n

    The spacing between the grounding bars<\/span><\/span><\/span><\/b><\/span><\/div>\n

    Two grounding rods must be spaced no less than the depth to which they are driven, or preferably twice the depth, and the NEC requires that the minimum spacing between two parallel rods driven into grounding be <\/span><\/span><\/span>6 feet<\/span><\/span><\/span><\/b><\/span> .<\/span><\/span><\/span><\/span><\/p>\n

    \"for<\/p>\n

    <\/div>\n

     <\/p>\n

    <\/div>\n
    The distance between the grounding rod and the building<\/span><\/span><\/span><\/b><\/span><\/div>\n
    A distance of at least <\/span><\/span><\/span>1.5 meters<\/span><\/span><\/span><\/b><\/span> must be maintained between the grounding rod and the wall of the building, and this distance is required for excavation and maintenance and to prevent back flashing if the building is not grounded.<\/span><\/span><\/span><\/span><\/div>\n
    \u00a0<\/span><\/div>\n
    The depth of the earthing conductor connects the parallel earthing bars<\/span><\/span><\/span><\/b><\/span><\/div>\n
    The horizontal earthing conductor that connects the parallel earthing bars in the grounding shall be located at a depth of not less than <\/span><\/span><\/span>50 cm<\/span><\/span><\/span><\/b><\/span> below the grounding level.<\/span><\/span><\/span><\/span><\/div>\n
    \n

    Soil resistivity measurement (Wiener method)<\/span><\/span><\/span><\/span><\/b>\u00a0<\/span><\/h3>\n
    The Wenner method<\/span><\/span><\/span><\/b> is the widely accepted method of measuring soil resistivity and was developed by Dr. Frank Wiener in 1915<\/span><\/span><\/span><\/span><\/div>\n

    \"Soilprocedures<\/span><\/span><\/span><\/u><\/span><\/b>\u00a0<\/span><\/p>\n

    \u00a01)<\/span><\/span><\/span><\/b> A four-terminal instrument such as a large grounding tester is used to measure the resistance to grounding\u00a0<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

    \u00a02)<\/span><\/span><\/span><\/b> Four micro-sized electrodes are driven down into the soil at the same depth ( <\/span><\/span><\/span>b<\/span><\/span><\/span><\/span><\/b> ) and equal distance ( <\/span><\/span><\/span>a<\/span><\/span><\/span><\/span><\/b> ) in a straight line.<\/span><\/span><\/span><\/span><\/div>\n
    Depth of electrodes <\/span><\/span><\/span>b<\/span><\/span><\/span><\/span> = 1\/3 <\/span><\/span><\/span>a<\/span><\/span><\/span><\/span><\/b><\/span><\/div>\n
    So if the electrodes are pushed to a depth of 0.3m, the distance between the electrodes must be greater than 0.91m at least<\/span><\/span><\/span><\/span><\/div>\n

    \u00a03)<\/span><\/span><\/span><\/b> Use four separate jumper wires to connect the four poles to four terminals of the device as follows:-<\/span><\/span><\/span><\/span><\/p>\n

    \n
      \n
    • The outer two electrodes (1 and 4) are connected to the terminals labeled C1 and C2 (current terminals) on the device\u00a0<\/span><\/span><\/span><\/span><\/li>\n
    • The two inner electrodes (2 and 3) are connected to the terminals labeled P1 and P2 (potential terminals) on the device\u00a0<\/span><\/span><\/span><\/span><\/li>\n<\/ul>\n<\/div>\n
      \n
      \u00a04)<\/span><\/span><\/span><\/b> \u00a0Turn on the grounding tester and then the tester injects a known current through the outer electrode (1) and return current through the grounding electrode (4) and the difference in voltage between the inner electrodes (2 and 3) is measured (V = V1 – V2) <\/span><\/span><\/span>
      indicated to V1 and V2 to a very remote point. <\/span><\/span><\/span>
      Using Ohm’s law (R = V \/ I), the grounding tester will automatically calculate the grounding resistance and its value will appear on the screen of the tester.<\/span><\/span><\/span><\/span><\/div>\n
      \"electrode\"\u00a05) Use<\/span><\/span><\/span><\/b> \u00a0the following formula to calculate the value of the grounding resistance:<\/span><\/span><\/span><\/span><\/div>\n
      \"\"\u00a0Case <\/span><\/span><\/span><\/span>in point<\/span><\/span><\/span><\/span><\/b><\/span>\u00a0<\/b>\u00a0<\/span><\/div>\n

      If the soil resistance measured by the bulky grounding tester is<\/span><\/span><\/span><\/span> 20 \u03a9\u00a0 <\/span><\/span><\/span>and the distance between the electrodes is<\/span><\/span><\/span><\/span> 3 m\u00a0 <\/span><\/span><\/span>. <\/span>Calculate the resistivity of the soil??<\/span><\/span><\/span><\/span><\/b><\/span><\/p>\n

      \n
      \u00a0Solution\u00a0<\/span><\/span><\/span><\/span><\/span><\/span><\/b><\/span><\/div>\n

       <\/p>\n

      \u00a0<\/b><\/div>\n
      \u00a0<\/b>\u03c1<\/span><\/span><\/span><\/span><\/b> \u00a0= ( <\/span><\/span><\/span>2 \u03c0 AR<\/span><\/span><\/span><\/span> )\u00a0 <\/span><\/span><\/span><\/b>= ( <\/span><\/span><\/span>2\u00a0 <\/span><\/span><\/span><\/span><\/b>\u00d7 <\/span><\/span><\/span><\/span><\/b>\u00a03.1416\u00a0 <\/span><\/span><\/span><\/span><\/b>\u00d7 <\/span><\/span><\/span><\/span><\/b>\u00a03 \u00d7 20<\/span><\/span><\/span><\/span> ) <\/span><\/span><\/span><\/b>\u00a0= 377 \u03bcm\u00a0\u00a0<\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n

       <\/p>\n<\/div>\n<\/div>\n

      <\/div>\n
      Calculation of the grounding resistance for a single ground electrode driven into the grounding<\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n

      The grounding resistance can be calculated using the following equation:<\/span><\/span><\/span><\/span><\/p>\n

      \n

      \"Calculate<\/p>\n

      <\/div>\n

      \u00a0<\/span><\/p>\n<\/div>\n

      Calculation of the total grounding resistance of several grounding electrodes being grounded<\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n

      The following equation can be used to calculate the total grounding resistance of multiple bars:<\/span><\/span><\/span><\/span><\/p>\n

      \"Calculate<\/p>\n

      <\/div>\n
      \u00a0<\/span><\/div>\n
      And F is the multiplication operator which can be determined from the following table:<\/span><\/span><\/span><\/span><\/div>\n
      \u00a0<\/span><\/div>\n

      \"Spacing<\/p>\n

      <\/div>\n
      <\/div>\n
      \u00a0Case <\/span><\/span><\/span><\/span>in point<\/span><\/span><\/span><\/span><\/b><\/span>\u00a0<\/b>\u00a0<\/span><\/div>\n

      Calculate the grounding resistance of a 3 m long, <\/span><\/span><\/span>16 mm <\/span><\/span><\/span>diameter <\/span><\/span><\/span><\/span>grounding electrode <\/span><\/span><\/span>driven into<\/span><\/span><\/span> 50 \u03bcm resistive soil <\/span><\/span>.<\/span><\/span><\/span><\/span><\/b><\/span><\/p>\n

      \n
      \u00a0Solution\u00a0<\/span><\/span><\/span><\/span><\/span><\/span><\/b><\/span><\/div>\n
      \u00a0<\/b><\/div>\n
      \u00a0 \u00a0 \u00a0 \u00a0 R = ( <\/span><\/span><\/span><\/span><\/span>\u03c1<\/span><\/span><\/span><\/span><\/span><\/span> \/ <\/span><\/span><\/span><\/span><\/span>2\u03c0 L<\/span><\/span><\/span><\/span><\/span><\/span> ) [ <\/span><\/span><\/span><\/span><\/span>ln (8L \/ d) -1<\/span><\/span><\/span><\/span><\/span><\/span> ]<\/span><\/span><\/span><\/span><\/span><\/b><\/div>\n<\/div>\n
      \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= ( <\/span><\/span><\/span>50<\/span><\/span><\/span><\/span> \/ <\/span><\/span><\/span>2\u03c0x3<\/span><\/span><\/span><\/span> ) [ <\/span><\/span><\/span>ln (8×3 \/ 0.16) -1<\/span><\/span><\/span><\/span><\/b><\/span> ]<\/span><\/span><\/span><\/b>\u00a0<\/b><\/div>\n
      = 16.75\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0<\/span><\/span><\/span><\/b><\/div>\n
      \u00a0<\/span><\/div>\n
      \n

      This is a very large value, to reduce this resistance, another rod (electrode) is pushed parallel to the first rod. <\/span><\/span><\/span>
      Hence the equivalent earthing resistance will be:<\/span><\/span><\/span>
      <\/span><\/p>\n

      new = ( <\/span><\/span><\/span>16.75<\/span><\/span><\/span><\/span> \/ <\/span><\/span><\/span>2<\/span><\/span><\/span><\/span> ) x <\/span><\/span><\/span>1.16<\/span><\/span><\/span><\/span> = 9.7<\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n<\/div>\n
      This is also a significant value and can be reduced by driving a third rod parallel to the two rods, the total grounding resistance will be:<\/span><\/span><\/span><\/span><\/div>\n
      New <\/span><\/span><\/span><\/span>R <\/span><\/span><\/span><\/span>\u00a0= ( <\/span><\/span><\/span>16.75<\/span><\/span><\/span><\/span> \/ <\/span><\/span><\/span>3<\/span><\/span><\/span><\/span> ) x <\/span><\/span><\/span>1.29<\/span><\/span><\/span><\/span> \u00a0= 7.2 ohms<\/span><\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n
      If 4 bars are used, the grounding resistance is:<\/span><\/span><\/span><\/span><\/div>\n
      New<\/span><\/span><\/span><\/span> R <\/span><\/span><\/span>\u00a0= ( <\/span><\/span><\/span>16.75<\/span><\/span><\/span><\/span> \/ <\/span><\/span><\/span>4<\/span><\/span><\/span><\/span> ) x <\/span><\/span><\/span>1.36<\/span><\/span><\/span><\/span> \u00a0= 5.6<\/span><\/span><\/span><\/b>\u00a0<\/span><\/div>\n
      <\/div>\n

      \u00a0Soil chemical treatment<\/span><\/span><\/span><\/span><\/h3>\n

      Soil chemical treatment is a good way to reduce the grounding resistance of a grounding electrode in situations where we cannot drive the electrode to deeper depths due to hard bedrock and when the use of multiple rods is impractical.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a0<\/span>1\u00a0 <\/span><\/span><\/span><\/span> Soil treatment using chemical compounds<\/span><\/span><\/span><\/span><\/b><\/div>\n
      <\/div>\n
      In this method, many chemical compounds can be used to reduce the grounding resistance of the electrode such as:\u00a0<\/span><\/span><\/span><\/span><\/div>\n
      1) <\/span><\/span><\/span>Magnesium Sulfate<\/span><\/span><\/span><\/b> (Epsom Salt) \u201cMgSO4\u201d<\/span><\/span><\/span><\/span><\/div>\n
      2) <\/span><\/span><\/span>Copper sulfate<\/span><\/span><\/span><\/b> (glass blue) “CuSO4”<\/span><\/span><\/span><\/span><\/div>\n
      3) <\/span><\/span><\/span>Calcium chloride<\/span><\/span><\/span><\/b> (salt rock) “NaCL”<\/span><\/span><\/span><\/span><\/div>\n

      Magnesium sulfate is the most widely used chemical compound because of its low cost, high electrical conductivity and least corrosive effect.<\/span><\/span><\/span><\/span><\/p>\n

      Rock salt is cheap and has excellent electrical conductivity, but it is highly corrosive and may damage nearby metal objects, so it is not a preferred chemical compound for soil treatment.\u00a0<\/span><\/span><\/span><\/span><\/div>\n

      Synthesis of chemical compounds\u00a0<\/span><\/span><\/span><\/span><\/b><\/p>\n

      \u00a01)<\/span><\/span><\/span><\/b> Make a trench or circular hole next to the grounding electrode with a maximum distance of <\/span><\/span><\/span>10 cm<\/span><\/span><\/span><\/b><\/span> and fill the hole with one of the previously mentioned chemicals ( <\/span><\/span><\/span>MgSO4<\/span><\/span><\/span><\/b> or <\/span><\/span><\/span>CuSO4<\/span><\/span><\/span><\/b> ) up to <\/span><\/span><\/span>30 cm<\/span><\/span><\/span><\/b><\/span> from the grounding level, then the hole is covered with soil.<\/span><\/span><\/span><\/span><\/div>\n

      \u00a02)<\/span><\/span><\/span><\/span><\/b> Periodically provide the hole with a little water for good absorption of salts (chemicals).\u00a0<\/span><\/span><\/span><\/span><\/span><\/p>\n

      \n

      \"Soil<\/p>\n

      <\/div>\n

      \u00a0<\/span><\/p>\n<\/div>\n

      Soil chemical treatment is not a permanent method to improve the grounding resistance of an electrode as chemicals are likely to be washed away by precipitation and natural drainage through the soil and the replacement period for these chemicals varies depending on the amount of rainfall and the porosity of the soil.<\/span><\/span><\/span><\/span><\/span><\/div>\n
      It may take several years before another treatment or chemical replacement is needed.<\/span><\/span><\/span><\/span><\/span><\/div>\n

      One good advantage of chemical treatment is that it reduces the seasonal variation in resistance that results from wetting and drying of the soil.<\/span><\/span><\/span><\/span><\/span><\/p>\n

      \u00a02\u00a0 <\/span><\/span><\/span><\/span><\/b><\/span> bentonite<\/span><\/span><\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/div>\n

      Bentonite<\/span><\/span><\/span><\/span><\/b> is a yellowish-white sodium montmorillonite clay formed from altered volcanic ash.<\/span><\/span><\/span><\/span><\/span><\/p>\n

      It is a seasonal retaining clay used to reduce contact earthing resistance and increase the effective size of earthing electrodes as a backfill for earthing rods installed in buried holes or as a coating for earthing conductors buried horizontally in a trench.<\/span><\/span><\/span><\/span><\/p>\n

      \"Bayonet\"<\/p>\n

      <\/div>\n
      \n

      Advantages of bentonite as a backfill material<\/span><\/span><\/span><\/span><\/b><\/p>\n

      \u00a0<\/span>1\u00a0<\/span><\/span><\/span><\/b><\/span> \u00a0Bentonite is a super absorbent material in that when it comes in contact with water, it absorbs up to five times its own weight and expands up to thirteen times its original dry volume, increasing the walking area contact between the grounding electrode and the surrounding soil. <\/span>which improves the overall grounding resistance.\u00a0<\/span><\/span><\/span>
      <\/span><\/p>\n

      \u00a0<\/span>\u00a02\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite is strongly hygroscopic in water so it has a great ability to absorb water\u00a0<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a03\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite has the ability to absorb moisture from the surrounding soil and retain water or its moisture content for a long period of time at atmospheric pressure, and this will reduce grounding resistance.\u00a0<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a04\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite is a non-corrosive material even for a long period of time, so it protects the grounding electrode.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a05\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite is a stable material because it does not change its properties over time.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a06\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite is cost effective as we can obtain the required grounding resistance with a small amount when compared to other cement based solutions.<\/span><\/span><\/span><\/span>\u00a0<\/span>
      <\/span><\/p>\n

      \u00a0<\/span>\u00a07\u00a0<\/span><\/span><\/span><\/b><\/span> The resistivity of bentonite depends on its moisture content. Its resistivity varies from 3 ohms m in the wet condition and up to 18 ohms m in the dry condition.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a08\u00a0<\/span><\/span><\/span><\/b><\/span> Bentonite can be in the form of granules or powder, the granular form is preferred for filling trenches while the powder form is preferred for pouring into wells.<\/span><\/span><\/span><\/span>\u00a0<\/span>
      <\/span><\/p>\n

      \u00a0<\/span>\u00a09\u00a0<\/span><\/span><\/span><\/b><\/span> Due to the presence of impurities in the soil, the bentonite will retain the enclosure of the buried grounding rod or electrode and will not be washed away, thus we will not need to replace the bentonite\u00a0<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>Bentonite 10 should not be used<\/span><\/span><\/span><\/b><\/span> in very dry locations and free draining locations.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n<\/div>\n

      Bentonite composition<\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/p>\n

      Bentonite is suitable for use in wells and trenches<\/span><\/span><\/span><\/span><\/div>\n

      mixing bentonite<\/span><\/span><\/span><\/u><\/span><\/b>\u00a0<\/span><\/p>\n

      Bentonite expands at a rate that depends on the amount of water it is mixed with. <\/span><\/span><\/span>
      As a rule of thumb, assume an expansion ratio of 2:1 <\/span><\/span><\/span>

      \n1 x 25kg = 1 cu ft or 0.0283 cubic meters (dry) <\/span><\/span><\/span>
      1 x 25 kg bag = 2 ft\u00b3 or 0.0566 cubic meters (wet)<\/span><\/span><\/span><\/b>
      <\/span><\/div>\n

      \u00a0Case <\/span><\/span><\/span><\/span>in point<\/span><\/span><\/span><\/span><\/b><\/span>\u00a0<\/b>\u00a0<\/span><\/p>\n


      \nIf we have<\/span><\/span><\/span><\/span> 4 <\/span><\/span><\/span>earthing rods inserted into the wells (<\/span><\/span><\/span><\/span> 10 cm wide <\/span><\/span><\/span>,<\/span><\/span><\/span><\/span> 3 meters deep <\/span><\/span><\/span>), calculate the amount of bentonite required to fill these wells??<\/span><\/span><\/span><\/span><\/b>
      <\/span><\/p>\n


      \nWell volume =<\/span><\/span><\/span><\/b> 2 x (r\u00b2 x h) = 2 x (3.1416 x (0.1)\u00b2 x 3) <\/span><\/span><\/span>
      <\/span>
      \nnumber of bags<\/span><\/span><\/span><\/b> = \/0.0566 = bag<\/span><\/span><\/span><\/span><\/p>\n<\/div>\n

      \u00a0<\/span><\/div>\n
      Installation of bentonite in the well<\/span><\/span><\/span><\/b><\/span><\/div>\n

      \u00a01)<\/span><\/span><\/span><\/b> At the desired pole location, dig a hole 75-100 cm (3-4 inches) wide at a depth specified by the grounding system designer.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a02)<\/span><\/span><\/span><\/b> Insert the pole or rod vertically into the center of the well with the top of it at the right level for the wire connections.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a03)<\/span><\/span><\/span><\/b> Backfill the well with bentonite clay<\/span><\/span><\/span><\/span><\/div>\n

      \u00a0\u00a0<\/b>4)<\/span><\/span><\/span><\/b> Remove excess standing water from the trench<\/span><\/span><\/span><\/span><\/p>\n

      \u00a0<\/span><\/div>\n

      \"Installation<\/p>\n

      <\/div>\n
      \u00a0<\/span><\/div>\n
      Installation of bentonite in the trench<\/span><\/span><\/span><\/b><\/span><\/div>\n
      \n

      \u00a01)<\/span><\/span><\/span><\/b> At the desired rod location, dig a trench 200-300 mm (8-12 in) wide at a depth of 600 mm below the grounding level or depth specified by the grounding system designer.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a02)<\/span><\/span><\/span><\/b> Fill the bottom of the trench with a 25-50 cm (1-2 inch) thick layer of bentonite and place the ear bar or plate inside the bentonite layer making sure not to press it too much into the bentonite.<\/span><\/span><\/span><\/span><\/div>\n

      \u00a03)<\/span><\/span><\/span><\/b> Apply another layer of bentonite 25-50 cm (1-2 inch) thick and make sure that the grounding tape is completely covered.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a04)<\/span><\/span><\/span><\/b> Carefully backfill and compact the rest of the trench.<\/span><\/span><\/span><\/span><\/div>\n
      \u00a0<\/span><\/div>\n

      \"Installation<\/p>\n

      <\/div>\n

      \u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a03\u00a0 <\/span><\/span><\/span><\/b><\/span>Grounding Reinforcement Materials <\/span><\/span><\/span><\/b>(GEM)<\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/b><\/div>\n
      <\/div>\n
      \n

      \"Grounding<\/p>\n

      \u00a0Advantages of GEM as an infill material\u00a0<\/span><\/span><\/span><\/span><\/b><\/p>\n

       <\/p>\n

      \u00a0<\/span>\u00a01\u00a0<\/span><\/span><\/span><\/b><\/span> Ground Improvement Material (GEM) is a superconductive material that improves grounding efficiency especially in areas with poor conductivity and solves the most difficult grounding problems.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a02\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is a low resistivity, non-corrosive, carbon dust-based material that improves grounding effectiveness, regardless of soil conditions. <\/span><\/span><\/span>It is an ideal material to be used in areas with poor conductivity, such as sandy soils, rocky grounds, and mountain tops.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a03\u00a0<\/span><\/span><\/span><\/b><\/span> GEM contains Poltrand cement, which sets in 3 days and fully cures in 28 days, becoming a permanent, maintenance-free conductive concrete that will never leak or fade.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a04\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is the best material you can use to reduce grounding resistance.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a05\u00a0<\/span><\/span><\/span><\/b><\/span>\u00a0<\/span> GEM maintains permanently low grounding resistance and provides high conductivity for the life of the earthing system once in its specified configuration.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a0<\/span>\u00a06\u00a0<\/span><\/span><\/span><\/b><\/span> GEM does not negatively affect the soil because it does not contain any hazardous chemicals so it will not pollute the soil or ground water.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a07\u00a0<\/span><\/span><\/span><\/b><\/span> GEM does not depend on the constant presence of water to maintain conductivity.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a08\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is a permanent material that does not degrade, melt, or leak over time.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0\u00a09\u00a0<\/span><\/span><\/span><\/b><\/span><\/span> GEM does not require periodic charge handling nor replacement.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a010\u00a0<\/span><\/span><\/span><\/b><\/span> GEM works in all soil conditions regardless of the presence of water.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a011\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is easy to install as it does not require any special tools and requires only one person to install and also requires no maintenance.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a012 GEM can be easily installed\u00a0<\/span><\/span><\/span><\/b><\/span> in dry or slurry form.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a013\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is not affected by freezing because freezing only increases resistance by 10-15%.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a014\u00a0<\/span><\/span><\/span><\/b><\/span> GEM is non-corrosive because it contains a corrosion inhibitor that forms a thin film on the surface of the rod creating a barrier against corrosion.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a015\u00a0<\/span><\/span><\/span><\/b><\/span> GEM reduces theft and vandalism as grounding rods and conductors are difficult to remove when set in concrete.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      \u00a0<\/span>\u00a016\u00a0<\/span><\/span><\/span><\/b><\/span> GEM has a very low resistivity (less than 0.02 Ohm m) which is only 1% of the resistivity of bentonite clay.<\/span><\/span><\/span><\/span>\u00a0<\/span><\/p>\n

      Applications<\/span><\/span><\/span><\/b><\/span><\/p>\n

      \u00a0<\/span>\u00a0\u00a0<\/span>\u00a0<\/span>Grounding improver is the ideal material to be used in areas with poor conductivity, such as sandy soils, rocky grounds, and mountain peaks.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a0<\/span>\u00a0\u00a0<\/b><\/span>\u00a0<\/span>GEM is ideal for use in situations where it is difficult to drive grounding electrodes into grounding or where grounding space is limited making proper grounding difficult using conventional methods.<\/span><\/span><\/span><\/span><\/div>\n<\/div>\n<\/div>\n
      \n

      GEM installation<\/span><\/span><\/span><\/b><\/span>\u00a0<\/span><\/p>\n

      Bentonite is suitable for use in wells and trenches<\/span><\/span><\/span><\/span><\/div>\n
      \u00a0<\/span><\/div>\n
      Installing grounding reinforcement materials in the trench<\/span><\/span><\/span><\/b><\/div>\n
      1) At the desired rod location, dig a trench 10 cm (4 in) wide at a depth of 30 cm below the grounding level or depth specified by the grounding system designer.<\/span><\/span><\/span><\/span><\/div>\n

      \u00a02)<\/span><\/span><\/span><\/b> Mix the grounding reinforcement materials into a slurry using a cement mixer or mixing in a mixing bin or bucket. <\/span>Use 1.5 to 2 gallons (5.7 to 7.6 liters) of clean water for each bag of grounding reinforcement. <\/span><\/span><\/span>
      Do not mix with GEM salt water.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a03)<\/span><\/span><\/span><\/b> Cover the bottom of the trench with a layer of 2 cm (5 inches) thick.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a04)<\/span><\/span><\/span><\/b> Wait for the grounding reinforcement material to harden about 15 to 20 minutes and then place the grounding conductor over the jewel.<\/span><\/span><\/span><\/span><\/div>\n

      \u00a05)<\/span><\/span><\/span><\/b> Apply another layer of grounding reinforcement material over the conductor and be sure to cover the entire conductor – about 2 inches (5 cm) deep.<\/span><\/span><\/span><\/span><\/p>\n

      \u00a06)<\/span><\/span><\/span><\/b> Wait 30 minutes to an hour and then fill the trench with backfill soil, making sure not to expose the conductor.<\/span><\/span><\/span><\/span><\/div>\n

      Notes:-<\/span><\/span><\/span><\/span><\/span>
      <\/span><\/p>\n