6 Factors Influencing Requirements for a Good Grounding System

6 Factors Influencing Requirements for a Good Grounding System

Six Requirements To Consider

In an industrial plant or other facility that requires a grounding system, one or more of the following must be carefully considered (refer to Figure 1 below):

Typical conditions to be considered in a plant ground system

Figure 1 – Typical conditions to be considered in a plant ground system

1. Limiting Voltage

Limiting to definite values the voltage to earth of the entire electrical system. Use of a suitable grounding system can do this by maintaining some point in the circuit at earth potential.

Such a grounding system provides these advantages:

  • Limits voltage to which the system-to-ground insulation is subjected, thereby more definitely fixing the insulation rating.
  • Limits the system-to-ground or system-to-frame voltage to values safe for personnel.
  • Provides a relatively stable system with a minimum of transient overvoltages.
  • Permits any system fault to ground to be quickly isolated.

2. Grounding of Metallic Parts

Grounding of cable trays

Grounding of cable trays


Proper grounding of metallic enclosures and support structures that are part of the electrical system and may be contacted by personnel. Also to be included are portable electrically operated devices.

Consider that only a small amount of electric current – as little as 0.1 A for one second – can be fatal! An even smaller amount can cause you to lose muscular control. These low currents can occur in your body at voltages as low as 100 V, if your skin is moist.


3. Static Electricity

Protection against static electricity from friction. Along with this are the attendant hazards of shock, fire and explosion.

Moving objects that may be inherent insulators – such as paper, textiles, conveyor belts or power belts and rubberized fabrics – can develop surprisingly high charges unless properly grounded.

4. Direct Lightning Strokes

Lightning strike on lightning rod

Lightning strike on lightning rod


Protection against direct lightning strokes. Elevated structures, such as stacks, the building proper, and water tanks may require lightning rods connected into the grounding system.


5. Induced Lightning Voltages

Illustration of direct and indirect lightning strokes

Illustration of direct and indirect lightning strokes


Protection against induced lightning voltages. This is particularly a factor if aerial power distribution and communications circuits are involved.

Lightning arresters may be required in strategic locations throughout the plant.

6. Low-resistance Ground Connections

Providing good grounds for electric process control and communication circuits.

With the increased use of industrial control instruments, computers, and communications equipment, accessibility of low-resistance ground connections in many plant locations – in office and production areas – must be considered.

Reference: Getting down to Earth – A practical guide to earth resistance testing – MEGGER


About Author //

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Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears. Professional in AutoCAD programming and web-design. Present on



2 Comments


  1. UDAYAN MASHRUWALA
    Jun 12, 2014

    Very good I loved this


  2. UDAYAN MASHRUWALA
    Jun 12, 2014

    Love this site as it is very use full for electrical engineer

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