Equipment Grounding Conductor - Required or Not?

Not sure about what you mean. All the equipments are already grounded. If your ground is of sufficient capacity, you do not again connect the ground (or earth wires) above ground why should you? We have a large factory where each individual machine has its own earth pit and they are grounded there - why carry another extra cable and connect each earth pits ?

In which jurisdiction will this equipment be installed? Read the codes for your area!!

Also make sure you understand the differences between grounding and bonding and the requirements for each. It can be important; particularly under ground fault and surge conditions; such as lightning discharge.

Quote by SB "

"Not sure about what you mean. All the equipments are already grounded. If your ground is of sufficient capacity, you do not again connect the ground (or earth wires) above ground why should you? We have a large factory where each individual machine has its own earth pit and they are grounded there - why carry another extra cable and connect each earth pits ?"

SB

would you describe what you mean by "earth pit". In the US a piece of equipment is grounded by an equipment grounding conductor(EGC) that is electrically connected to the main switch and electrode grounding conductor. Connecting equipment to earth is not allowed as a replacement to the EGC. A phase to ground fault would not trip a breaker if the earth was the only return path for the fault current.

Mr. SB I appreciated your answer In our case all equipments are inside the building and earth pits are located outside the building but all earth pits are connected with 120mm2 electrode grounding conductor pvc sheathed (5*5 meter) mesh below grade level and near each equipments grounding riser tapped through cadweld joints.In case of phase to ground fault the current will not flow through earth, it will flow through electrode grounding conductor,Each equipments ground are interconnected through electrode grounding conductor. Is it required the equipment grounding conductor for above case.

Have you taken a meter and checked to see what shows on the wires between the neutral and the ground? If the overall system, circuit is well grounded it ought not be necessary to ground individual components on that system. However when running lights I have had cases in heavy rain, when the ground for the circuit system was not good enough, and we all got bites. It is not at all unusual for grounding of a system to be inadequate. I suggest you get an electrician to meter all phases and see what is running in the wires and where it is going. I also suggest you make sure all phases are as balanced as practical. Regardless, grounding is good.