Ground

[henry1223]

We recently did a wharehouse job that is devided into three seperate units, each one of them has it's own 200amp service(each one having it's ground rod). We called yesterday for a service inspection and failed. The reason being the inspecter said all the grounds need to be grounded together.(basically loop all the rods together).For the sake of not sounding stupid can anybody give me an eplination of why?


Thank You!

 

[iwire]

can anybody give me an eplination of why?

Sure...becuase the code requires it.

250.58 Common Grounding Electrode.
Where an ac system is connected to a grounding electrode in or at a building as specified in 250.24 and 250.32, the same electrode shall be used to ground conductor enclosures and equipment in or on that building.

Where separate services supply a building and are required to be connected to a grounding electrode, the same grounding electrode shall be used.

Two or more grounding electrodes that are effectively bonded together shall be considered as a single grounding electrode system in this sense.

I suspect the reason for this is to ensure that all the services grounded conductors remain at the same potential during normal and fault conditions.

Now you say this is a warehouse, is it made out of steel?

If the structure is made of steel you must bond each service to the steel.

Once each service is bonded to the steel they are now all bonded together.