Is a ground rod needed in this scenario?

Tainted

Tainted

Senior Member
Location
New York
Occupation
Engineer (PE)
I asked an electrician to install a ground bus and tie it to grounding electrodes in the building.

He connected the ground bus to the water main and building steel. He didn't connect it to a ground rod because there is no ground rod in the building.

In this scenario, is a ground rod required? If yes where does it say that? I could have sworn I saw it somewhere...
 
wwhitney said:
See 250.53, in particular (D)(2) and (A)(2).

Cheers, Wayne
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(A)(2) does not exist in NYC electrical code because they still use 2008 version sooo...

Not sure if I'm reading it correctly but it seems like ground rod might not be required? A water main pipe is supplemented with a building steel? what is a plate electrode?
 
In NYC they do not require a ground rod if I have at least 10ft of sufficient building steel in direct contact with earth or encased in concrete that is in direct contact with dirt 250.52(A)(2).
But if for whatever reason a groundrod is installed you typically need to supplement it with another 250.56
 
Building steel does not supplement the GEC or ground rods it is just bonded to it. Every building needs a GEC. It is supposed to be connected to a metal water pipe if the pipe is at least 10' long. In addition to that you must have (1) ground rod if it is tested to be 25 ohms or less to ground. If it exceeds that (2) ground rods 6' apart are required.

If you pour a concrete incased electrode when the building is built you can eliminate the ground rods.

At least that is my understanding.
 
Tainted said:
What is a CEE

Gene6 brought up a good point about the 10 ft rule. I do not know if the structure is buried 10 feet.
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CEE= Concrete Encased Electrode. 20’ (min) of 1/2” rebar or #4 solid copper wire, in the footing.

They are required now in the last couple code cycles for new construction.

There are some exceptions, like a slab on grade building which is required to have 10 mil poly per Building Code, which negates the CEE.

In that case, 2 ground rods are used.

I don’t know anyone who does earth ground resistance testing to save a ground rod. The equipment for that test is very expensive. Ground rods are cheap.
 
250.52 list the electrodes suitable for grounding.
Some of those, such as building steel in contact with the earth vertically for 10ft or more, or concrete encased electrode or a ground ring are suitable as the sole electrode,. A metal underground water pipe in contact with the earth is an acceptable electrode but it must be supplemented by another acceptable electrode. A ground rod can be an acceptable electrode but unless the resistance of 25 ohms or less it must be supplemented.

Some power companies require a ground rod even when the NEC does not.

In your scenario a ground rod would not be needed IF the building steel qualified as an "In-ground support structure" (or if the steel was connected to a CEE)
 
If you drive a ground rod you might poke thru a into a subway. :D
There used to be a joke that all grounds in NYC are really tied together and end up in the M42 subbasement under grand central.
 
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