Xfmr grounding

rojay

Member
Location
Chicago,IL USA
If a water pipe is used as the grounding electrode to ground a transformer secondary, is the water pipe electrode required to be supplemented? I don’t see why this wouldn’t still be the case, but I can’t ever recall seeing supplemental rods- rods yes, when water or steel wasn’t available, but never both.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
250.30(A)(4) requires you to use the building grounding electrode system, so the supplement to the water pipe should already be taken care of.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If the water pipe does not meet the requirements of 250.68(C)(1) can it be used as a grounding electrode for a SDS if the connection is not with in the 1st 5 ft ??
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
If the water pipe does not meet the requirements of 250.68(C)(1) can it be used as a grounding electrode for a SDS if the connection is not with in the 1st 5 ft ??
It can't be used as the grounding electrode unless the connection is made within the first 5' of the water pipe. However the SDS is still required to be bonded to the water pipe in the area of the SDS by 250.102(D)(1).

Should be 250.104(D)(1)
 
Last edited:

Dell3c

Senior Member
Location
WA
Occupation
Electrician
It can't be used as the grounding electrode unless the connection is made within the first 5' of the water pipe. However the SDS is still required to be bonded to the water pipe in the area of the SDS by 250.102(D)(1).
I'm coming up little empty on 250.102(D)(1).. Can't seem to locate inside my NFPA 2020 edition..
 

augie47

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Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
It can't be used as the grounding electrode unless the connection is made within the first 5' of the water pipe. However the SDS is still required to be bonded to the water pipe in the area of the SDS by 250.102(D)(1).
IF it met all the requirements of the exception in 250.148(C), would it not be permissible to connect beyond the 5 ft.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
IF it met all the requirements of the exception in 250.148(C), would it not be permissible to connect beyond the 5 ft.
That is not for GECs. It would have to meet the exception to 250.68(C)(1) to be used as the connection point beyond 5' from the water pipe's point of entrance into the building.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
250.30(A)(4) requires you to use the building grounding electrode system, so the supplement to the water pipe should already be taken care of.
If you use the original existing building GES, and the customer transformer is remote as in several hundred feet away from the service equipment and GES.

Must you run a GEC all the way to the transformer, or could you create a new GES specifically for the transformer and it be bonded to the original building GES via the EGC?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
If you use the original existing building GES, and the customer transformer is remote as in several hundred feet away from the service equipment and GES.

Must you run a GEC all the way to the transformer, or could you create a new GES specifically for the transformer and it be bonded to the original building GES via the EGC?
The code clearly requires a connection to the building grounding electrode system. If the building is structural steel, you could connect to the steel locally, otherwise you need a lot of wire.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
250.68(C) Exception ?.. if under conditions of maintenance & supervision?
Only your AHJ knows what that means. Some say it requires a qualified electrical person at all times, and others say it just means that only qualified electricians service the electrical system.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
The code clearly requires a connection to the building grounding electrode system. If the building is structural steel, you could connect to the steel locally, otherwise you need a lot of wire.
7F13F689-400C-4EEF-A6A0-1C65A29A66C3.jpeg This image pertains to the SBJ, but disregarding that. Is the GES in this setup correct? Being that it has no bonding jumper from building grounding electrode system to transformer grounding electrode system.
 

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
View attachment 2556845 This image pertains to the SBJ, but disregarding that. Is the GES in this setup correct? Being that it has no bonding jumper from building grounding electrode system to transformer grounding electrode system.
That appears to be a transformer that is not in the same building as the feeder to the transformer and in that type of installation, it can have its own grounding electrode system.
 

rojay

Member
Location
Chicago,IL USA
Don,
In the case that the water pipe is not suitable as a grounding electrode, and the only grounding electrode system being used for the building service consists of 2 ground rods, are two more rods required locally for the SDS w/ bonding back to the service rods?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Don,
In the case that the water pipe is not suitable as a grounding electrode, and the only grounding electrode system being used for the building service consists of 2 ground rods, are two more rods required locally for the SDS w/ bonding back to the service rods?
The way I read the code rules you have to use the building grounding electrode system where the SDS is in the building. There is no requirement to add additional electrodes for the SDS.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
Don,
In the case that the water pipe is not suitable as a grounding electrode, and the only grounding electrode system being used for the building service consists of 2 ground rods, are two more rods required locally for the SDS w/ bonding back to the service rods?
Is your transformer in the same building as your GES?
 
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