jmercado
Member
- Location
- new york, NY, USA
If a transformer pad, external to the main building, has its own grounding grid (ground rods + 4/0 welded loop), is it code compliant? Does it need to tie into the main building electrode?
External Transformer to a main building
- Thread starter jmercado
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IMO, it is compliant as is.
Is this a service transformer or an SDS (Separately Derived System)? If an SDS, you will get opinions on both sides of the fence, especially if it is anywhere close to the building.
- Location
- Illinois
- Occupation
- retired electrician
Does the transformer supply the building? If so there will be a connection via the required supply side bonding jumper. It may be indirect at the SSBJ may not be directly connected to the GECs at each end.
jmercado
Member
- Location
- new york, NY, USA
The transformer does not provide the buildings main power.
jmercado
Member
- Location
- new york, NY, USA
My situation is that we followed the conformance set of drawings. The engineer at a later date requested to run a conduit and cable to tie the transformer ground.
I am trying to determine if the original grounding grid for the external transformer, that was on the drawings, was efficient and code compliant. I believe that the additional grounding electrode to the building was above and beyond the code, which I would like the general contractor to pay for.
I am trying to determine if the original grounding grid for the external transformer, that was on the drawings, was efficient and code compliant. I believe that the additional grounding electrode to the building was above and beyond the code, which I would like the general contractor to pay for.
If I understand correctly. this is a non-utility, non-service transformer and simply a Separately Derived System with primary and secondary connected to the building.
The NEC has played with this somewhat changing terminologies between the '08 Code (which your profile lists as your Code).
As I read it, your equipment bonding jumper ('08 term) would essentially connect your transformer to the building grounding system and IMO there would be no need for a GEC to the building,.
The NEC has played with this somewhat changing terminologies between the '08 Code (which your profile lists as your Code).
As I read it, your equipment bonding jumper ('08 term) would essentially connect your transformer to the building grounding system and IMO there would be no need for a GEC to the building,.
Determine as you will, but I see this as a gray area, subject to the interpretation powers that be. For example, even though outside the building, some will say compliance with 250.30(A)(4) is still required. There is nothing in the Code that says the GEC is not required if the transformer is outside the building. The other side of the fence is lined with people that say the transformer is a separate structure, so 250.30(A)(4) Exception No. 1 applies.
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