XFMR grounding

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Brandon Loyd

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Do you need an equipment grounding conductor pulled in with the primary of a xfmr or does the conduit count as the EGC? Do the primary or secondary conduits need to have ground bushings installed at the xmfr?
 
Egc

Egc

250.134 sends you to 250.118 which lets you use RMC, IMC, flex and regular wire (equipment grounding conductor) for bonding/grounding equipment.

Most gov't, commercial and industrial organizations require the equipment grounding conductor these days.
 
ericsherman37 said:
The primary side needs an equipment ground which can be any of the suitable methods (I always pull a conductor EGC regardless of my wiring/raceway method).

The secondary is usually a separately derived system and is bonded as such (main bonding jumper and so forth).

Here's an old thread I found with a good picture on it:

http://forums.mikeholt.com/showthread.php?t=84108
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When I say EGC, I mean an actual wire conductor. I thought it was REQUIRED to have one to have one installed in the primary conduit and the secondary conduit. And that the secondary conduit was REQUIRED to have a ground bushing installed. It sounds like you are saying that an actual wire is not REQUIRED on either. Is that correct? The drawing doesn't show wire in conduits.
 
Brandon Loyd said:
When I say EGC, I mean an actual wire conductor. I thought it was REQUIRED to have one to have one installed in the primary conduit and the secondary conduit. And that the secondary conduit was REQUIRED to have a ground bushing installed. It sounds like you are saying that an actual wire is not REQUIRED on either. Is that correct? The drawing doesn't show wire in conduits.
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billyzee said:
250.134 sends you to 250.118 which lets you use RMC, IMC, flex and regular wire (equipment grounding conductor) for bonding/grounding equipment.

Most gov't, commercial and industrial organizations require the equipment grounding conductor these days.
Click to expand...

If it's in your specs or prints to have a wire EGC then you probably should include it :D The NEC is fine with a wire or some metallic raceway EGCs.

On the secondary side, you can put your main bonding jumper in the transformer can or at the first disconnect like in the picture. Wherever that happens is where your EGC system starts. You still have to bond the transformer can to the rest of the secondary-supplied equipment. I think it'd be easier just to put the main bonding jumper in the transformer and land the GEC there and bond the can all in the same place, and then run an EGC out with the rest of the conductors.
 
Brandon Loyd said:
When I say EGC, I mean an actual wire conductor. I thought it was REQUIRED to have one to have one installed in the primary conduit and the secondary conduit. And that the secondary conduit was REQUIRED to have a ground bushing installed. It sounds like you are saying that an actual wire is not REQUIRED on either. Is that correct? The drawing doesn't show wire in conduits.
Click to expand...


If you have FMC on the primary chances are that you'll need an EGC since the FMC might not qualify as one. Bonding bushings would only be required where concentric or eccentric KO's were present on the raceway that contains conductors over 250 volts. IMO a conductor type EGC is required on the secondary.
 
infinity said:
If you have FMC on the primary chances are that you'll need an EGC since the FMC might not qualify as one. Bonding bushings would only be required where concentric or eccentric KO's were present on the raceway that contains conductors over 250 volts. IMO a conductor type EGC is required on the secondary.
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I dont understand the IMO reference. Can you please elaberate.
 
Brandon Loyd said:
I don't understand the IMO reference. Can you please elaborate.
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Since the equipment bonding jumper is on the secondary side of the transformer it would fall under 250.66 based on the size of the secondary conductors. The gray area is whether or not the EBJ is required to be a wire type conductor or can it be a metallic raceway.
 
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