Pole-mount transformer SDS - Non-utility

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nhee2

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I have a customer owned pole-mount transformer bank, (480/277, 3 ph) from which we are running an UG feeder approx. 200' to a new structure. I want to be sure I have my grounding correct -

- 4-wire (A,B,C,N) from xfmrs to fused disconnect on pole. N-G bond at fused disconnect on pole, sized per 250.30A/250.102(C). Ground electrode at pole.
- 4-wire + EGC feeder from pole disconnect to disconnect at new structure. EGC sized per 250.32 (B)(1).
- Grounding electrode at new structure, per 250.32(A). No N-G bond at new structure.

What I am not sure of is if I need a SSBJ between the transformer bank and first disconnect.
 
Read the exception to 250.32(A)(2).
It appears to me to depend on how your system bonding conductors are connected.

Curious. Why the disconnect on the pole and not just a secondary run to the structure??
 
augie47 said:
Curious. Why the disconnect on the pole and not just a secondary run to the structure??
Click to expand...
Good question, I was thinking I needed secondary conductor protection but see 240.21(C)(4) probably covers me so I could eliminate that switch.

Thanks.
 
EGCs do not exist on the line side of the first overcurrent protective device for the SDS.

A supply side bonding jumper is required. The installation on a pole is not common, but it really doesn't change anything.

If the System Bonding Jumper is at the transformer, a Supply Side Supply Bonding Jumper will be connected at the System Bonding Jumper and run to the EGC bar at the fist disconnect.

If the SBJ is at the first OCPD, the SSBJ will run from that point and bond to the metal transformer enclosures.
 
don_resqcapt19 said:
EGCs do not exist on the line side of the first overcurrent protective device for the SDS.

A supply side bonding jumper is required. The installation on a pole is not common, but it really doesn't change anything.

If the System Bonding Jumper is at the transformer, a Supply Side Supply Bonding Jumper will be connected at the System Bonding Jumper and run to the EGC bar at the fist disconnect.

If the SBJ is at the first OCPD, the SSBJ will run from that point and bond to the metal transformer enclosures.
Click to expand...
Just want to mention if this is outdoors, one would likely use the exception that allows bonding at both ends and skipping the SSBJ. don't have my code but handy but I think this is what Augie mentioned previously .
 
Thanks for the replies.

electrofelon said:
Just want to mention if this is outdoors, one would likely use the exception that allows bonding at both ends and skipping the SSBJ. don't have my code but handy but I think this is what Augie mentioned previously .
Click to expand...

Yes, I think that this exception allows elimination of any SSBJ.
 
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