SSBJ, Neutral, or Both?

Q

quantum

Senior Member
Location
LA
I'm planning an installation similar to the image attached. A switch board will be used instead of a panelboard. Primary is supplied by utility, but the transformer is customer owned. Multiple parallel sets will be installed on PVC from the transformer secondary (480/277 wye) to the switch board (service entrance rated) with phase conductors and a neutral on each conduit. I don't see any reason to install SSBJs between the transformer and switch board other than it's usually said SSBJs are always required on customer owned transformers. Am I overthinking this?

1000006672.jpg
 
See 250.30(A)(2). ".... a supply-side bonding jumper shall be installed with the circuit conductors from the source enclosure to the first disconnecting means enclosure. ..."

In the drawing the SSBJ is the fault clearing path for a secondary winding or secondary conductor fault at the transformer enclosure.
 
In the drawing, 4 wires are shown, 3 phase conductors and 1 neutral. Based on 250.30(A)(2) implies that a 5th wire to be installed with the circuit conductors between the transformer and the switch board. Which is what I would install on a feeder supplied, customer owned transformer in the field. This being a service transformer has me second guessing since I've seen this diagram in the Stallcup's manual.
 
With PVC conduits and an outdoor transformer you can likely omit the SSBJ per the exceptions in 250/30(A)(1) and (A)(2)
 
augie47 said:
With PVC conduits and an outdoor transformer you can likely omit the SSBJ per the exceptions in 250/30(A)(1) and (A)(2)
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That require as system bonding jumper at both the transformer and the first disconnect, and the drawing does show that. I missed that.
 
augie47 said:
With PVC conduits and an outdoor transformer you can likely omit the SSBJ per the exceptions in 250/30(A)(1) and (A)(2)
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250.30(A)(2) exception refers back to 250.30(A)(1) Exception 2, which states ".... supplied by a feeder from an outdoor separately derived system..." Since this is a service, I can't apply that one. Either the diagram in the Stallcup's guide is wrong or I'm misinterpreting something.
 
quantum said:
250.30(A)(2) exception refers back to 250.30(A)(1) Exception 2, which states ".... supplied by a feeder from an outdoor separately derived system..." Since this is a service, I can't apply that one. Either the diagram in the Stallcup's guide is wrong or I'm misinterpreting something.
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Where is the service point for this service? Remember that the location of the service point is wherever the utility says it is. I have never seen a service point that is on the secondary side of a customer owned transformer.
 
don_resqcapt19 said:
Where is the service point for this service? Remember that the location of the service point is wherever the utility says it is. I have never seen a service point that is on the secondary side of a customer owned transformer.
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