Neutral bring to disconnect

[jaggedben]

To summarize, my understanding is that the code allows either
1) SBJ at XF and no SBJ at both disconnects, with SSBJs run to both disconnects
2) SBJs at all three locations, with neutral (and no SSBJ) run to both diaconnects..

There are two problems with OP's description of situation:
First, no SBJ at XF, which is required.
Second, SWB was done according to (2) above, and fire pump was done according to (1), which results in objectionable neutral current on the fire pump SSBJ if both disconnects are grounded to the building GES as required.

The fire pump and SWB can be done either way but must both be done the same way to avoid the objectionable current.

YES fire pump controller 3 phase, 3 wire fed by the transformer secondary feeder with EGC and no neutral.

If the description is of what is already installed, I hope that 'EGC' is large enough to be a black wire that can be retaped white and satisfy table 250.102(C)(1).

 

[wwhitney]

To summarize, my understanding is that the code allows either
1) SBJ at XF and no SBJ at both disconnects, with SSBJs run to both disconnects
2) SBJs at all three locations, with neutral (and no SSBJ) run to both disconnects..

Upon reflection, I don't believe that (2) is an option when you have more than one disconnect at the building from a single outdoor SDS. Configuration (2) relies on 250.30(A)(1) Exception 2, which requires that the extra SBJ at the first means of disconnect not "establish a parallel path for the grounded conductor."

But if you have multiple disconnects at the building, the building GEC/GES connection at each disconnect will interconnect the EGC systems at each disconnect, as well as the grounded conductors at any disconnects with SBJs. So if you have at least 2 disconnects with SBJs, each SBJ is establishing a parallel path for the associated grounded conductor, via GES/GEC to one of the other SBJs to its associated grounded conductor.

So I think that 250.30(A)(1) Exception 2 can only be used when an outdoor SDS supplies only a single feeder to the building. Which means that (1) above is the only compliant option for the installation in the OP.

Cheers, Wayne

 

[tortuga]

.I don't, we don't use them

I think you do describe their meaning quite well;

Our systems are TN-C from the utility to the service equipment. A main bonding jumper is installed in the service equipment and the system is TN-S from that point on.

TN-C has never been permitted downstream of the service equipment by the NEC.

https://forums.mikeholt.com/threads/grounding-on-legacy-system.2589480/post-3025020

 

[don_resqcapt19]

I think you do describe their meaning quite well;


https://forums.mikeholt.com/threads/grounding-on-legacy-system.2589480/post-3025020

only after looking it up to answer a question.

I see no need for any user of the NEC to have any knowledge of that terminology unless it starts being used in the code.