Size of neutral NOT terminated in disconnect

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sfav8r

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Using the tap rules (10') we are feeding a disconnect with 250mcm. The disconnect is fused with 30a fuses and there will be #10 on the load side feeding the load. The only reason for the 250mcm is due to the the fact that this is a tap. My question is, the only use of the neutral is for the load we are feeding. Since the neutral passes through the disconnect and feeds the 30a load, can it just be a #10? Is there a code section I can reference for this?

Thanks, and Happy Thanks Giving to everyone.
 
sfav8r said:
Using the tap rules (10') we are feeding a disconnect with 250mcm. The disconnect is fused with 30a fuses and there will be #10 on the load side feeding the load. The only reason for the 250mcm is due to the the fact that this is a tap. My question is, the only use of the neutral is for the load we are feeding. Since the neutral passes through the disconnect and feeds the 30a load, can it just be a #10? Is there a code section I can reference for this?

Thanks, and Happy Thanks Giving to everyone.
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How are you getting 250mcm into a disconnect that holds 30 amp fuses? Fuse reducers?

Yes, the neutral can be #10, but if that is true why do you need anything bigger than 10s for your taps feeding your disconnect?
 
So many questions.

First off what size is the overcurrent protection protecting the feeder you are tapping?

Why 250 to a 30 amp disconnect?

What is the ampacity and load you are supplying?

What size equipment grounding conductor will you run between the tap and the disconnect?
 
Thanks for the replies.

Yes, we are able to feed the 30a disco with 250s because it is a 600v 100a disco with 250 lugs and fuse reducers. The reason for the 250s is that we are tapping off the main which is (I think) 2500a.

Ptonsparkey you mention it is ok to run just the #10, do you have a code section I can review?

Thank you
 
The tap conductors are feeder conductors and 215.2(A)(2) specifies the minimum size of the grounded conductor for a feeder.
 
sfav8r said:
Thanks for the replies.

Yes, we are able to feed the 30a disco with 250s because it is a 600v 100a disco with 250 lugs and fuse reducers. The reason for the 250s is that we are tapping off the main which is (I think) 2500a.

Ptonsparkey you mention it is ok to run just the #10, do you have a code section I can review?

Thank you
Click to expand...

How did you tap a 2500 amp feeder? That gets tricky with parallel sets.

Also the EGC size from tap to disconnect must be sized per the 2500 amp OCPD.
 
don_resqcapt19 said:
The tap conductors are feeder conductors and 215.2(A)(2) specifies the minimum size of the grounded conductor for a feeder.
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iwire said:
How did you tap a 2500 amp feeder? That gets tricky with parallel sets.

Also the EGC size from tap to disconnect must be sized per the 2500 amp OCPD.
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...but not required to be larger than the tap conductors [250.122(G)]. So 350kcmil* Cu to tap point, #10 after tap.

*Feeder EGC may be bus within appropriately rated gear. In this case, the EGC size prior to tap point is irrelevant.
 
sfav8r said:
Thanks for the replies.

Yes, we are able to feed the 30a disco with 250s because it is a 600v 100a disco with 250 lugs and fuse reducers. The reason for the 250s is that we are tapping off the main which is (I think) 2500a.

Ptonsparkey you mention it is ok to run just the #10, do you have a code section I can review?

Thank you
Click to expand...
What size lugs came with your Disc?
Look at 240.21 all the way though and including 240.23.
 
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