sub panel feed through panel conductors

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sparky23

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question and i have a 200A feedthrough panel feeding a 125 sub panel, so bottom lugs only need 1/0 - where is this in nec? i dont want to pull 3/0 ...

thabks in advance
 
If you want to feed a subpanel from the feedthru lugs you can use a reduced size conductor if you follow the 240.21 tap rules.
 
I agree with Gus, since you have feed-through conductors that are rated for less than 200 amps you need to apply a tap rule. Which means that you need an OCPD ahead of the 125 amp panel. If you use 200 amp feed-through conductors then a MLO panel will be fine.
 
i have a 100A cb but no space on bar between lugs..... i am looking for some in between switch from lug to 1/0 conductors, this is the question about products....
 
How far apart are the two panels? If it's 25' or less you can use the 25' rap rule and just put a main CB in the second panel.
 
conductors in pvc are 1/0
i was sure that i an not connect 1/0 to bottom feed thru lugs on 200 A panel
thats how this started - someone pulled 1/0 from 125A sub panel to a 200A feed thru - and it looked not right to me.
they asked if they could use cb 100A i said yes - but the 1/0 are too large to fit Cb and there was no space for 2pole CB
 
Agreed: You do not need the separate 125a fused disco if the conductors land on a disconnect in the sub-panel.

In other words, tap rules allow the breaker at the load end of the 1-0 conductors, just like the main in your service.
 
sparky23 said:
conductors in pvc are 1/0
i was sure that i an not connect 1/0 to bottom feed thru lugs on 200 A panel
thats how this started - someone pulled 1/0 from 125A sub panel to a 200A feed thru - and it looked not right to me.
they asked if they could use cb 100A i said yes - but the 1/0 are too large to fit Cb and there was no space for 2pole CB
Click to expand...

I'm surprised that a #1/0 won't fit in a 100 amp circuit breaker, even Square D Homeline accepts up to #2/0. Your sketch didn't include conductor lengths but I'm assuming that it's more than 25' from the feed-through lugs to the panel so you'll need the fused disconnect or a circuit breaker as shown in your drawing.
 
yes soory for no lengths - i did not strip wire for them - it just looked narrow - the sub-panel is about 50 feet - maybe 60 feet from 200s feed thru - would it be great if they just made space available in 200A - panel -
 
If the tap conductors happen to be outdoors they can be unlimited length.

This generally useful for supplying a separate building.
 
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