tap rule for sub-panel

[MasterMike]

First the tap was made with 4/0 AMG Copper Wire.
A copper to copper tap, 4/0 awg Copper to 500 Kcmil Copper

Secondly I still find no reference to a panelboard where a panelboard can not be used as a tap means. The Tape rules of 240.21 B1 have been met in this situation (This is only the way I interpret it)

I still can't find any section that would deny this installation, this is where the question lies.

 

[MasterMike]

The TAP is not the problem.....The problem is the 4/0 AL used to tap to the main lugs....in the 10' tap rule the wire must be sized to meet the size or rating of the device the taps are going to...in this case 200A panel so the TAPS would need to be 3/0 CU or 250 KCMIL

Again the wire that is the TAP must be able to handle the ampacity of the rating of the device...

No AL was Used

 

[radiopet]

Mike,

I do not believe their is anything that says you can't tap at the terminal if the terminal is rated as such. As long as the TAP conductors are sized correctly and they are sized to handle the device fed from the taps.

I don't think providing a reference will change the mind of the local AHJ in this case...but I could be wrong.........Or I have been wrong before no doubt.

Thanks for the clarrification on the 4/0 being CU versus AL.....that would certainly be a problem.....if it was AL....guess I assumed...sorry.

 

[MasterMike]

Still Interesting

Still Interesting

I have to say it has been awhile since I have run across something that has take awhile to look up and found no answer. Not sure how to proceed except revisit the AHJ.. They had a problem finding something in the code to substantiate their statement.

 

[Dexie123]

Hello all. 1st post ever! Chronic lurker.

Few questions Bob as I'm very dense on this subject.

Using the tap rules you could install a sub panel with a main breaker with any rating under 100 amps, but the sub panel would need to be close to the main panel.

Say 6 awg copper feeding a 60 amp main breaker sub panel.

1st we are saying that the Main Panel just has main lugs or is being backfeed through a breaker and we are attaching on the load side of that breaker? If we're tapping off the main lugs then you can terminate into a subpanel that has an OCPD to a 60amp subpanel OCPD?
If this is so what about the 10% rule for within 10 feet and 1/3 rule for 25 feet? Or does that only count from tapping off a branch circuit?

You can use the unused lugs t feed a sub panel.

Or you could install a 100 amp or larger main lug only sub panel feed it with 100 amp minimum rated conductors as far away from the main panel as you want.

I'm assuming that this is the case if you use a subpanel breaker in the main panel?

Thanks!