Need some help with a 10 foot tap rule question

[superflycatday]

A 1200 ampere, copper THW main service has a 150 ampcalculated load added to a system . A tap will be made to feed this load. Thetap conductors will be 6 feet long and the tap will be done within the servicemetal enclosure. Following the NEC requirements for taps, the MINIMUM THW wiresize will be ?​

 

[roger]

Sounds like a study question, give us your answer and how you arrived at it then we can help you.

Roger

 

[superflycatday]

Sounds like a study question, give us your answer and how you arrived at it then we can help you.

Roger

Well not really sure what the answer is for this one or where to find this one so that's why I posted it .

 

[MAC702]

Agreed. Tell us how far you got before you got stuck.

 

[roger]

Well not really sure what the answer is for this one or where to find this one so that's why I posted it .

OK, go to 240.21 and try to work it out.

Roger

 

[petersonra]

A 1200 ampere, copper THW main service has a 150 ampcalculated load added to a system . A tap will be made to feed this load. Thetap conductors will be 6 feet long and the tap will be done within the servicemetal enclosure. Following the NEC requirements for taps, the MINIMUM THW wiresize will be ?​

Are they tapping the service conductors?

 

[infinity]

Are they tapping the service conductors?

Good question but does it matter with the 10' rule?

 

[petersonra]

Good question but does it matter with the 10' rule?

Nope. But how would one add a service rated disconnect inside the existing service enclosure that would meet the grouping requirement?

 

[infinity]

Nope. But how would one add a service rated disconnect inside the existing service enclosure that would meet the grouping requirement?

It could be adjacent to it and still be grouped in one location.

 

[petersonra]

It could be adjacent to it and still be grouped in one location.

then the tap conductors would not be contained within the service enclosure.

 

[infinity]

then the tap conductors would not be contained within the service enclosure.

Are they required to be? The OP said that the tap will be within the "service metal enclosure"

 

[petersonra]

I seem to recall that in some cases the tap conductors have to be fully enclosed in one enclosure to meet the 10-foot rule. the other thing is it seems to me that I recall the rules are slightly different for field Taps as opposed to factory taps.

 

[texie]

I'm confused here. I took the OP to mean he was tapping service conductors where the tap rules don't even apply. Of course the connectors would have to be suitable, etc but not tap rules.
Am I missing somethig here?

 

[infinity]

I'm confused here. I took the OP to mean he was tapping service conductors where the tap rules don't even apply. Of course the connectors would have to be suitable, etc but not tap rules.
Am I missing somethig here?

Sounds like SEC's but it's somewhat unclear. One point I was making is that in this case with SEC's or with the 10' tap rule the conductors would be the same size since they're leaving the enclosure.

 

[don_resqcapt19]

Good question but does it matter with the 10' rule?

Yes, it does matter. The rules in 240.21(B) do not apply to "tap" connections made to service conductors. The only rule for the service tap is that they are sized to the load.

 

[infinity]

Yes, it does matter. The rules in 240.21(B) do not apply to "tap" connections made to service conductors. The only rule for the service tap is that they are sized to the load.

Which is why in this case it doesn't matter. Load 150 amps, 10% tap rule 1200*10%=120 amps so the minimum conductor size is 150 amps whether it's a tap or not.

 

[LarryFine]

And this, ladies and gentlemen, is why simple questions often result in long threads!