240.21(B)(1)

[Tim11]

I am curious whether or not 310.15(B)(7)(2) or (3) applies when sizing a 200 amp feeder and 2-200 amp feeder taps when utilizing the 10' tap rule in a single family dwelling?

10' tap rule. 240.21(B)(1)(1)(a) basically states that the tapped conductors need to be sized no less than the ocpd that the tap conductors land on. So in that case If i had a 200 disconnect. i would need 3/0 Cu which is good for 200 amps at 75 degrees for my feeder tap.

Could be overthinking this but if 310.15(B)(7)(2) applied than you would only need a 4/0 Al or 2/0 Cu for your feeder and feeder taps like you would need for a typical 200 service. Am I on the right track here? Hahah.

 

[ActionDave]

Could you please update your profile to indicate how you are related to the electrical industry.

 

[Tim11]

Yeah, no problem.

 

[ActionDave]

You don't have a tap unless the wire has its overcurrent protection at the end of the run instead of the source.

Tap Conductor. A conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.

If you have 2/0 Cu wire fed from a 200A breaker then you just have conductors, not tap conductors.

 

[Tim11]

Imagine a 200 amp Meter can with a 200 amp service rated main breaker disconnect next to the meter and a 3R trough located beneath the main. The trough would serve the purpose for splicing and running a 200 amp sub feed to a barn as well as a 200 amp sub feed into the home within 10'. Wouldn't the feeder running to a barn in this case be considered an outside tap of unlimited length and the sub feed into the home be considered a tap if the panel inside the house has a 200 amp breaker? I was under the impression that the feeder tap into the home would need to be sized appropriately to provide overload protection and the main would already be protecting the feeders into the trough...

 

[Tim11]

You don't have a tap unless the wire has its overcurrent protection at the end of the run instead of the source.


If you have 2/0 Cu wire fed from a 200A breaker then you just have conductors, not tap conductors.

Maybe what I described is really just a splice for the feeder and not a feeder tap. haha . Not a code guru by any means. That is why I am seeking some input and searching through older threads.

 

[ActionDave]

In the NEC "tap" has a specific meaning. If you had a 200A disconnect with #4 Cu you would have a tap.

 

[electrofelon]

Imagine a 200 amp Meter can with a 200 amp service rated main breaker disconnect next to the meter and a 3R trough located beneath the main. The trough would serve the purpose for splicing and running a 200 amp sub feed to a barn as well as a 200 amp sub feed into the home within 10'. Wouldn't the feeder running to a barn in this case be considered an outside tap of unlimited length and the sub feed into the home be considered a tap if the panel inside the house has a 200 amp breaker? I was under the impression that the feeder tap into the home would need to be sized appropriately to provide overload protection and the main would already be protecting the feeders into the trough...

I know this wasnt your question, but check out 230.40 exception #3 where you can serve both the house and the barn with service conductors off a single meter.

 

[Tim11]

In the NEC "tap" has a specific meaning. If you had a 200A disconnect with #4 Cu you would have a tap.

Ok. thanks for the response. Just found my handbook.