tap question

[fireryan]

Is it permissible by code to come out of a 200 amp panel from the feed thru lugs and run to a 150amp panel with a main breaker?

 

[augie47]

as long as you follow the guidelines of 240.21 (length, etc)

 

[raider1]

What size conductors would you run from the 200 amp panel to the 150 amp main breaker in the second panel?

Chris

 

[infinity]

What size conductors would you run from the 200 amp panel to the 150 amp main breaker in the second panel?

Chris

Good question. 200 amp conductors eliminate the tap rule requirement.

 

[fireryan]

they conductors would be 2/0 al. Can you please explain the 200amp tap rule

 

[cpal]

2/0 Cu is needs to be protected at not moer than 175A, if the second panel has 150 A ocpd then 1/0 Cu is ok. (75Deg).are you using Al or Cu??

 

[raider1]

they conductors would be 2/0 al. Can you please explain the 200amp tap rule

You could not use 2/0 AL conductors and meet the tap rules. 240.21(B) states the provisions of 240.4(B) (The next size up rule) shall not be permitted for taps. 2/0 AL has an ampacity of 135 amps at 75 degrees C so to meet the tap requirements the 2/0 wires must terminate in an overcurrent device with an ampacity equal to or less than the ampacity of the wires.

The reason that I asked what size the conductors are is if you used conductors rated at 200 amps you would not have a tap at all.

Take a look at 240.21(B)(1) through (5) for the feeder tap rules.

Chris

 

[infinity]

they conductors would be 2/0 al. Can you please explain the 200amp tap rule

You would need a conductor with an ampacity of not less than 150 amps. Since you mentioned aluminum you would need at least a #3/0 aluminum. Since your tap conductors are more than 1/3 the ampacity of the 200 amp panel you can use the 25' tap rule {240.21(B)(2)}. This will limit your tap conductors to 25' in length.