distros

[LD4tw]

Hey Guys,


Just a quick question. If i had a 400 Amp 3 phase service, i can technically t-tap the output of that and go in to 2 x 250Amp 3 phase distros and everything should be fine. Is that a correct assumption. Thanks for the help in advance!

 

[ScottT]

2 x 250 = 500
500 > 400

I would assume no, but someone else will be along shortly...

 

[Edrick]

You can do it it's commonly done but you'll still be limited to the breaker rating.

 

[avkid]

As long as the disconnect is fused or has a breaker go for it.

 

[willbb123]

You are still limited to the 400amps, but you can break it out as many times as you want.

 

[Traitor800]

As long as the disconnect is fused or has a breaker go for it.

And make sure all your cable is 4/0

 

[STEVETERRY]

Hey Guys,


Just a quick question. If i had a 400 Amp 3 phase service, i can technically t-tap the output of that and go in to 2 x 250Amp 3 phase distros and everything should be fine. Is that a correct assumption. Thanks for the help in advance!

Yes, you can do that under the "tap rule" of NEC section 520.53(H)(3) and (4). If you are using conductors rated at less than 400A between the 400A service and the 250A distros, you are limited to length and routing by these sections:

(3) Supply Conductors Not Over 3.0 m (10 ft) Long. Where supply conductors do not exceed 3.0 m (10 ft) in length between supply and switchboard or supply and a subsequent overcurrent device, the supply conductors shall be permitted to be reduced in size where all of the following conditions are met:

(1) The ampacity of the supply conductors shall be at least one-quarter of the current rating of the supply overcurrent protective device.

(2) The supply conductors shall terminate in a single overcurrent protective device that will limit the load to the ampacity of the supply conductors. This single overcurrent device shall be permitted to supply additional overcurrent devices on its load side.

(3) The supply conductors shall not penetrate walls, floors, or ceilings or be run through doors or traffic areas. The supply conductors shall be adequately protected from physical damage.

(4) The supply conductors shall be suitably terminated in an approved manner.

(5) Conductors shall be continuous without splices or connectors.

(6) Conductors shall not be bundled.

(7) Conductors shall be supported above the floor in an approved manner.

(4) Supply Conductors Not Over 6.0 m (20 ft) Long. Where supply conductors do not exceed 6.0 m (20 ft) in length between supply and switchboard or supply and a subsequent overcurrent protection device, the supply conductors shall be permitted to be reduced in size where all of the following conditions are met:

(1) The ampacity of the supply conductors shall be at least one-half of the current rating of the supply overcurrent protective device.

(2) The supply conductors shall terminate in a single overcurrent protective device that limits the load to the ampacity of the supply conductors. This single overcurrent device shall be permitted to supply additional overcurrent devices on its load side.

(3) The supply conductors shall not penetrate walls, floors, or ceilings or be run through doors or traffic areas. The supply conductors shall be adequately protected from physical damage.

(4) The supply conductors shall be suitably terminated in an approved manner.

(5) The supply conductors shall be supported in an approved manner at least 2.1 m (7 ft) above the floor except at terminations.

(6) The supply conductors shall not be bundled.

(7) Tap conductors shall be in unbroken lengths.

ST