Article 240.21 (2) Tap not over 25'

[ju]

I have a 1200 amp service with a 1200 amp main. A EC who needs a 200 amp service for a relay station which is on the roof about 200 feet away. He would like to tap off the 1200 amp bus on the load side of the main with 3/0 copper conductors and feed the new meter and then go to a 200 amp serviceable disconnect with 200 amp fuses. The conductors are located a little under 25 feet from the 1200 amp main to the meter. It is my opinion that this is in violation of Article 240.21(2)which requires the size of the conductors to be one third the rating of the overcurrent device. In my opinion, the conductors should be rated for 400 amps with a main of 400 amps and then continue on to the meter with 600 kcmil to the second disconnect. The second disconnect would then be fused for 200 amps using 3/0 copper wire to the panel on the roof. Can anyone help me ???? I would appreciate your input.

 

[eric64]

Re: Article 240.21 (2) Tap not over 25'

I agree with you on the need for the tap conductors to be 600kcmil copper ( 1/3 the rating of the device protecting the feeder conductors ). I do however think he would be able to supply a meter and 200amp disconnect as long as the total length of the tap conductors does not exceed 25 ft. The 200amp main will limit the load on the 600kcmil tap conductors. The only way he could do it the with 3/0 tap conductors is if the total length of the tap conductors is 10 ft. or less.