250-122 NEC Parallel

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aldondm

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Boston Ma
We have an installation which we installed 3 MC risers in parellel 400-4 with a 1/0 ground Al conductors. The inspector is saying we cannot parallel the 3-1/0 to satisfy table 250-122 800 amps? I am reading 250-122 A and F please advise, this is installed and ready to power up.
Also we used cable tray to support the cable from the MDP to the riser so worst case we should be allowed to install seperate conductors?


Thank you any positive information you could forward would be appreciated.
 

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aldondm said:
We have an installation which we installed 3 MC risers in parellel 400-4 with a 1/0 ground Al conductors. The inspector is saying we cannot parallel the 3-1/0 to satisfy table 250-122 800 amps? I am reading 250-122 A and F please advise, this is installed and ready to power up.
Also we used cable tray to support the cable from the MDP to the riser so worst case we should be allowed to install seperate conductors?


Thank you any positive information you could forward would be appreciated.
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For 800A, the EGC size is 3/0 AL. For paralleled conductors in separate raceway or cable, you have to run full size EGC's in each raceway or cable. See 250.122(F)

PS: the cable tray only makes a difference when using single conductors.

PPS: Welcome :thumbsup:
 
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What type of facility is this? With all the meter sockets I'm inclined to think residential. Not specifically prohibited for residential, but 392.60 permits cable tray to be used as an EGC. You would have to not use the EGCs in the cables... and the inspector would have to buy off on the "continuous maintenance and supervision ensure that qualified persons service the installed cable tray system and the cable tray complies with provisions of this section."

Also, is that steel or aluminum cable tray. If steel, you are SOL regardless [Table 392.60(A)].
 
250-122 NEC Parallel

I/we where affrid you where going to say that...we are reaching for a cost effective fix...the cable tray option is not there...and yes this is a condo set up...thanks
 
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