Parallel Feeders into a single Feeder

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mull982

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I have multiple parallel feeders for a motor and I dont have enough room in the motor terminal box so am going to build a box to bring in these multiple feeders and then converge them into a single feeder to go to the motor terminal box. What is required for the ampacity of the single feeder to converge the multiple parallel feeders into the terminal box.

What section of the NEC will address this issue?
 
mull982 said:
I have multiple parallel feeders for a motor and I dont have enough room in the motor terminal box so am going to build a box to bring in these multiple feeders and then converge them into a single feeder to go to the motor terminal box. What is required for the ampacity of the single feeder to converge the multiple parallel feeders into the terminal box.

What section of the NEC will address this issue?
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I'm thinking they're branch circuit conductors and subject to the 125% motor FLA as determined by 430.6 (which goes over to Table 430.150)

Motor terminal housing info is at 430.12
 
480sparky said:
At least the ampacity of the parallel feeders, and no less than the OCPD.
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In this case the OCPD is a motor instantaneous breaker and you cant really size wire to these types of breakers due to the fact that they are adjustable and so forth. Did you mean size them no larger than the overload device? This would then be 125% of the motor FLA correct?
 
For instance if I had (3) sets of parallel 500 MCM's going from a VFD to a motor what size would I need to have the single set of cables going from a Junction Box to the motor terminal box located nearby?

Would I just need to cover the 125% rating of the motor on this circuit or cover the ampaicty of all (3) sets of 500's? I'm thinking the 500's were used for voltage drop and underground de-rating so no need to carry that ampacity from the JB to the motor. I cant see m anything in the code that seems to address parallel motor feeders.
 
mull982 said:
What is required for the ampacity of the single feeder to converge the multiple parallel feeders into the terminal box.
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The size or rating of the parallel sets has nothing to do with the answer. The size of the breaker or fuses supplying the conductors has nothing to do with the answer either.

The only thing that matters is the FLA from the tables in 430. Just size the single set of conductors per the FLA from the tables and add the 125%.

Lets say they over sized the parallel sets for voltage drop reasons, you could still reduce down to the bare minimum size conductors for the last few feet.

I would also look into using RHW power cable for its high flexibility.
 
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