Paralleled Feeders Question

Status
Not open for further replies.
G

GSXR600

Senior Member
Hi,
I am cannot find anything in the NEC that restricts the use of article 240.4B when sizing paralleled conductor. would it be acceptable to us 2 sets of 4/0 to feed 500 amps. I keep second guessing myself.
 
Parallel 4/0s can be protected by a 500 amp OCPD, but you have to make sure that the calculated load is 460 amps or less.
 
confirming.. parallel in two separate conduits or same conduit.. could make a difference depending on details.
 
don_resqcapt19 said:
Parallel 4/0s can be protected by a 500 amp OCPD, but you have to make sure that the calculated load is 460 amps or less.
Click to expand...
Ummmm.... not exactly!

1) Noncontinuous plus 125% continuous load current values must be 460A or less where the temperature limitation is 75?C.

2) The ampacity (i.e. after the application of any adjustment and correction factors) is not less than the calculated load current AND greater than the next lower standard OCP rating (i.e. >450A).
 
Yes, I should have included something about the ampacity of the conductor (ampacity as defined in Article 100).
 
Status
Not open for further replies.
Top