QC Electrical Engineer

[LAPaglinawan]

Outstanding for a 99% design drawing.....Sirs I would like to ask if the 300mm.sq + 1-35mm.sq. gnd, single phase with 400 Amps breaker size, and demand load of 213, this cable has been rectified by the contractor without any information they installed 2 sets-4-150mm.sq + 1-25mm.sq gnd....is this acceptable and approved by NEC?,if yes which article and section? what are those issue in this action?...thank you!

 

[Smart $]

There are at least a couple problems with compliance with the NEC:

1) Metric wire sizes are not recognized by the NEC.
2) Consequently, insulation type is also not recognized; not NRTL listed.

That said, in theory, if a 300mm? wire has sufficient ampacity, paralleled 150mm? of the same insulation type will have greater ampacity.

However, if run in same conduit, that greater ampacity would have to be adjusted to 80%, assuming the 300mm? is a set of 4 and the neutral is not counted as a current-carrying conductor.

An obvious violation is is the two 25mm? gnd's. Assuming 35mm? gnd is the proper size for the circuit, it not only would be the proper size for a one-conduit run... but also the proper size in each of a paralleled two-conduit run.

 

[petersonra]

I agree with the second poster.