We are proposing to use one 4/c-350 MCM type G cable with two of the 4 conductors paralleled with the other two, thereby increasing the effective capacity from the typically rated 335 Amps per conductor to 670 Amps for the cable for a single phase, neutral plus hot leg circuit. This cable typically incorporates 4-1/c #1 "grounding" wires which obviously are intended to be paralled together at the source and load ends onto a ground bus. We would select the circuit breaker feeding this cable to have a fixed overcurrent rating of 700 Amps.
For paralleled conductors, the NEC would require a #1/0 grounding conductor from Table 250.122 based on an 800 Amp circuit breaker since there is no listing for a 700 Amp size. There is also the rule that grounded conductors cannot be paralled if smaller than 1/0, but Para 310.4 seems to group "grounding" conductors under the same rules as "grounded" conductors, thereby prohibiting the paralling of the #1 "grounding" conductors in the standard cables as manufactured.
This would appear to conflict with the manufacturer's intent that the standard three or four "grounding" conductors built into a standard cable can be paralled together even though the wires are sized less than 1/0 AWG.
Does anyone have experienxe with haow an inspector might approach this question? Or are there any NEC violations by using the 3-1/c #1 wires as the "grounding" conductor?
For paralleled conductors, the NEC would require a #1/0 grounding conductor from Table 250.122 based on an 800 Amp circuit breaker since there is no listing for a 700 Amp size. There is also the rule that grounded conductors cannot be paralled if smaller than 1/0, but Para 310.4 seems to group "grounding" conductors under the same rules as "grounded" conductors, thereby prohibiting the paralling of the #1 "grounding" conductors in the standard cables as manufactured.
This would appear to conflict with the manufacturer's intent that the standard three or four "grounding" conductors built into a standard cable can be paralled together even though the wires are sized less than 1/0 AWG.
Does anyone have experienxe with haow an inspector might approach this question? Or are there any NEC violations by using the 3-1/c #1 wires as the "grounding" conductor?
