drktmplr12
Senior Member
- Location
- South Florida
- Occupation
- Electrical Engineer
I'm looking at Southwire HLX02XXH 3c/4c XHHW Power, 3xGW, Cont. Alum. Weld. Armor for 300 HP motors (361 FLA) using parallel #4/0 feeds. NEC 250.122 points to 310.10(H) which states parallel EGC shall be sized according to 250.122.
My interpretation is that i will need to specify a #3 EGC in each conduit in order to ensure a properly sized fault current path. My next best option is a 4/C VFD cable. Use the 4th as the ground. I think its pretty clear. My colleague feels that I may be getting overly technical and the parallel sheaths together with the concentric grounds are adequate. The product data states the aluminum sheath meets the grounding requirements of 250.122 in non hazardous locations. This would imply that the sheath has, as a maximum, the impedance of #4 copper since that would be the minimum ECG required for 230A of ungrounded conductors.
What does the forum think?
My interpretation is that i will need to specify a #3 EGC in each conduit in order to ensure a properly sized fault current path. My next best option is a 4/C VFD cable. Use the 4th as the ground. I think its pretty clear. My colleague feels that I may be getting overly technical and the parallel sheaths together with the concentric grounds are adequate. The product data states the aluminum sheath meets the grounding requirements of 250.122 in non hazardous locations. This would imply that the sheath has, as a maximum, the impedance of #4 copper since that would be the minimum ECG required for 230A of ungrounded conductors.
What does the forum think?
