I am replacing a 3 phase 208 volt ups. The existing ups is fed with a 100 amp breaker. The new ups is fused at 63amps. My question is the conductors there now are sized #2 for the phase conductors but a #6 for the neutral. Is this ok concidering the neutral conductor has nearly no current on it?
Neutral sizing for a UPS
- Thread starter JdoubleU
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texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
I think we need more info. Are you referring to the input side?
I think you may not have a neutral conductor on the input side (depending on the UPS type). This is likely an EGC.
ceb58
Senior Member
- Location
- Raeford, NC
You need to read to mfg. instructions. All of the Eaton 9170's I have installed the instructions called for one size bigger wire on the OCP that the NEC. I.e.: #2 on a 100 amp breaker with no mention of reducing the neutral size.
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