I find I have a major disagreement with the "instructions" accompaning most 480V 4 wire gneset suppliers, and several different opinions form various AHJs on how to run and bond the neutral of the genset.
I construct quite a number of sewage pump lift stations. Regardless of wether the utility is suppling 4 wire power, the neutral is never used. Hence the neutral is terminated and bonded at the first OCPD. The genset is always a permanently mounted, 4 wire device, AND has it's own OCPD mounted on the frame.
The ungrounded three phase conductors from both sources are brought to an ATS.
In the past, I have always terminated and bonded the genset's neutral (as it is unused by the premisis equipment) on the unit's frame, adjacent to its OCPD, and run an equipment grounding conductor back to the ATS and bonded to the premisis grounding system. This would seem to provide a single path for fault current back to the genset if a ground fault occurs, regardles of wether it's at the utilization equipment or the genset itself.
As the neutral is not used:
1. Is it still correct that this is not a SDS?
2. Why should a neutral be run from both the utility and genset to the ATS and inter-connected when it's not utilized by the premisis equiipment?
3. Is an additional grounding rod & GEC required at the genset, when it's already interconnected to the premisis' system via an EGC sized to the genset's OCPD?
I construct quite a number of sewage pump lift stations. Regardless of wether the utility is suppling 4 wire power, the neutral is never used. Hence the neutral is terminated and bonded at the first OCPD. The genset is always a permanently mounted, 4 wire device, AND has it's own OCPD mounted on the frame.
The ungrounded three phase conductors from both sources are brought to an ATS.
In the past, I have always terminated and bonded the genset's neutral (as it is unused by the premisis equipment) on the unit's frame, adjacent to its OCPD, and run an equipment grounding conductor back to the ATS and bonded to the premisis grounding system. This would seem to provide a single path for fault current back to the genset if a ground fault occurs, regardles of wether it's at the utilization equipment or the genset itself.
As the neutral is not used:
1. Is it still correct that this is not a SDS?
2. Why should a neutral be run from both the utility and genset to the ATS and inter-connected when it's not utilized by the premisis equiipment?
3. Is an additional grounding rod & GEC required at the genset, when it's already interconnected to the premisis' system via an EGC sized to the genset's OCPD?
