I have a customer that is feeding a UPS with an ATS. He wishes to put the OCP (over current protection) for the UPS on the ATS input. This would require OCP for both sources to the ATS. Question: does the NEC allow you to put the OCP at the ATS input? The UPS is provided with an internal disconnect.
OCP at ATS input
- Thread starter flownder
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Re: OCP at ATS input
The code doesn't require a local disconnect for a UPS or an ATS, but it does require the UPS and ATS to be protected by an OCPD. Seams ok to have the OCPD on the two line sides of the ATS inputs to protect both the ATS and UPS. Be sure the OCPD is set to protect at a trip value equal to or lower than the ratings of the ATS and UPS. Many like (not require) a OCPD at the UPS for maintenance.
The code doesn't require a local disconnect for a UPS or an ATS, but it does require the UPS and ATS to be protected by an OCPD. Seams ok to have the OCPD on the two line sides of the ATS inputs to protect both the ATS and UPS. Be sure the OCPD is set to protect at a trip value equal to or lower than the ratings of the ATS and UPS. Many like (not require) a OCPD at the UPS for maintenance.
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