UPS Disconnect Switch

[FaradayFF]

Hi gents,

Is there a requirement in NEC code to provide a disconnect switch at the input or output of UPS? If the UPS is in the same room as the panel feeding it and the load panel, you could theoretically use breakers in the panels to isolate the UPS for maintenance.

 

[ron]

There is nothing in the code for a UPS providing that type of guidance like it does for a transformer, motor, etc.

It would be manufacturer installation instructions or permit drawing guidance, but not a code requirement if it existed at all.

We often do not have an input or output disc on the UPS when the panel serving it or the load panel is in the same room.

 

[Jraef]

So long as you can fit a lock-out hasp on the panel mounted breaker. You can on most, but not all.

 

[brian john]

Ideally, the UPS would have an external or sidecar Bypass cabinet, if not at a minimum at should have input CB.

 

[JuliaTruchsess]

645.11 addresses UPSs in data centers, and refers back to 645.10, which states "An approved means shall be provided to disconnect power to all electronic equipment..." and furthermore 645.11 states that "The disconnecting means shall also disconnect the battery from its load".

 

[texie]

645.11 addresses UPSs in data centers, and refers back to 645.10, which states "An approved means shall be provided to disconnect power to all electronic equipment..." and furthermore 645.11 states that "The disconnecting means shall also disconnect the battery from its load".

This would only apply if the designer has elected to follow Article 645.

 

[ron]

645.11 addresses UPSs in data centers, and refers back to 645.10, which states "An approved means shall be provided to disconnect power to all electronic equipment..." and furthermore 645.11 states that "The disconnecting means shall also disconnect the battery from its load".

This would only apply if the designer has elected to follow Article 645.

Which happens very infrequently in the current new data center market (last 10 -15 years). Plenty in the old stockpile of infrastructure.

 

[JuliaTruchsess]

This would only apply if the designer has elected to follow Article 645.

I didn't know you're allowed to pick and choose which parts of the NEC you feel like complying with. What am I missing?

 

[wwhitney]

I didn't know you're allowed to pick and choose which parts of the NEC you feel like complying with. What am I missing?

See 645.4. It indicates Article 645 is an alternative set of methods that "shall be permitted". If you don't want the extra allowances that 645 provides, you don't need to comply with the extra requirements it imposes.

Cheers, Wayne