Is a UPS a "Separately Derived System"?

[Royalder]

We routinely use a 120v UPS in our control panels. The kind with receptacles on the load side. Is this classified as "Separately Derived", and do we have to somehow tie the load side neutral to the the enclosure ground?

Also, as a standard feature, our panel's control power is tied to the UPS via plug and cord. The plug end plugs into one of the UPS receptacles, and the other end is stripped back and landed on terminal blocks, for distribution of backed-up power within our control panel. The UPS power cord plugs into a receptacle, which is wired to a branch circuit outside our panel. If the UPS fails, the customer can unplug the UPS and remove it, and then the hardwired plug and cord can then be plugged into the now empty recepticle, and power is restored.

If we had wired the UPS as separetly derived, we would now have a neutral to case bond (a vilotation).

 

[Smart $]

We routinely use a 120v UPS in our control panels. The kind with receptacles on the load side. Is this classified as "Separately Derived", and do we have to somehow tie the load side neutral to the the enclosure ground?

Also, as a standard feature, our panel's control power is tied to the UPS via plug and cord. The plug end plugs into one of the UPS receptacles, and the other end is stripped back and landed on terminal blocks, for distribution of backed-up power within our control panel. The UPS power cord plugs into a receptacle, which is wired to a branch circuit outside our panel. If the UPS fails, the customer can unplug the UPS and remove it, and then the hardwired plug and cord can then be plugged into the now empty recepticle, and power is restored.

If we had wired the UPS as separetly derived, we would now have a neutral to case bond (a vilotation).

You left out the key word here... Seperately Derived System. Your use of the UPS is not as a power distribution system, but rather enhancement of receptacle supplied power. Additionally, if the unit is furnished with cord and plug, and UL listed as such, any bonding of the output other than the grounding conductor on the utilization end of a cord and plug connected device/equipment would invalidate the listing.

 

[petersonra]

they are generally internally bonded.

 

[ron]

Are you deriving a neutral in that type of line interactive or off-line type UPS?
I've not done any experimenting with one, but I would bet that when the UPS is feeding utility power or inverter power, the neutral is still intact.
If that is the case, then I vote for not separately derived, and no neutral to ground bonding on the UPS.

 

[dereckbc]

If this is your standard consumer grade plug-n-cord standby UPS, it is not likely SDS. Or at least never seen one yet that is SDS.

You don't get into the SDS UPS until you get in the higher-end dual conversion types rated above 1500 VA, and require premis wiring. It will be obvious from the installation directions either way.