Reading 120VAC wire to gnd when disconnected

[ptonsparky]

So their is no ground fault clearing path? Using any of the equipment shown in 250.114 with that UPS would be a code violation

My Fluke T+ has a GFCI test button. Using that on the load side of the UPS trips the GFCI device that is ahead of it. Yes, the power is immediately switched to battery but why would it matter. We would need an additional fault to cause a problem. (Think ungrounded Delta)

 

[ptonsparky]

Fortunately for our OP, his circumstances do not fall under 250.114

 

[don_resqcapt19]

My Fluke T+ has a GFCI test button. Using that on the load side of the UPS trips the GFCI device that is ahead of it. Yes, the power is immediately switched to battery but why would it matter. We would need an additional fault to cause a problem. (Think ungrounded Delta)

There is just no provision for a receptacle with a grounding pin to not have an EGC unless there is GFCI protection.
I know how this works and without a second fault, you can't get shocked other than line to neutral, but portable generators with an unbonded neutral require GFCIs. This is no different.

 

[ptonsparky]

There is just no provision for a receptacle with a grounding pin to not have an EGC unless there is GFCI protection.
I know how this works and without a second fault, you can't get shocked other than line to neutral, but portable generators with an unbonded neutral require GFCIs. This is no different.

Simple enough. Don't use the APC unit I have in 250.114 circumstances. It wasn't designed for that. Directions on the unit say "for home or office use".

 

[don_resqcapt19]

Simple enough. Don't use the APC unit I have in 250.114 circumstances. It wasn't designed for that. Directions on the unit say "for home or office use".

I expect in both home and offices that UPS is use to supply information technology equipment.

250.114
(3)In residential occupancies:
a. Refrigerators, freezers, icemakers, and air conditioners
b. Clothes-washing, clothes-drying, and dish-washing machines; ranges; kitchen waste disposers; information technology equipment; sump pumps; and electrical aquarium equipment
c. Hand-held motor-operated tools, stationary and fixed motor-operated tools, and light industrial motor-operated tools
d. Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers
e. Portable handlamps

(4) In other than residential occupancies:
a. Refrigerators, freezers, icemakers, and air conditioners
b. Clothes-washing, clothes-drying, and dish-washing machines; information technology equipment; sump pumps; and electrical aquarium equipment
c. Hand-held motor-operated tools, stationary and fixed motor-operated tools, and light industrial motor-operated tools
d. Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers
e. Portable handlamps
f. Cord-and-plug-connected appliances used in damp or wet locations or by persons standing on the ground, standing on metal floors, or working inside of metal tanks or boilers
g. Tools likely to be used in wet or conductive locations

Information Technology Equipment (ITE).
Equipment and systems rated 1000 volts or less, normally found in offices or other business establishments and similar environments classified as ordinary locations, that are used for creation and manipulation of data, voice, video, and similar signals that are not communications equipment and do not process communications circuits. (CMP-12)

 

[ptonsparky]

Sounds right. Apply newer standards to older technology.

As far as the OP, hardwire it.

 

[tortuga]

Sounds right. Apply newer standards to older technology.

As far as the OP, hardwire it.

Generally speaking it seems to me a hardwired UPS meets the definition of Separately Derived System (SDS), especially when you look at the newer ones that are always converting AC to DC then back to AC. So it would be required to be grounded 250.21, though there is the usual exception for control circuits, but then you would need ground detectors.

 

[Doug_W]

This morning I switched the wires from the UPS side directly to the secondary of the control transformer and all the weirdness went away. The wire in question no longer reads 120VAC hot to ground.

The control scheme of the circuit worked fine before and is working fine now. The difference now is that when I shut off 2, 3 pole disconnects and a switch for the control power, there are no live wires.

Thanks to all who helped,
Doug