I need to do some electrical work on a circuit in my home. One of the outlets on the circuit has a UPS battery backup plugged into it. The UPS is tucked away behind a lot of other equipment, so I'd rather not have to unplug it if its not necessary. Is there a risk of the UPS "leaking" (or whatever the term would be) back onto the circuit when the breaker is tripped? That is, for safety, should the UPS be unplugged before I work on the circuit?
Specifics in case they matter:
- I am replacing some switches for lights on the same circuit as the UPS
- the switches do not control the outlet the UPS is plugged into
- the UPS is a bXterra BM1500AVRLCD (1500VA)
Best Answer
While this should be acceptable, I have personally found a UPS which backfed 240AV out its input pins. I only found this out when brushing against the exposed pins on the wall plug - That UPS went straight in the junk pile!
In short, when dealing with mains power, make no assumptions. Use a non-contact voltage indicator or a plug-in lamp or even a voltmeter, to check your assumptions.
In your case, the switches are on a different circuit, and you will shut off the breaker to that circuit. When you open the switch plate, check for voltage immediately. And if its still live then stop and re-evaluate.