ECN Forum Forums General Topics of the Trade General Discussion Area florescent lights working on 90 volts

If it's a standard 80% breaker that is amazing, but you have to wonder if all of the lights are on all the time too.

I am so familiar with 100% breakers because I spec them so often, most recently on a bunch of PV jobs. The switch gear for a large portion of these cookie-cutter jobs we've been doing has several 100% rated 500 amp breakers with parallel 250's to large inverters, the inverters have a maximum output of 440 amps at 480 so the breakers are fine. If we used 80% breakers we'd have to use parallel 350's and upsize the conduit and that would quickly cost more than the additional $500 or so for the 100% breaker since the distances between the inverters and switchgear are usually 200-400'.

We had a vendor supply us with an 80% breaker by accident this summer and when the array went online everything was fine until August when it tripped a dozen or so times. Every time the meter recording showed it tripping between 402 and 405 amps, right at the 80% rating.

So, having an 80% 20 amp breaker hold 19 amps for 2 years is exceptional IMO.

That circuit should really be split into 2 circuits IMO, but I don't think the circuit length and load is the issue on the 90 volt readings unless the total circuit length is around 500+ feet which it doesn't sound like it is.