ECN Forum Forums General Topics of the Trade General Discussion Area 480v parking lot lighting

We reto-fitted parking lot lighting from 208v to 480v, one ckt. keeps shorting out. Wire is rated for 600v. Lights work for two months at a time. Any feed back will be welcomed.

what the oringail luminaire wired on 120 v or 208 volt??

and i will suggest to megger the line to find out sometime you will get a bad spot of wire.

rule of thumb anytime you increase the voltage on parking lot luminaire system is megger it first if the wire are fine otherwise replace it.

that useally take care of bad curpits with connection and who know what happend in the pipe as well

what the wattage on the luminaires now ?? and the voltage it is on now 277 or 480 ??

if the megger pass the test then you should amprobe it to check the current drawage make sure it dont get too much loading escpally with the MWBC set up

Merci , Marc

Such problems can be quite vexing.

What I ended up doing in a similar situation was to put in-line fuses on BOTH wires, at the base of the fixture. I was then able to identify the fixtures that were giving us trouble.

As already said by frenchelectrician, sectionalise and megger all cables concerned and check the insulation resistance between cables to lamps.
Hopefully you don't have breach joints in the SL circuits.
These usually get damp because of poor sealing of the outer sleeving.
The increased voltage will cause them to break down faster and hence intermittand faults once in a while.

From control point lightcell contactor, fit section fuses on each outgoing SL circuit.

Also check the overall loading per string of lights.

Fit fuses in each lamp acces cover if not already there.

I would account for all the runs of wires in case the origional circuit picked up an remote outlet or some other light like a lighted sign or something. Being that the voltage was boosted, if anything was left on circuit, it is safe to say it's toast. Eliminate the easy things first before megging the wires or adding fuses. Do you recall the weather conditions a few days before the outage(s)?