Just installed a lighting contactor for parking lot lights at 480 volts. I used a 277 volt coil using the line 1 voltage of 277 volts to send thru a photo-cell on the line side. When the photo-cell is activated it would pull in the contactor on the load side, turning the lights on. When testing this after completion by putting the box over the cell to similate darkness, the photo-cell was blown apart after the lights had switched off for approximately 20 - 30 seconds.
One side of the coil was connected to a common as well as the photo cell white wire being connected to the same common. Any ideas as to why it blew apart? Any suggestions for a remedy?
Thank you.

My first thought?

Was it a 120v photo-cell?

TE

The photo-cell was a 120/277 rated appliance.

Just finished a job like that. (see the job comes together thread of a few weeks ago.)Make sure that you are running the other side of your sensor to the neutral line. If it's not your putting 480 across the light cell. Sorry if I'm being elementry but you always double check yourself when the troubleshooting starts.
Next question, where in the scheme of things is the light sensor? Is it in a building where you are pulling the power, or is it mounted to one of the light poles. If you have room for it I think I would recommend a transformer to take your control voltage down to 110 or less. That way the guy behind you changing the sensor doesn't get a rude suprise.
Good luck, troubleshooting is always the fun part.
Trainwire

Was the photocell rated for an inductive load?
The fact that the cell was damaged by switching OFF suggests that the collapsing magnetic field may have damaged it.

[This message has been edited by Redsy (edited 10-01-2002).]

Never forget--it's highly desirable to keep molten copper from splattering on you or your clothes.

Hope there is a properly rated fuse in the control circuit. Like, say, a KTK-3R... I would not repower anything without a proper control-citcuit fuse.

It's just a careful process of elimination.

Was it a plugin photocell? Bench test the new photocell.

Trace all wiring. Check voltage with the cell unplugged. Then connect a milliammeter in the line/usually "black" lead of the cell and carefully power it.

It is remotely possible the cell was defective, but make damn sure everything else is OK before the second "test."




[This message has been edited by Bjarney (edited 10-01-2002).]

We installed a new Intermatic photo-cell rated for only 277 volts and it held. Apparently, the previous cells were defective. They both blew out at the photo eye itself.