Mercury light puzzle?

[Cadillac STS]

I got some lights from Craigslist. They are from an old store or warehouse. They are on a stalk about 4 feet long and have a ballast and a 2 foot or so reflector. Not exactly sure they are mercury lights. They don't say on the outside. When turned on they start pinkish yellow for 5 minutes or so then glow a whitish with a little yellow. Clear glass bulbs. 250 watts each.

Here is the puzzle. I installed them in my pole barn one by one. The first four worked well all on the same circuit. I replaced the flood type bulbs I had there so all there was was the new lights. When I put on the fifth one then turned on the switch the first two lighted and the rest didn't. I turned off the switch and immediately disconnected the last one figuring maybe it was bad/shorted or maybe just too much for the circuit with all 5 on same one. With the fifth one disconnected the first two light but the other two do not light.

My plan is to disconnect each one not working and run current to them separately to see if they are still functional and go from there. Haven't done it yet with the heat here working high up in the space.

Anyone have any ideas about what may have happened? Too much current draw destroyed some of the lamps?

Any ideas on knowing which type of lamp they are?

 

[nehog]

Sounds like metal halide lamps, any marks or labels, either on the bulbs or the fixtures? Almost always both are marked so you get the correct replacement bulbs.

Sounds like you may have some bad connections.

I'd recheck all connections that you made, and I think you will find one is loose. If the lamps are 250 watt, then each fixture will draw about 300 watts. Four fixtures will draw 1200 watts (roughly, there are power factor issues too...) so adding the fifth light ups the circuit power to 1500 watts, and that may well be more than the circuit could handle at 120 volts. (For example, my 400 watt metal halide lamps are all wired 240 volts, with four fixtures per circuit maximum.) Of course, if these are multi-voltage ballasts then make 100% sure the right tap is being used!

Also, if the bulbs are not new, now is the time to invest in new bulbs! Old, tired bulbs don't fire off as well and don't put out as much light.

 

[Cadillac STS]

Bing Bing Bing

nehog guessed it right!

There was a loose circuit in one of the boxes. I used one of those new push in connectors for a box where you strip 3/4 inch of the romex and push it in. Guess they fail sometimes.

I'm going to leave max 4 lights on one circuit now.