Metal halide lights

[labman]

I am working on some security lights. I notice they take a long time, 15 minutes? to come on. Should I be expecting to have to replace the ballasts soon?

I found a mess today. I had changed the bulb the other day in one, and it still didn't work. I decided today would be a good day to get back to it. It turns out, the ''new'' bulb wasn't any good either. Before I found that out, I discover the licensed person that took money to instal it, ran 8' of 2 conductor w/o ground SJT from a box out through a brick wall and into the box. It is only a 85 watt unit, so the wire was heavy enough. Instead of the 1/2'' conduit thread, the cast exterior box had a 3/16'' X 1 1/2'' slot. How are you supposed to seal the feed to that?

 

[JTK]

A metal halide lamp like that should take less than 5min from fire to full brightness. Make sure the ballast is wired properly for whatever line voltage is feeding it. I've seen fixtures setup for 240v & fed 120v do similar things.
G/luck
Joel

 

[labman]

Surely the guys that used SJT to feed the power wired the balasts right. Thanks for the tip, the power feed is 120. The one with the SJT was wired to give about 250V to the bulb. It lit up within minutes of being turned on. I will check the others.

Sounds like replacing the ballast would have worked, but it would be cheaper and easier to wire it right instead.

As a know working bulb, I moved one of the slow lighting bulbs to the non working fixture, and it lit up faster. That bulb is Ok, that fixture is OK. One down, 2 to go.

 

[sbc350gearhead]

Seal around the box with a thin bead of translucent RTV. Check voltage at the fixture, as you might have low voltage. Also........a hot MH lamp will take about 5-15 minutes to refire.

 

[tom slick]

quote:

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Sounds like replacing the ballast would have worked, but it would be cheaper and easier to wire it right instead.

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when you replace the ballast you'll have to "wire it right" anyway. the are somewhat universal and have different "taps" for various voltages i.e. they will run on 120, 208, 240 or 480 it just has to have the correct wires connected. ballasts for HID lights are really just a transformer and capacitor, they usually work, flash or they don't work at all. it is possible that the ballast was wired to use the 208/240 tap but was fed 120. i haven't seen what happens when they are wired that way but it would be very easy to do.