How can I keep my track lighting from catching fire?

January 17, 2008 8:46 AM

You are an electrician. But you are not my electrician. Question about low-voltage track lighting system inside.

So we've got this track lighting. It's divided in four sections, each on their own circuit; three of them have always worked fine, one of them keeps burning out. As in, literally, the connector that attaches the power-source wire to the rail itself heats up to the point where it visibly damages the rail, then the lights go out.

(There's a split wire that comes out of the ceiling; that goes into a fancy little two-sided metal clamp which then screws onto the light rail. The burning happens between the clamp and the rail.)

On the theory that the connector wasn't making solid contact with the rail, or was maybe shorting across, I did a little science experiment and ran some scrap copper wire from each side of the rail to each side of the connector. Result: light, and heat -- within a few seconds the point where the wire touched the rail was noticeably hot to the touch. I haven't yet tried replacing the clamp itself, since that would require, well among other things going out and buying a new one.

So (finally) the question(s): what could be causing it to heat up like that at the connection point? Is it likely to be a problem with the clamp itself, since that's where the heating is happening? Or am I looking in the wrong place entirely? If it is the connector that's the problem, would it be incredibly stupid to, as a stopgap, just remove it from the circuit entirely, and run the wire directly to the rail? (as in: do those connectors serve any purpose other than being cosmetic?)

posted by ook to home & garden (9 comments total)

How much lighting do you have on that one circuit? There's likely either way too much draw, or there's a short across the rails, somewhere in that track. If you can, try swapping out the connector - or the whole rail, they're easy to assemble and disassemble - with one of the tracks that work fine.
posted by notsnot at 8:59 AM on January 17, 2008

There are five lamps on each of the circuits, so I'm reasonably sure that's not it... you think it could be a short in the track itself, though?
posted by ook at 9:28 AM on January 17, 2008

it does sound like a loose connection. loose connections make for more resistance, the resistance is expressed as heat. poof -- burning. (i've seen actual fires caused by a loose connection that never blew the circuit breaker, because it never drew more than the breaker would allow.)

seconding the suggestion to swap it out.
posted by rmd1023 at 9:32 AM on January 17, 2008

Are the lights on this track noticeably brighter or dimmer when they're working than those on the other tracks? Are any individual bulbs noticeably brighter or dimmer than any other bulbs?
posted by dsword at 9:53 AM on January 17, 2008

Nope -- when it's working, they all look the same.
posted by ook at 10:07 AM on January 17, 2008

Check the resistance across the two sides of the track; there may be a partial short. If you don't have a voltmeter, you can get one for $10-20 at Radio Shack, Sears, etc., and are very handy to have around once you get one.
posted by Doohickie at 10:31 AM on January 17, 2008

(oh... and do this without the bulbs in the fixtures)
posted by Doohickie at 10:32 AM on January 17, 2008

Keep in mind that for a given wattage, lower voltage means higher amperage. For this reason, low-voltage lighting circuits are especially unforgiving of loose connections. Make sure the connections between wires, clamps and rails are clean and rock-solid.
posted by jon1270 at 12:35 PM on January 17, 2008

Turns out the clamp connector was corroded inside, probably from the first time it burned out -- so couldn't make a clean connection. I was able to work around it by sanding off the worst of the corrosion and putting some copper shim inside the clamp before tightening it down; seems to be working (at least, no heat so far.) One of these days I'll get around to buying a new connector.

Thanks for the help, everyone!
posted by ook at 2:10 PM on January 17, 2008