I have an under-counter halogen light (jc / g4, 12 watts) that doesn't work.

If I remove the glass safety cover (might be called the lens) from the light socket then the light works fine, and will illuminate when I flip the switch. As soon as I replace the safety cover, the light stops working again.

The cover is made of glass, with a metal circle at its outer edge. The cover attaches to the socket by three L-shaped metal arms.

If I power on the light with the safety cover attached, it produces no light, but it makes a quiet clicking noise, about 1 click per second.

Does anyone know what's going wrong here, or how to fix it?

  • I would think that a halogen fixture for counter use and having a provided glass cover might have a safety interlock which would prevent the light from coming on without the cover in place (burn hazard, breakage hazard from liquid splash on the hot glass envelope). You have the opposite problem! Is the metal band at the edge just mechanical reinforcement or does it somehow signal that the cover is in place? Does it press on and hold in a tab? Commented Dec 5, 2016 at 18:11
  • so far as I can tell, the metal is just a way to hold the glass in place - I think it is not intended as a conductor.
    – NMcConnell
    Commented Dec 5, 2016 at 18:55
  • If the glass cover is tightly fitting, then the temperature would be pretty high in the enclosed space. Is there a venting flange which fits between the glass cover and the fixture? Or is the glass cover optional and if it is used, are there some openings in the fixture which one is supposed to open? The clicking sounds could be a thermal limit switch getting tripped. If the 3 L-shaped restraining hooks are deployed without the glass cover in place, does the light shine? Commented Dec 5, 2016 at 19:29
  • I don't think it's a temperature issue - putting the cover on causes the light to stop functioning immediately - there's no time for heat to build up. I think I'll probably just replace the entire socket - If I can find a same-size replacement, that will probably be easier than trying to figure out this weird issue. If I do replace, I'll take apart the socket after it's removed to see what sensitive internals might be contacted by the arms when they attach to the socket.
    – NMcConnell
    Commented Dec 7, 2016 at 18:39
  • 1
    Is it maybe pushing against the bulb?
    – SDsolar
    Commented May 7, 2017 at 22:34

2 Answers 2


Sounds like you have a connection problem. Ever try pushing on the light without installing cover to see if it will flicker or anything like that? This would indicate a loose wire connection.

  • I just repaired a fixture that used a similar ring to hold the lamp & reflector in place, if you have enough wire pull it out and check the 2 wires in the back of the socket. To keep the pressure off the socket I twisted the assembly so the wire was looped in a circle, not all bunched up and causing problems when assembled.+
    – Ed Beal
    Commented Mar 14, 2019 at 20:15

Clicking might indicate a defective thermal cutoff sensor if the light has one. halogen lights are very hot.

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