I just replaced 12v halogen with 12v Led bulbs on two separate recessed lighting circuits. One has 9 lights, one has 5. On each set of lights, a single bulb is not coming on at the brightness of the others, it's significantly less bright.

I've swapped bulbs so I know it's the specific can location, not the bulb.

I also measured voltage at both the problem locations at it's showing 12v.

These are not on a dimmer.

What should I check next?


  • any way of checking polarity + vs -? I wonder if that one is reversed. Commented May 5, 2020 at 1:50
  • Is that can significantly hotter, e.g. above a furnace or stove? LED's are heat-sensitive. Also check for bad connections, e.g. loose wires or terminals, or aluminum wiring, which can build up a surface oxide. Commented May 5, 2020 at 5:16
  • 1
    I would be cleaning the contacts, halogen lamps original to the system crest a lot of heat and many times form oxides that may be limiting the voltage to the lamp even though your meter reads proper voltage.
    – Ed Beal
    Commented May 5, 2020 at 14:46

1 Answer 1


Thanks all. This did turn out to be an issue with some of the connections. I pulled the cans out of the ceiling (no attic access) and checked the wiring. On both of the troubled cans, the connection between the socket wires and the 12v lines coming out of the transformer looked burned out. These were factory connections, not wire nuts. I cut those out, reconnected the lines and all was good. Thanks again.

  • Glad to hear you got it figured out, and thanks for coming back to post this as an answer! Please click the "check mark" next to this answer so that others know that this is an answered question and so the system doesn't keep bumping it to the top of the list.
    – FreeMan
    Commented Jun 5, 2020 at 18:37

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