I have several MR16 2 pin style light bulbs in my kitchen - The other day the trip switch for the light bulbs tripped when turning these bulbs on - I went and flipped the trip switch and tried again to the same result. This happened three times, the same number of times as the number of MR16 lights. Now the trip switch doesn't trip but also none of these bulbs turn on, and replacing the bulbs with new ones doesn't work. I don't know much (anything) about lighting, these bulbs were in my house when I moved in, and was wondering if anyone could help me work out why this is happening and what I can do to fix it.

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    It sounds like it might be best if you contact a local licensed Electrician. If by "trip switch", you mean circuit breaker. These are designed to "trip", when there is a problem with the circuit they are protecting. Resetting the breaker does not fix the underlying problem that caused the trip.
    – Tester101
    Commented Apr 22, 2013 at 11:20
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    or is this a thermal reset switch local to the lights? Some strips had these built it
    – HerrBag
    Commented Apr 22, 2013 at 11:30
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    What exactly is tripping? If this is a kitchen then you should probably have GFCI protected outlets that are designed to trip quickly at the presence of a short. They can sometimes start randomly tripping when they go bad. Did you try resetting your GFCI outlets? If this doesn't work then a DIY'er with electrical experience or a licensed electrician should try to diagnose. Commented Apr 22, 2013 at 11:30
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    Here's my guess. A short circuit condition developed for some reason. By repeatedly forcing the protective device to break the short circuit, it essentially got cooked to the point it no longer functions properly. Fortunately, it failed safe, not allowing any current no matter what. The short must be corrected, and the protective device probably needs to be replaced.
    – bcworkz
    Commented Apr 23, 2013 at 4:50
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    @maple_shaft I think UK use "RCB" where US use "GFCI". Commented Apr 23, 2013 at 10:51

3 Answers 3


You're using MR16 50W 12V Halogen Flood Reflector Light Bulbs is my guess. Some of these light fixture for these light bulbs have a small transformer (4 wires - 2 pri (blk & wht color) & 2 sec -- about 1 inch x 1-1/2 inch x 1/2 inch) for each light bulb. They cost as much as a light bulb (maybe more), My guess is this one was on its way out and is now open circuit.


Somewhere in your light circuit there was a short circuit that caused the breaker to trip. By repeatedly trying to reset the breaker, the point at which the fault occurred finally blew itself apart. Now instead of having a short circuit you have an open circuit. Proper troubleshooting will allow you to find the problem's location, but explaining this procedure is somewhat challenging in this forum.


You killed your breaker. And there was a fault that needed rectifying. It could have been one lamp that developed a short- which has since been replaced. Or a wiring short- which may still be there.

If you have a multimeter AND your old lamps see if any show a very low resistance compared with the rest of them.

If so your wiring will be OK, and all the same resistance lamps will be OK to use. If they all show the same resistance the wiring needs help.

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