I have a 12V light in the ceiling of a utility room that can take about 20 seconds to turn on. Once it is on it will turn off and back on quickly until it is left off for a while. It is under a flat roof so I have very limited access to the wiring. Is the mains to 12V converter likely to be faulty? I occasionally see some condensation in the bulb could this be the cause? What is the usual way of accessing electrics under a flat roof? Take the roof off or ceiling down? Either way seems quite drastic.
12V Light Slow Turning On
- Thread starter DavidAC123
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Often these units can take a few seconds to fire up, but not that long.
Going on and off suggests it is overheating, or has been damaged by overheating and has a bad connection somewhere.
The lamp condensation should not make any difference to the running of the converter.
You shouldn't need to remove the roof or the ceiling to get to the wiring: it should all be there when you drop the fitting down.
There should be good ventilation, however. I suspect there may not be.
It could be you have insulation up there. Given it is a flat roof, this could be awkward to rectify.
You should also have good headroom between the top of the fitting and the roof structure.
All these installation measures are to prevent overheating and fire risk.
If there is minimal headroom, you could fit a shallower, cooler running fitting like an LED unit, but it should still be installed in accordance with regulation, and not just the electrical ones.
Thank you to Ban for a list of helpful docs posted in another thread:
Going on and off suggests it is overheating, or has been damaged by overheating and has a bad connection somewhere.
The lamp condensation should not make any difference to the running of the converter.
You shouldn't need to remove the roof or the ceiling to get to the wiring: it should all be there when you drop the fitting down.
There should be good ventilation, however. I suspect there may not be.
It could be you have insulation up there. Given it is a flat roof, this could be awkward to rectify.
You should also have good headroom between the top of the fitting and the roof structure.
All these installation measures are to prevent overheating and fire risk.
If there is minimal headroom, you could fit a shallower, cooler running fitting like an LED unit, but it should still be installed in accordance with regulation, and not just the electrical ones.
Thank you to Ban for a list of helpful docs posted in another thread:
Thank you. It is only going on and off when I turn the switch on and off. What I was trying to say was after being off for some time it will take possibly 20 seconds for the light to come on after I turn the switch on which is a pull cord. The light will then turn off and back on as soon as I turn the swith off and on. If I leave it off for a while it will be back to taking time for the light to come on after I turn the swich on. Does this still suggest the 12V transformer?
I can get to the transformer itself but not to the other end of the mains wire. I could possibly cut the mains wire close to the transformer and connect another transformer with a terminal block. I would do this with the mains turned off of course.
The flat roof is nearing the end of its life and I will probably get it recovered within a couple of years. Another light under the flat roof does not come on at all, there is no power to the bulb. There is another close to it on the same switch that does come on so it is not so bad.
I can get to the transformer itself but not to the other end of the mains wire. I could possibly cut the mains wire close to the transformer and connect another transformer with a terminal block. I would do this with the mains turned off of course.
The flat roof is nearing the end of its life and I will probably get it recovered within a couple of years. Another light under the flat roof does not come on at all, there is no power to the bulb. There is another close to it on the same switch that does come on so it is not so bad.
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You need to look for a bad connection somewhere.
Might as well start at the switch. Unless there are other lights on that switch that come on immediately.
Might as well start at the switch. Unless there are other lights on that switch that come on immediately.
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Duff lampholder.
Thank you. I will see if I can get to the mains going into the transformer and measure it and the output. I think I will have to cut the transfomer mains wires though and reconnect it or a new one with a terminal block. I could not get to the end of the transformer mains lead.
Betcha it is. 
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