Low voltage wiring query?

I have a set of 6 12v recessed lights in the kitchen. Each light is connected to its own transformer, reducing the voltage from 240v to 12v. My problem is that one of the lights has stopped working. I have replaced the bulb, but it makes no difference. I've checked that the bulb works by putting it in another light socket - and everything works fine. A voltmeter shows that the voltage coming out of the transformer on the light that doesn't work is 17v, whilst the voltage coming out of a transformer on one of the lights that does work is 7v (Assuming I'm using the voltmeter correctly - I'm no expert!). My question is - Is it surprising that 17v is coming out of a transformer which is supposed to reduce it to 12v? Would you expect the bulb to blow if this is the case (because it doesn't)....and would the higher voltage cause the light not to work? Any ideas/advice you can offer would be much appreciated. Cheers

As you have swapped the lamps around, and the lamps work but the fitting does not, this would suggest either the wiring from the transformer to the lampholder or the transformer is at fault. (You didn't say where you measured.)

Check the voltage at the lampholder by using croc clips on your meter probes and bits of paperclips - don't try this with mains voltages! If there is no voltage, replace the cables.

Measure the voltage with a lamp connected and again without. A problem that occasionally arises with transformers is that the insulation between the windings starts to break down. When this happens they may show a high off load voltage which disappears when a load (the lamp) is applied. If that is the case, replace the transformer and your light should work ok.

[Edited by amtodd on 18-11-2002 at 14:32 PM GMT]

Don't forget that some 12V lighting transformers are electronic, and don't show much of an output voltage until there is a load connected (and working)