12 volt internal lights?!?

Hi all, 

I put my 12 volt toilet light on this morning in my ford transit Duetto, 94 and it suddenly went off when I turned another one on? I thought it would be a fuse problem but the other spot lights around the cab and sides still work? I thought they would be on a separate ring main but no, they are all on one ring main at 10 amps. All other 12 volt works......

Any ideas? 

Shaun

Upon doing the old dad test and hitting the bathroom light whilst shouting fxxxx bxxxxx it’s now come back on if it’s a lose wire and the connections broke why do the other lights still come on? 

Parallel not series wiring?

Sometimes the connections on the bulb/tube just get slightly oxidised, so cleaning those may help, using emery paper (or an old emery board).

Brilliant Roger thank you I’ll give that a try

And I have no idea what parallel or series wiring is lol.

The light in the bathroom of our Duetto was changed before we bought it. The damp from the shower corroded the connections. I am not sure what make of light was fitted originally but the replacement was a labcraft. It was not really suitable for the damp area. The connections required regularly spraying with contact cleaner..

"Parallel" means each lamp is fed by its own wiring from a  supply, if one fails the others should still work (as a rule! ) unless a fuse is blown. 
This is camper style wiring. 

"Series" is like old style house wiring ring mains and all lamps are wired one after the next, and if the circuit continuity is broken or the fuse is blown then all will fail. 

Hope this simplifed explanation helps

Martin

Thanks for correction ref ring main.
Guess thats why I failed Physics at A Level!
Camper wiring is also parallel 

I was attempting to illustrate that if one bulb fails they all fail, as continuity is broken in a Series circuit. 

Apologies for adding confusion to the topic.

Martin