Bathroom pull switch - a couple of questions

[Rollerball]

I think the the pull switch in my bathroom is faulty - this evening I turned on the bathroom lights as usual but after a few seconds they went off. The pull switch clicks as it should, but no power.

Fuses in fuse box all checked and okay.

The bathroom lights are 12VDC spots - in my attic is a 240VAC to 12VDC transformer (I now forget the make and model - it is white, maybe DEF-105 or something likel that?). Checking with my multimeter there is no 12VDC output from this and also no 240VAC input. There is some very messy wiring in my attic (not done by me!) and from what I can tell the pull switch is switching on/off the 240VAC supply to the transformer (I had initially assumed that it would be switching the 12VDC output).

So, first thing to do I guess is to check if it is the switch at fault - I can disconnect it tomorrow and test with my multimeter with the continuity test across the relevant terminals.

However, if it is faulty I'll need to replace the switch - these are easy enough to obtain but just from looking online I see that they are available in different amperages such as 5A, 6A, 10A, etc - what am I likely to need? There are five 12VDC spots in the bathroom.

 

[sparkwright]

Between 5 and 10 amp is what you need, so any of those switches will be ok.

A soon-to-be-knackered transformer could cause the lights to go out unexpectedly.

One or more loose connections somewhere could also cause erratic behaviour, so check all connections.

 

[Rollerball]

Thanks.

There doesn't appear to be any mains voltage getting to the transformer which I why I'm assuming that the switch is possibly at fault (presumably the switch is operating the power to the transformer).

 

[securespark]

Could well be a loose connection in the pc switch.

 

[Rollerball]

Ta, I'll unscrew it tomorrow and check.

 

[securespark]

Turn off first!

If not, it could be there is a loose connection where the feed to the switch comes from (a junction box near the transformer?)

Or a loose connection in the live loop further back in the circuit.

 

[Rollerball]

Yesterday I checked back through the circuit but couldn't find any loose connections.

Don't worry, I will of course turn off the power before removing the pull switch.

 

[Rollerball]

I no longer think it's the light switch - turned off the power, got out the multimeter and set it to continuity test - measured between live and neutral - there was a beep. Pulled the switch cord, re-tested - no beep. Pulled the cord again - there's a beep. So it appears to be switching. Time for an electrician I think!

 

[PrenticeBoyofDerry]

Did you test the switching operation with the line and neutral linked.
As that is what I would be doing to test using your method.
You can test across the switch using continuity by putting the probes at common and L1/L2, doing this in the on/off position of the switch, this should confirm if the switch is operational.

 

[Rollerball]

I think that's what I did, not 100% sure now. Think i'll just get an electrician to sort it out as he'll no doubt isolate the cause in no time.