12v ventilation fan in bathroom

[PeterRiley41]

just moved into a 10 year old house and checking out all electrics the bathroom vent fan doesn't run when 3 pole isolating switch turned on. when checked at fan connection (ceiling mounted Mansford XF100LV) there's no power at terminal, one brown and one blue at connection block. assume there's a stepdown transformer in circuit and looking at the number of wires at back of isolating switch, 6 in all, could it be that the transformer is part of the switch?

 

[Spark123]

I don't think it will be part of the isolator switch, more likely a box hidden in the loft (or somewhere else) connected between the isolator and the fan.
When you measured the voltage at the fan did you have your meter set to AC?

 

[ban-all-sheds]

looking at the number of wires at back of isolating switch, 6 in all, could it be that the transformer is part of the switch?

What are those 6?

Where are they connected?

8 would be normal:

2 x Permanent Live
2 x Switched Live
2 x Neutral
2 x Earth.

 

[PeterRiley41]

looking at the number of wires at back of isolating switch, 6 in all, could it be that the transformer is part of the switch?

What are those 6?

Where are they connected?

8 would be normal:

2 x Permanent Live
2 x Switched Live
2 x Neutral
2 x Earth.

Thanks, yes there are 8, will check the loft to try and locate a transformer. Also I was checking for power at fan with electric screwdriver so probably wouldn't light up at 12v. Will get me an ac/dc tester.

 

[Spark123]

Oh right, a neon screwdriver will definately not work with a 12v AC SELV source, you need a multimeter.

 

[ban-all-sheds]

A multimeter, at least, is an essential tool to have if you want to work on your electrics. It is just as important to have that correct tool as it is to have screwdrivers to use on screws instead of the point of a vegetable knife, wirecutters to use instead of nail scissors, wirestrippers to use instead of teeth, and so on.

Neon screwdrivers are questionable from a safety POV as they use your body as a current path, and they are unreliable - to safely check for voltage you must use a 2-pole tester, such as a proper voltage indicator or a multimeter.



This looks ideal for a household starter set - multimeter, voltage indicator and dedicated continuity tester, all in a handy case: http://www.amprobe.eu/de_DE/showproduct/115/Junior-Set/

PDF brochure: http://www.amprobe.eu/de_DE/downloadfile/115/beschreibung_1/

All in German, unfortunately, as is the blurb on each product:

Multimeter: http://www.amprobe.eu/de_DE/showproductdata/487/Hexagon_55/

Voltage indicator: http://www.amprobe.eu/de_DE/showproduct/116/2000_α_(alpha)/

Continuity tester: http://www.amprobe.eu/de_DE/showproduct/481/TESTFIX/

but it is sold in the UK - the company is now owned by Fluke, and I guess they haven't got all the websites sorted out yet - contact them (http://www.fluke.co.uk) for info on where to buy.

Right now the English specs are still lurking on the Internet Time Machine from when Beha was an independent company:

http://web.archive.org/web/20060920022629/http://www.beha.com/files_uk/multimeter/93549.pdf


Also see another discussion here: http://www.diynot.com/forums/viewtopic.php?t=26282 It's a few years old, so specific model number advice may be obsolete (and prices will be higher), but the generic advice is still sound.