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[5tratus]

Hi folks,

I'm here with a quandry and I'm hoping someone can help me to debug or troubleshoot what might be the problem, before I resort to hiring a sparky.

I've lived in this flat for 7 years, it had been newly refurbished when I moved in. After 3 years, the seldom-used bathroom extractor fan stopped working. I didn't pay any attention because I rarely used it. Now, I've started sharing my flat and would very much like it to work.

I checked to see if all the wires were secure in the fan, they were.
I turned all the power off, and then back on again, and flipped the isolator switch a few times.. nope.. no joy,
So, I bought a new timed extractor fan (the same kind - like-for-like), turned off the power, and installed the new one, triple checking that all the wires were just where they were supposed to be according to the instructions and according to how the old one was wired.

then I turned off everything and turned it back on again, and it still doesn't work.
There are no breakers thrown , I checked the isolator switch outside the bathroom door, it seems fine - there are no fuses in it, so it's not that. and I can't see any loose wires inside of it.

I crawled up in the attic, the wires haven't been chewed by squirrels or anything, they all seem to be intact and leading to where they should be.

What could be the problem? could it be that I need to replace the isolator switch outside of the bathroom door?

What could I check that I've forgotton?

thank you very much in advance for any help anyone can offer :-)

stratus

[ericmark]

When fault finding there are two methods.
1) Test likely fault areas.
2) Work step by step until fault is found.
You seem to exhausted 1) so now it's time to start on method 2) for that you will need some thing to test with.

The neon screwdriver will not test a neutral so it needs to be a two wire tester, some times one is lucky and you do find the problem with a simple neon screwdriver but they also generate a lot of false pointers.

There are loads of 2 wire testers the Martindale VI13800 is the industrial standard tester but there are many cheaper than that, a multi-meter can start at around £5. However the leads are often not suitable for mains use even when the meter they come with measures up to 1000 volts.

The first thing I would do is wire fan to a plug and flex and see it work, I have had faulty fans the wires in them are so thin very easy to get damaged.

With a multi meter you can work with power off, far safer that way, you measure resistance of fan then work back looking for same resistance, fans are often supplied from the lights, the ceiling rose gets rather crowded with wires and it is common to find the fault is in the ceiling rose.

[5tratus]

Hi!
thanks for your suggestions ericmark .

I think I can forgo testing the fan. since the chances that 2 fans are faulty are pretty small no?

I'll head over to screwfix today and pick up one of these http://www.screwfix.com/p/lap-mas830b-d ... _container and see if I can track down the fault. I hope it's nothing I can't fix myself.

yes, the fan is wired to the light so that when you turn the light on, the fan comes on, then it turns off 10 or 20 minutes after the light is off. the isolator is just outside the bathroom door.
the photo here is of the old fan, but the new one is identical and I put the wires in the exact same spot

cheers!
stratus

[ericmark]

Looking at the cables I would say likely some where a neutral and line wire have got mixed up. I hate using cables where the colours do not match the use, I can see at least on sleeve with correct colour, but it is so easy for a sleeve to fall off and be replaced on the wrong cable when no pin crimps are there to stop it falling off.

[5tratus]

hm... yes.. they could have gotten mixed up,

but if that were the case, how would the fan have worked fine for a few years?

I haven't touched the wires.

well. .I have my tester now, I'm going to watch some youtube videos about how to use it and then see

:)
5t.

[DIYDoctor2]

We sell Multimeters too - and all product sales from our DIY Superstore come with product support and project help - see the video on how to use the multimeter here https://www.diydoctor.org.uk/DIY-superst ... splay.html

[ericmark]

It is hard for me when I was taught from around 4 years old how to play with electricity. First lesson was I stuck two 6 volt bulbs across my electric train track, all was good until one failed and I replaced it with one of a different wattage.

My dad replaced the bulb for me as he said he had not taught me about wattage and resistance, but when the second one went I was told buy it myself I should have listened more carefully.

The problem with multi-meters is they test resistance with low current and low voltage, with mains stuff we (if we follow regulations) measure low ohms with at least 200 mA and high ohms or insulation with 500 volt.

The test in the video was one of the few where the ohm range of the multi-meter is good enough. Most meters have a continuity buzzer, but in real terms one could just as easy use a door bell, in fact we still call it belling out cables to find out which is which.

How he got the meter to stick to the wall I don't know? But that is a major problem using two leads and holding the meter at the same time you need three hands.

The other problem with multi-meters is selecting the wrong range. I wanted to do "A" digital photography it would cost over £100 but if I did three "A" levels then only £10 for all three so I did two other "A" levels picked what I thought would be easy so Physics and Maths. In the physics students were given multi-meters to measure volts and amps and you would not believe how many fuses were blown as they tried to measure volts with meter still on the amps range and these were "Advanced Level Students" would not like to see those at ordinary level?

With the 12 volt power supply all it did was blow the fuse, however with mains the same mistake can cause ionisation of the atmosphere which to put into layman's language is a big bang. Does not happen every time the error is made, but it is the electricians worse fear, and why we wear PPE when testing live circuits.

One way to ensure you never leave the meter on the amps range in error is not to have a wired amp range, the clamp-on ammeter does not require you to disconnect the wire to measure amps, it also has a volts range, and often frequency and ohms as well. The clamp to measure amps is also handy to hang the meter from something when your using it for other ranges.

One thing you need to watch is most cheap meter will measure mains, but the leads provided with the meter are not suitable. GN 38 (General Notice) lays out what the leads should have, this includes only 1 mm of metal showing, have fuses built into leads, having finger guards to stop your hand slipping down the leads, and a double insulated plug to go into the meter.

At around 14 I bought my pride and joy an AVO multi-minor. It cost a fortune to my mind around £15 which was a weeks wages in 1965. I fried it leaving it on the amps range. So I was no different, it taught me always to leave meter set to high volts range.

When my son started I lent him my AVO Mk8 back in 1982 that was £200 worth of meter, but it had all sorts of safety bits, cheaper meters just let out expensive blue smoke. Latter I got him a clamp-on meter like I used. Now he is also an electrical engineer. But early years back in 1992 I was glad I had fitted RCD protection to all circuits as he tripped them quite a few times when he was studying to become a Radio Ham.

My dad was a power station technical supervisor, my father-in-law electrical project director, my son-in-law studied electrical engineering in Turkey, the other one is into computers, so it is hard to recall a time when we did not know how to work with electric. I was taught keep one hand behind your back, it was an old method to reduce the effect of electric shock.

Hope you have watched your videos and now know how to use it?