Bathroom extractor fan issues - advice for a newish kid on the block please :-)

[newspark70]

Hi folks,

This is my first post on EF,so go easy on me please ;-)

I'm having issues with an inline extractor fan I've installed at my own home. Before you scream "NO DIYers!", I'm NICEIC Domestic Installer scheme registered.

The nature of the problem is that despite wiring the fan up to accommodate the timer run on feature,and at the same time install it to operate independently of the main shower room light,the fan runs continuously and can only be operated by closing the fan isolator switch (and ultimately the switched fused spur unit) I've installed on this leg of the lighting circuit. Pull cord switch,while operating correctly,is ineffectual.

At this point an account of the installation method would be appropriate:

- Old pull cord switch operating main shower room lamp removed and common and switched line extended to new single pole switch located outside of the shower room to operate the main shower room lamp. (Two pullcords in the same room were not desirable and I require the fan to operate independently of the main shower room lamp.)

- Supply taken from an existing junction box on upstairs lighting circuit in loft space above shower room (not from the shower room ceiling rose) by way of 1.5mm T&E and connected to switched 3A fused spur unit in bathroom cupboard. Box trunking applied to cable for protection against mechanical damage.
- Supply then fed out of FSU to new pull cord switch and line terminated into common line terminal in pull cord switch.
- CPC terminated at pull cord switch earth terminal.

***1.5mm Three core and earth employed from this point onwards***
- Brown connected (tapped off) common line terminal at pull cord switch and terminated at incoming common line terminal of three pole isolator switch.
- Grey (sleeved blue) crimped to neutral from FSU then terminated at incoming neutral terminal of fan isolator.
- Black (sleeved brown) connected to L1 terminal of pull cord switch then connected to incoming L1 terminal of fan isolator.
- CPC connected to earth terminal in pull cord switch.

- Brown from L1 load side of isolator to common line terminal into common line terminal in four terminal junction box in loft space.
- Grey (sleeved blue) from neutral load side terminal of isolator to neutral terminal of junction box.
- Black switched line (sleeved brown) from L2 load side terminal of isolator to switched line terminal in junction box.
- CPC crimped to incoming CPC from pull cord switch and connected to earth terminal in junction box.

- Three core and earth flex from junction box to fan. CPC not terminated at fan as fan is Class II equipment,but if I sell this house one day,I don't want anybody connecting Class I equipment to a circuit offering no CPC continuity at the because they have no understanding or can't be bothered to wire in a length of new flex from the junction box to the fan. So it's there and will probably never be used anyway.

I've checked continuity of all conductors between the pull cord switch and the isolator. Operation of the pull cord switch results in voltage present on switched line at the isolator and ultimately at the switched line terminal (labelled 'LT') at the fan.

Problem summary:
Scenario 1: FSU closed,pull cord switch open and isolator closed = fan runs permanently and pull cord switch ineffectual. 239v between CL/E and CL/N.
Scenario 2: FSU closed,pull cord switch closed and isolator closed = fan still runs permanently with 239v between SL-E,SL-N,CL-E,CL-N.

This is a sanity check really. I don't see a reason why a timer run on fan that has common line,switched line and neutral feeds correctly terminated should run permanently when the pull cord switch operates switched live as designed and intended. And I've installed them before but never had this problem.

My suspicion is that the fan's a dud and while it looks like a timer run on fan with the expected L/LT/N terminals and timer control,it's been wired up during production as a manually operated fan.

Would be very grateful indeed for any input,because my sanity's about to fail. I always love being corrected,so by all means please do! ;-)

Sorry this was long,so thanks for reading.

newspark70

 

[decolad69]

I reality we are talking 3 wires ?

 

[telectrix]

disconnect all cables from fan and put into choc block. then, with the supply on and fan switch off, measure L-N ( should be 230V). and s/l-N ( should be 0V. if not, it's your wiring that's at fault). if so, then operate switch and see if you get 230V on S/L. if this is all OK, then it may be the fan at fault.

 

[londonfire]

Have you tried switching the live and switch live and seeing what happens? Have you tested for voltage on live and switch live with everything off. If you have a voltage on the switch line when everything is off you need to recheck all your connections

 

[gooner85]

how do you have voltage there when the FCU is switched off?

 

[londonfire]

As in the light drop your using to provide the switch line.

 

[newspark70]

Right, I did exactly what telectrix suggested. Tests came back good,so my wiring wasn't at fault. Rang up a fellow local spark who happened to have a different make of fan in his van stock. Luckily he was passing me on his way home for the bank holiday! I've literally just wired it straight in to test,but without connecting up the ducting. Works perfectly. I'll put this down to 'one of those things'. I've wired loads of these in and it just didn't make any sense. It's moments like this you can question your sanity. Clearly this nice Chinese example of a fan has been wired up for manual mode at time of production,despite the SL terminal and timer control being present,or,putting it bluntly,it's plain buggered Either way,it's going back.

Thanks for your input chaps. I was losing it there!

 

[Brendan976]

The original fan, was it a humidistat by any chance? If so they need adjusting as they will auto start, and turn off, but, may run longer than your timer if there is too much moisture in the air or the adjustment is too low and it determines to much moisture.
Ben

 

[newspark70]

The original fan, was it a humidistat by any chance? If so they need adjusting as they will auto start, and turn off, but, may run longer than your timer if there is too much moisture in the air or the adjustment is too low and it determines to much moisture.
Ben

No Brendan,nothing as fancy as that. Bog standard inline fan with timer run on