Author Topic: UK toilet extractor fan  (Read 5492 times)

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Online Gyro

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Re: UK toilet extractor fan
« Reply #25 on: August 20, 2021, 01:13:02 pm »
A 3A fuse will not prevent a fire however  :-// A 3A BS1362 will carry 6A indefinitely so over 1kW

Servicing doesn't require lighting from the existing electrical installation otherwise how would you service the lighting, or complete an installation before energised?  :o

I agree with you. I'm not arguing that it makes sense. Just that's the way it's currently done / written. I didn't bother following up the additional references in the video.

I suppose the onus is on the fan manufacturer to explain why they think a 3A fuse would make any difference to its safety.

The only thing I can possibly think of is that a fan might get wired in 0.5mm flex (there's no way you're ever going to squeeze solid 1mm or 1.5mm 3 core+CPC in there - certainly on a ducted one). This wouldn't be sufficiently protected by a B6 MCB under the regs though. Sorry, I'm grasping for explanations - not knowing what the fan instructions say about the size of cable, I can't say though.
Best Regards, Chris
 

Online themadhippy

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Re: UK toilet extractor fan
« Reply #26 on: August 20, 2021, 01:16:12 pm »
As usual Bigclive has already dissected one.
 

Online richard.cs

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Re: UK toilet extractor fan
« Reply #27 on: August 20, 2021, 01:29:21 pm »
Somewhere I have the reverse-engineered schematic of mine, from when I modified to trigger from a current transformer. Notable points:
  • It's a resistive dropper not a capacitive one.
  • The switched live goes straight into a high-value resistor, so there really is no need to worry about fusing on that input.
  • It's a quad-NOR configured as an RC timer, with a very high resistor value and a modest electrolytic, maybe 220 uF.
  • I seem to remember the capacitor is normally charged and discharges to start the time delay (which ends once refilled), this may be because keeping the electrolytic biased reduces leakage current which would otherwise affect timing.
  • The whole board is neutral-referenced.
  • A small triac in the neutral is used to switch the motor.
  • I can't really remember but I think the board may have been given a negative supply relative to neutral, so as to allow negative gate drive for quadrant 2/3 operation and avoid quadrant 4.
 

Offline MajorbobTopic starter

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Re: UK toilet extractor fan
« Reply #28 on: August 20, 2021, 04:44:39 pm »
Unfortunately, the IET wiring regs always defer to the manufacturer's instructions. If the manufacturer specifies a 3A fuse, then there must be a 3A fuse to meet the regs.

It's not quite phrased that way any more, since 18th edition it just says "shall take account of", meaning take note, but not necessarily follow. The wording was changed since so many import products had badly written or incorrect instructions.

A 3A BS1362 fuse will not offer any discrimination compared to a B6 MCB so it is not providing any electrical benefit, however if there is a warranty claim on the fan they may not offer the warranty if it is not installed according to their instructions.

An isolator for the fan is not a requirement either, since the MCB is noted as a suitable isolation device (Table 537.4)

So according to 18th edition I can ignore the manufacturers instructions?  Any repairs and maintenance can be done during the day with the whole circuit off.
 

Online Gyro

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Re: UK toilet extractor fan
« Reply #29 on: August 20, 2021, 07:10:09 pm »
'Ignore' sounds like a pretty extreme interpretation of 'take account of'. There are clearly going to be cases (a lot of Chinese manufactured light fitting for instance), where the installation instructions are going to be wrong for the UK - eg. Not including instructions for earthing metal fittings. Something like specifying a specific fuse rating are less open to interpretation.

What are you wiring the fan up with? will it directly accept standard 1.5mm2 PVC solid 3 core and earth? Edit: Ah, they do make it in 1mm2, I didn't think they did.


At the end of the day, I don't think anyone here is going to publicly tell you that you can ignore the manufacturer's instructions when personal safety, insurance etc. are involved.
« Last Edit: August 20, 2021, 07:28:55 pm by Gyro »
Best Regards, Chris
 

Online Zero999

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Re: UK toilet extractor fan
« Reply #30 on: August 20, 2021, 07:21:08 pm »
As usual Bigclive has already dissected one.

The values seem to be on the low side: 470µF & 440k. I'll have to do some calculations to see what the delay will be.
 

Offline floobydust

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Re: UK toilet extractor fan
« Reply #31 on: August 20, 2021, 07:51:31 pm »
How can you import and sell cheap chinese bathroom fans in the UK, when they have no safety or agency approvals? OP, ensure your product is legit.
Yet we're worried about fusing and the ET Wiring Regulations. Like a fox in the henhouse.

The Big Clive fan, wasting 1.2W all the time- looking at the cooked 22k resistor, phenolic pcb, unknown plastic housing (UL 94V??) it's your usual POS.
I've seen other fans with electronics such as MCU and PIR sensor, use instead a capacitive dropper.
The only safety component is the dropping resistor, hopefully they are infallible. Not so with thick-film TO-220 resistors for some reason, I've seen them go lower in value with abuse.
This looks like metal-oxide running hot 24/7 just to power a CMOS timer  :palm:
 

Online Gyro

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Re: UK toilet extractor fan
« Reply #32 on: August 20, 2021, 07:57:21 pm »
The values seem to be on the low side: 470µF & 440k. I'll have to do some calculations to see what the delay will be.

I think Clive is out on the pot value, he didn't measure it but said it was marked C05, so it might be 500k (or even 5M?). The 220k fixed resistor is a minimum value limiter, so I would expect the pot to be significantly higher (I'm not sure what the minimum and maximum times are).
Best Regards, Chris
 

Online Zero999

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Re: UK toilet extractor fan
« Reply #33 on: August 20, 2021, 08:45:13 pm »
The values seem to be on the low side: 470µF & 440k. I'll have to do some calculations to see what the delay will be.

I think Clive is out on the pot value, he didn't measure it but said it was marked C05, so it might be 500k (or even 5M?). The 220k fixed resistor is a minimum value limiter, so I would expect the pot to be significantly higher (I'm not sure what the minimum and maximum times are).
It looks like 605 to me, or perhaps 1605 which is 6M, or 16M. which are odd values, but wouldn't be surprising.

It took a screenshot and upped the contrast a little to make it clearer.
 
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Online Gyro

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Re: UK toilet extractor fan
« Reply #34 on: August 20, 2021, 09:03:47 pm »
Sounds right to me, I'd guess at 6M rather than 16.
Best Regards, Chris
 

Offline MajorbobTopic starter

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Re: UK toilet extractor fan
« Reply #35 on: August 21, 2021, 08:56:26 am »
'Ignore' sounds like a pretty extreme interpretation of 'take account of'. There are clearly going to be cases (a lot of Chinese manufactured light fitting for instance), where the installation instructions are going to be wrong for the UK - eg. Not including instructions for earthing metal fittings. Something like specifying a specific fuse rating are less open to interpretation.

What are you wiring the fan up with? will it directly accept standard 1.5mm2 PVC solid 3 core and earth? Edit: Ah, they do make it in 1mm2, I didn't think they did.


At the end of the day, I don't think anyone here is going to publicly tell you that you can ignore the manufacturer's instructions when personal safety, insurance etc. are involved.

Maybe "ignore" was the wrong terminology.  I'm asking here so clearly I have "taken account of" the instructions.  Its the cheapest fan B&Q had on their shelf so it not complete chinese rubbish.

I can't remember if I have 1 or 1.5mm t&e of the top of my head but the whole installation is brand new.
 

Offline Monkeh

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Re: UK toilet extractor fan
« Reply #36 on: August 21, 2021, 01:28:16 pm »
Its the cheapest fan B&Q had on their shelf so it not complete chinese rubbish.

.. no, that means it absolutely is complete rubbish. B&Q have a long history of products which catch fire.
 

Offline MajorbobTopic starter

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Re: UK toilet extractor fan
« Reply #37 on: August 21, 2021, 11:33:34 pm »
It's a manrose vxf100s, so I don't believe it's insta-fire.
 

Offline floobydust

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Re: UK toilet extractor fan
« Reply #38 on: September 05, 2021, 06:21:11 pm »
I forgot to follow up.
Manrose are a UK manufacturer "All fans are double insulated, manufactured to comply with EN60335-2-80:1997 and are CE marked"

That's an (older) safety standard, for ceiling fans, desktop fans, worried about electric shock, kids sticking their fingers in the blades etc. and apparently it has thermal tests/locked rotor heating so if they actually are certified product, it's not off the junk.
 

Offline Monkeh

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Re: UK toilet extractor fan
« Reply #39 on: September 05, 2021, 06:29:28 pm »
I forgot to follow up.
Manrose are a UK manufacturer "All fans are double insulated, manufactured to comply with EN60335-2-80:1997 and are CE marked"

That's an (older) safety standard, for ceiling fans, desktop fans, worried about electric shock, kids sticking their fingers in the blades etc. and apparently it has thermal tests/locked rotor heating so if they actually are certified product, it's not off the junk.

It's an ancient, extremely low end model they won't even acknowledge exists any more, and to this day they sell products which don't take into account the wiring systems they're to be conneced to. It's junk. Perhaps not a fire (yet), but crap nonetheless.
 

Offline floobydust

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Re: UK toilet extractor fan
« Reply #40 on: September 05, 2021, 06:47:35 pm »
What is it that makes it junk? UK seems to be possible to dodge the safety standards with "designed to" or just not mention any standards, or hype the one environmental standard it achieves. "manufactured to comply" does not mean it actually was tested/evaluated and does comply.
It's probably a chinese fan motor and just locally assembled to claim "made in the UK". I see many importers of chinese junk reselling it locally sans safety approvals. What a way to make money- peddling unsafe crap.

The 3A fuse is not enough to prevent a fan or circuit board fire, I'm not sure what it's good for really. Protecting the wiring?
 

Online Gyro

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Re: UK toilet extractor fan
« Reply #41 on: September 05, 2021, 07:37:55 pm »
The 3A fuse is not enough to prevent a fan or circuit board fire, I'm not sure what it's good for really. Protecting the wiring?

Yes, that's my take on it, It's probably thin stranded flex (I've never had any luck getting solid T&E in there!), which may not be fully captured. Widespread, non-industrial, availability of ferrules seems to be a recent thing.
Best Regards, Chris
 


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