Wiring up an extractor fan

[bernardgreen]

Class 2 appliances do not have "exposed-conductive-parts" in our electrical meaning.

Sadly faults do not have any awareness of "our electrical meaning" and exposed to touch metal can in fault ( or mis-use ) situations become in contact with Live parts.

 

[winston1]

Maybe because in the UK we have higher safety standards, We in the UK prefer the fuse / MCB to remove power before the cable gets warm due to a faulty appliance / wiring while those in the EU are happy for the cable to get hot before the over current protection removes power.

The only reason we have cartridge fuses in plugs/FCUs is because we use 32a MCBs on our rings.

 

[winston1]

Having seen a table lamp cable almost melt ( table damaged ) before the protective device operated I feel the ability to put a 3 amp fuse in the circuit is a necessary "extra" safety method when the socket is protected by a 16 or 6 amp device in the consumer unit.

Must have had the wrong cable on it then.

 

[bernardgreen]

Must have had the wrong cable on it then.

It was as sold in the shop. There was some mis-use in that the lamp fitted was a higher wattage then the one supplied with the lamp.

 

[winston1]

It was as sold in the shop.

That does not mean it didn't have the wrong cable on it.

 

[JohnW2]

The manufacturer states ""This is a Class Two Appliance and MUST NOT be Earthed""

We've been through this many times before, and I do personally disagree with the "MUST NOT" wording that we very commonly see. As you go on to say, I think that the only reason for not doing it (assuming there is some exposed metal that could be earthed!) is ...

So what harm can come from earthing the appliance's exposed to touch metal work ? I am aware that if the person was holding a live bit of metal in one hand they could safely touch an un-earthed appliance with the other hand, but if that appliance's exposed to touch metal was earthed then they could received a severe, possibly fatal shock.

However, that's nothing to do with the safety of the appliance, per se, nor even anything to do with the fact that the object in question is anything to do with electricity - to address the argument you cite, one might just as well (in fact, probably 'more reasonably' in many cases) say that "this sink (or metal shelving, or metal window/door frame, or coat hook or ......) MUST NOT be earthed".

I think it might be like JohnW2 who uses the smallest possible - because you can. It is more likely just what they write.

Not only "because I can" but, rather, "because I can, and whilst I can see no way in which it can do any harm (other than wasting energy in heating the fuse slightly more!), and given that the cost is the same, it might conceivably offer a benefit in some situations".

Kind Regards, John

 

[Keitai]

Spoke to an electrician at b and q and he said it's fine to have 3 amp fuse in plug. The double polr switch fused spur outlet thing is wired wrongly in my kitchen as each appliance should have an individual one for it and no plug socket. Makes no difference to just have a plug . The plug just doesn't look as smart to the eye that's all.

 

[SFK]

Keitai
"The plug just doesn't look as smart to the eye that's all."

If not wanting to use a plug for cosmetic reasons,
then replace the socket that is above the extractor fan with this, as this has a cable flex out hole on it bottom edge. Your cable is then wired though the hole in the bottom edge.
https://www.screwfix.com/p/mk-logic...ts/13479#product_additional_details_container

 

[ericmark]

Yes just use 13A plug and 3A fuse, forget all the rest, you don't need to know.

 

[JohnW2]

Yes just use 13A plug and 3A fuse, forget all the rest, you don't need to know.

Given that there are some here who feel that one has to strictly stick to (or, at least, advise people to strictly stick to) the letter of the manufacturer's instructions, do you believe that use of a plug/socket would satisfy "...must be connected directly to the mains..."?

Kind Regards, John

 

[EFLImpudence]

Is there a reason the manufacturer might believe that that would make any difference?

 

[JohnW2]

Is there a reason the manufacturer might believe that that would make any difference?

Not that I can think of. However, it has been suggested (not by you or myself) that we should only advise DIYers on the basis of 'the letter of the MIs' (whatever those MIs might say).

Kind Regards, John

 

[winston1]

Spoke to an electrician at b and q and he said it's fine to have 3 amp fuse in plug. The double polr switch fused spur outlet thing is wired wrongly in my kitchen as each appliance should have an individual one for it and no plug socket. Makes no difference to just have a plug . The plug just doesn't look as smart to the eye that's all.

Didn't know B&Q had electricians. He is wrong. The double pole FCU can supply as many appliances as you want up to 13 amps. Each appliance does not need one at all just a plug.
You may not think a plug does not look smart. You may change your mind when you come to replace, say your toaster, and have to pay an electrician to disconnect it and wire in the new one.

 

[winston1]

However, it has been suggested (not by you or myself) that we should only advise DIYers on the basis of 'the letter of the MIs' (whatever those MIs might say).

Kind Regards, John

And if the manufacturers instructions are blatantly wrong and dangerous?

 

[JohnW2]

And if the manufacturers instructions are blatantly wrong and dangerous?

You would have to ask the person who said that we should only advise DIYers to follow manufacturer's instructions to the letter (as you imply, I don't think that is necessarily always sensible).