3 kW heater switch getting hot!

[JohnW2]

.... the element would burn out and a loose end could drop on to a lower part of the element thus putting a somewhat shorter length of element across the mains. Overload.

Yes, that's the argument that dissenters always produce. It's theoretically not impossible, but can you really say that it is "likely"? How many times have you seen, or heard, of it happening?

Some types of loads must have been in the minds of the authors of BS7671 when they went to the trouble of writing a regulation which specifically (and only) relates to loads "not likely" to result in an overload current in the cable supplying them. What sort of loads do you think they had in mind??

Kind Regards, John

 

[JohnW2]

Why would the element burn out if a fan failed?

In the absence of a properly functioning thermal cut-out device, that's precisely what happens if the fan of a fan heater fails. However, we're not talking about a fan heater, so the point is somewhat irrelevant!

Kind Regards, John

 

[Dozy Danum]

Hello, OP here, as John and others have said, it isn't a fan heater it's a Stiebel Eltron 3 kW radiant wall heater, (no fan). As I've said previously I have now fitted the 20 amp fuseless switch. Have I, or have I not done the right thing?

 

[JohnW2]

Hello, OP here, as John and others have said, it isn't a fan heater it's a Stiebel Eltron 3 kW radiant wall heater, (no fan). As I've said previously I have now fitted the 20 amp fuseless switch. Have I, or have I not done the right thing?

As far as EFLI, myself and undoubtedly many others are concerned, you have done a perfectly reasonable (probably the best) thing, which we also regard as compliant with the Wiring Regulations. There is obviously at least one person who disagrees, but you have to decide what notice to take of him!

Kind Regards, John

 

[EFLImpudence]

This from the only instructions I can find.

Albeit it is American and they only list heaters from 0.5 to 2.4kW.
http://www.stiebel-eltron-usa.com/sites/default/files/pdf/install-cns-e.pdf

Note the third:

British site:
http://www.ehsshop.co.uk/panel_heat...el_heater_with_24hr_timer_cns300ut_P1303.html

 

[stillp]

Are you sure that's American? They managed to spell 'gauge' correctly!

 

[EFLImpudence]

Well, I couldn't find any .co.uk ones.

 

[Dozy Danum]

Yeah, EFL, I've now got a feeling it didn't come with a plug because when I was fitting the new switch yesterday I noticed the solid brass ends on the wires in the cable. Therefore if there had have been a plug it would have been a modern one that couldn't have been pulled apart. Also now I've looked at the website and it says ideal for bathrooms and it shows a picture with the cable going into a wall, so it probably does have to be hardwired.
Winston, I think I understand what you're saying about the cable being rated 20 amp but I can't find find out anywhere if it is. All I can find is the heater is rated 13 amp.

 

[EFLImpudence]

Winston, I think I understand what you're saying about the cable being rated 20 amp ... All I can find is the heater is rated 13 amp.

It doesn't have to be because, as you say, the heater is 13A and won't cause an overload - draw more than that.

The cable just has to be rated to cope with fault current and trip the MCB without melting, which it will.

 

[Dozy Danum]

Thanks again EFL. I think somewhere on the download instructions in says wire into a junction box so it must be ok to do what I've done.
New switch doesn't get hot by the way!

 

[EFLImpudence]

 

[333rocky333]

The 3 heaters I brought last week all had screw on plugs, not moulded ones, we wall mounted them and connected to existing Fcus, though they were only 2kw max

Do you recommend a fuse for immersion heaters?

Drifting off topic slightly, recently ive had about 6 FCUs burnt out for immersions, in each case load measured 12. something amps and similar to the OP the heat was concentrated round the fuse holder.
They were a mix of, some 16a and some 20a radials , I was under the impression I could replace with 20 amp switches, I think that was quite common back in the day for Immersions, storage heaters and most, electrical element, fixed appliances.

Though similar to Winstons thoughts, I was often told I should change The 1.5 butyl to 2.5, were they right telling me that, I dont recall ever seeing a 2.5 butyl to an immersion, or a small less than 3kw storage heater

 

[EFLImpudence]

Drifting off topic slightly, recently ive had about 6 FCUs burnt out for immersions, in each case load measured 12. something amps and similar to the OP the heat was concentrated round the fuse holder.

Yes, it must be something to do with poor manufacture.
I have known an immersion being run on a socket, plug with plug-in timer "for ever" with no ill effects and yet, as you say, others ???

They were a mix of, some 16a and some 20a radials , I was under the impression I could replace with 20 amp switches,
I think that was quite common back in the day for Immersions, storage heaters and most, electrical element, fixed appliances.

You can - that's what should have been fitted in the first place.

Though similar to Winstons thoughts, I was often told I should change The 1.5 butyl to 2.5, were they right telling me that,

Not really, if the cable can handle the 13A - but

I dont recall ever seeing a 2.5 butyl to an immersion, or a small less than 3kw storage heater

I thought they all were on 2.5, that's what the sheds sell as 'immersion cable'.