Omission of overload protection for resistive heating elements.

[EFLImpudence]

Ah, I am due a new toaster. When I get one I shall connect a quarter of the old filament to the supply and see what happens.

Firstly by just placing the filament in a connector block and then with the screw tightened.

 

[JohnW2]

Ah, I am due a new toaster. When I get one I shall connect a quarter of the old filament to the supply and see what happens. .... Firstly by just placing the filament in a connector block and then with the screw tightened.

Well, we know what will happen, current-wise - at least 'with the screw tightened'.

I suppose what you are implying is that you think the (bit of) element would 'burn out' (act as a 'fuse') fairly quickly if it were carrying around 4 times it's normal running current - and you may well be right.

However, I'm not sure that, per se, would satisfy those obsessed with the reg, since, unlike some other regs, this one says nothing about "for long periods", so it could be argued that overload protection is required if there is "likely" to be an overload current of any duration (even if very short). However, even with the toaster I still don't believe it is "likely" that there will ever be an overload current (of any duration) - although, having said that, I don't think I would attempt to invoke the "overload protection not required" idea in the case of a toaster (or whatever) with an 'open' element.

Kind Regards, John

 

[winston1]

There are 2 threads here, I'm there are others, where it is stated that individual overload protection is not required. Yet in the recent thread SUNRAY was convinced otherwise. I can't help but think he was deliberately having a go at me.

https://www.diynot.com/diy/threads/induction-hobs.558899/
https://www.diynot.com/diy/threads/oven-and-hobs-again.172175/

 

[SUNRAY]

Rule or no rule, I haven't seen such an animal for decades. Toasters and some small standalone 'grills' etc. (and fan heaters etc.) are a different matter, but we're not discussing them

Kind Regards, John

Maybe, but the subject is a small domestic oven and other similar domestic appliances.

I agree the reason for this thread is based on the previous threads Using pre installed cooker circuit for 13amp or 16amp oven.

I accept I have more experience with commercial equipment than domestic machines (despite finding I'm incorrectly on check-a-trade under 'domestic white goods'). However the title of the current thread is: 'Omission of overload protection for resistive heating elements' so all such are IMO fair game for discussion but I'll happily restrict my replies to any nominated topic.

Earlier I phoned a colleague who does do domestic white goods and he advises one of the German manufacturers of 'AGA' style electric cookers for several makes were the last to standardise on enclosed elements' in the last couple of years' and older cookers exposed elements are now repaired with an enclosed element and an adapter bracket. That said the old part number was the same as some of the Creda tumble driers so it is still available as such but not specified for the ovens anymore.

My gripe is the undersize cable installed by ignorant know-it-alls which again is something I've had the task of putting right on far too many ocassions, especially in the mobile catering industry.
One of MY 'old chestnuts':

As it happens this was the widow maker lead to be connected to the catering trailer, but that's a different thread title.

 

[SUNRAY]

There are 2 threads here, I'm there are others, where it is stated that individual overload protection is not required. Yet in the recent thread SUNRAY was convinced otherwise. I can't help but think he was deliberately having a go at me.

https://www.diynot.com/diy/threads/induction-hobs.558899/
https://www.diynot.com/diy/threads/oven-and-hobs-again.172175/

You are really scraping the barrel winny, neither of those have any relevance to anything I've posted. In other words more of your lies.

If you wish to continue this line of discussion, I'll happily do so but not in this thread as it would be a shame that your errors close another persons thread again.

 

[winston1]

I never lie. Both that threads are about putting a separate oven and hob on a 32a and in one case a 40a supply. In neither case was it said 2 separate 16a supplies was required.

 

[SUNRAY]

I never lie. Both that threads are about putting a separate oven and hob on a 32a and in one case a 40a supply. In neither case was it said 2 separate 16a supplies was required.

As I posted I will happily continue this line of discussion but only if YOU start another thread for it. I don't want to be party to you spoiling another persons thread again.

 

[JohnW2]

There are 2 threads here, I'm there are others, where it is stated that individual overload protection is not required.

What is written in threads is irrelevant. There's no argument about what the regs actually say, and say very clearly, namely (with my emboldening) ..

433.3 Omission of devices for protection against overload ....
433.3.1 General A device for protection against overload need not be provided:
.... (ii) for a conductor which, because of the characteristics of the load or the supply, is not likely to carry overload current, provided that the conductor is protected against fault current in accordance with the requirements
of Section 434

The only scope for discussion is therefore whether or not particular loads (like an oven element) are "likely to carry overload current" - and opinions about that appear to vary

 

[SUNRAY]

Ah, I am due a new toaster. When I get one I shall connect a quarter of the old filament to the supply and see what happens.

Firstly by just placing the filament in a connector block and then with the screw tightened.

I know from experience the element is very likely to be far too brittle to do much with. However bearing in mind a toaster element in nomal use is running extremely close to its melting temperature it won't need much more current before it fails. I recall one particular model having a problem with the jerk of the release mechanism breaking the fragile red hot element, just like a lamp bulb does when hot.

 

[SUNRAY]

What is written in threads is irrelevant. There's no argument about what the regs actually say, and say very clearly, namely (with my emboldening) ..
The only scope for discussion is therefore whether or not particular loads (like an oven element) are "likely to carry overload current" - and opinions about that appear to vary

So how far do we take these exemptions?
Would we be happy with a 3KW oven wired onto a 300A supply?
If so would we be just as happy if the flex was 100m long suitably sized for length of course but my gut feeling is 4mm².

 

[JohnW2]

So how far do we take these exemptions? Would we be happy with a 3KW oven wired onto a 300A supply?

The implication of the regulation is that such would be 'permitted' (indeed, no overload protection at all, if fault protection were somehow provided) provided that it was not considered "likely" that the load would result in an overload current.

Are you suggesting that 433.3.1(ii) should not exist at all? If so, then you are not really complaining to the right people!

Kind Regards, John

 

[SUNRAY]

The implication of the regulation is that such would be 'permitted' (indeed, no overload protection at all, if fault protection were somehow provided) provided that it was not considered "likely" that the load would result in an overload current.

Are you suggesting that 433.3.1(ii) should not exist at all? If so, then you are not really complaining to the right people!

Kind Regards, John

Personally I don't like it at all, I struggle with unprotected cables, even some of the downstream protection frequently leaves a lot to be desired. But hey ho perhaps I have better standards than others. Actually when I see some of the total excretia done by some, I know I do have better standards than some.

 

[bernardgreen]

Actually when I see some of the total excretia done by some, I know I do have better standards than some.

I came to the conclusion years ago that regulations are a minimum standard below which no one should sink. Working to a better standard should not be prohibited and anyone who does work to a better standard is ( in my opinion ) far better than anyone whose work is just above the standard set by the regulations.

 

[SUNRAY]

Personally I don't like it at all, I struggle with unprotected cables, even some of the downstream protection frequently leaves a lot to be desired. But hey ho perhaps I have better standards than others. Actually when I see some of the total excretia done by some, I know I do have better standards than some.

This isn't to say I am completely opposed to downstream OCDs, in control panels for example it's quite common to have live terminals or busbars rated at tens/hundreds/thousands amps and wires as thin as 2.5mm² linking to OCDs, of course the wiring containment is usually very closely controlled in panels which is very different to a flex bundled behind a hot oven or a cable chased into walls for a room heater/thermostats etc.

 

[JohnW2]

Personally I don't like it at all, I struggle with unprotected cables, even some of the downstream protection frequently leaves a lot to be desired. But hey ho perhaps I have better standards than others.

That's a perfectly reasonable viewpoint, with which I can sympathise.

However, if your view is that omission of overload protection should never be allowed, would it not have been much simpler to just say that, rather than engage in discussions/arguments about whether it should be allowed in relation to one particular type of load?

Kind Regards, John