Cooker / Induction Hob isolation

[Rad1o]

We are having a new kitchen installed where we are going from gas and electric to all electric.
I have searched the internet for information on the legal and COMPULSORY necessity for an isolation switch for cooker and hob.

We have 2 separate MCBs for either device in the fuse board where they can be switched individually. The cooker has an existing one with 32A and the hob has a newly wired 32A circuit.

I cannot find anything in the regs to state a compulsory requirement for a switch in the kitchen. Often it only says that it is a "good idea" and "good practice" and should be considered for convenience.
In edition 17 the requirement for an isolator and Positioning of emergency switching for fixed or stationary appliances
has been dropped completely. It only says that every installation requires a means of isolation which is my MCB.

Other forums state and confirm what I found and seem to interpret.

Apart from this my sister lives in Germany. Their kitchen and those of friends that I have visited do not have these dead ugly cooker switches. We have been to Switzerland on holiday and rented flats and the only form of isolation they use is the fuseboard. These cooker switches seem an archaic relic.

Is there anything in english law that should convince me to put one of these ugly switches back on the wall. Can I have a link for reference please.

 

[JohnW2]

Is there anything in english law that should convince me to put one of these ugly switches back on the wall. Can I have a link for reference please.

The Wiring Regulations (currently BS7671:2008 Amd 1, aka '17th edition') are not actually law, and hence not mandatory. The only relevant law is Part P of the Building Regulations, but that is so vague (basically just a statement that things should be done safely) that most people rely on the Wiring Regs as 'evidence' that they have complied with the law.

Anyway, as you say, the regulations only require that there should be a method of isolation - which, as you also say, could be in the consumer unit. How sensible it is not to have a 'local' means of isolation probably depends mainly on how far it is from the cooker to the CU.

There is another issue. The Wiring Regulations do require compliance with any instructions issued by the cooker manufacturer. Hence, if the manufacturer says that you have to have one of these 'ugly switches', then the Wiring Regs would require you to comply with that instruction.

Hope that helps.

Kind Regards, John

 

[EFLImpudence]

What do you mean, ugly -

 

[ericmark]

In Europe they do use double pole MCB's but in the UK our consumer units only support the use of single pole MCB's which with a TN system can be considered to isolate, but not with a TT system.

 

[JohnW2]

In Europe they do use double pole MCB's but in the UK our consumer units only support the use of single pole MCB's which with a TN system can be considered to isolate, but not with a TT system.

True, but any CU/DB/Fuse board will provide a 'means of (double pole) isolation' (for a cooker or anything else) in the form of a main switch or DP RCD incomer.

Also, as a matter of detail, AFAIUI many UK CUs do support DP MCBs/RCBOs - although you will very really see them used (even if you can find them).

Kind Regards, John

 

[securespark]

As has been said, TECHNICALLY, you COULD use the main switch to isolate your faulty / blazing cooker/ hob, but if the CU is time-consuming to get to, this is not a sensible move. Your art gallery will not look good covered in soot.

But this would mean isolating the whole house. Hardly convenient.

If your appliance instructions demand a DP isolation switch with a minimum clearance between all poles of 3mm (which IME they do), then by omitting such a switch you are wiring contrary to the regulations. As others have said previously, wiring to the regs is one way to show compliance with Part P of the BR, so.....

 

[EFLImpudence]

On the other hand -

 

[JohnW2]

As has been said, TECHNICALLY, you COULD use the main switch to isolate your faulty / blazing cooker/ hob, but if the CU is time-consuming to get to, this is not a sensible move. Your art gallery will not look good covered in soot. But this would mean isolating the whole house. Hardly convenient.

The reality, of course, is that (as the OP suggested) in such an emergency situation, a (single-pole) MCB would usually give perfectly adequate 'isolation' (certainly adequate to render it temporarily 'safe'), without affecting the rest of the house. Indeed, with TN earthing systems, even the regs do not require double-pole isolation and, in the case of TT, I think you would really have to try very hard indeed to come up with some (incredibly unlikely) scenario whereby SP isolation was not adequate as an 'emergency' measure.

As for the desirability of a 'local isolator' for a cooker, as I've already said, that desirability will depend upon the proximity of the CU. Quite frankly, if a cooker were on fire, or if I had reason to believe that, say, the casing had become 'live', I would be more inclined to walk a few paces to a CU (since that's all it would be in most homes) than to brave the vicinity of the 'dangerous' cooker to get at and operate a local isolator ... so I really do think there are two sides to all this.

If your appliance instructions demand a DP isolation switch with a minimum clearance between all poles of 3mm ...

Yes, I've already mentioned that. However, if all it says is that there must be a DP isolation switch which provides 3mm contact separation (without sayiing where that should be located), it could still be satisfied by a CU main switch or (DP) RCD. The fact that the MIs require such an isolator to be present can't force anyone to use it - so one could still (as above) use an MCB to isolate in an emergency (thereby sparing the rest of the house) if one so wished!

Kind Regards, John

 

[Rad1o]

As has been said, TECHNICALLY, you COULD use the main switch to isolate your faulty / blazing cooker/ hob, but if the CU is time-consuming to get to, this is not a sensible move. Your art gallery will not look good covered in soot.

But this would mean isolating the whole house. Hardly convenient.

If your appliance instructions demand a DP isolation switch with a minimum clearance between all poles of 3mm (which IME they do), then by omitting such a switch you are wiring contrary to the regulations. As others have said previously, wiring to the regs is one way to show compliance with Part P of the BR, so.....

In the unforeseen event of a kitchen fire - electric or other - cutting the power will not lessen the flame or even stop it. If I have not completely lost it in such an event I would just run for the phone and out.
Our fuse board is in the next room - 4 more steps - but that should have tripped if it was shorting and the cause for the fire.
I will check with the cookeer manufacturer.

 

[DetlefSchmitz]

In the unforeseen event of a kitchen fire - electric or other - cutting the power will not lessen the flame or even stop it. If I have not completely lost it in such an event I would just run for the phone and out.
Our fuse board is in the next room - 4 more steps - but that should have tripped if it was shorting and the cause for the fire.
I will check with the cookeer manufacturer.

The fire will not be caused by an electrical fault so nothing will have tripped.

I have had a hob fire. It was caused by fat catching fire. The solution was

a) flip the isolator off to remove the source of heat
b) dampen a towel and place over the pan to cut off the air.

This was completely successful. I know that if I had just left it and gone to a phone we would have lost the house.


Still it's up to you.

 

[JohnW2]

I have had a hob fire. It was caused by fat catching fire. The solution was ... a) flip the isolator off to remove the source of heat.

I assume that means that the isolator was sufficiently distant from the burning fat that you could get to it to 'flip it off' without endangering youself? Some of the 'chip pan fires'I've seen (fortunately only on TV!) are sufficiently ferocious that there's no way that I would attempt to operator a 'local isolator' if it were anywhere near the cooker!

As a matter of interest, how far was your CU from that cooker?

Kind Regards, John

 

[DetlefSchmitz]

I suppose about 1 m to the switch. The flames went straight upwards nearly reaching the ceiling. I was summoned by cries of 'help, help!'.

Our only problem was that the towel I used got slightly burn marked and was spoiled. (I think we probably got off lightly.)

 

[JohnW2]

I suppose about 1 m to the switch.

Just about enough in most situations, I suppose, although some are obviously a lot closer than that, and really not safe to get at if there is a good-going inferno on top of the hob! ... and you forgot to mention, roughly how far away was the CU?

Kind Regards, John

 

[DetlefSchmitz]

In those days it was in the garage, a long way away. House would have burnt down before we located the key.

In the current kitchen (new extension), probably 4 metres away. The isolation is more like 30cm from the hob, but I guess we now have the choice. At least in the day time. You wouldn't want to throw the main switch off on a fire at night time.

Actually the old switch ended up behind a small wine rack, and the new one has a row of bottles in front like balsamic vinegar etc. I guess we never learn.

 

[SimonH2]

There's always the option of putting the isolator out of site.

OK, it does partially defeat the option since you've have to toss a load of stuff out of the cupboard to get to the switch in a hurry - but you'd have your local isolator and hence comply with "expectations".