Isolation switches for kitchen island

[JohnW2]

Are isolators designed to break the current while a cooker is at full load?

I must say that I was brought up to believe that 'an isolator' did not have to be capable of breaking a full load and, for that reason, a functional switch' (which obvioulsy would be able to break a full load) should always be operated before one operated an 'isolator' on the circuit. On that basis, 'isolators' could obviously not be used as emergency (or functional) switches.

That terminolgy seems to have changed (or, at least, is commonly being used differently). In the present context, maybe the simplest thing to do is to forget about the word 'isolator', and merely talk about a 'switch' (which, once operated, also achieves the required features of 'isolation'!).

Kind Regards, John

 

[JohnW2]

In that case (if not for emergency use) the OP can hide them any where he likes.

Indeed - and I would remind you that it was you, not the OP (nor I, nor anyone else) who brought 'emergency switching' into this discussion.

Kind Regards, John

 

[EFLImpudence]

With two separate supply sources, the OP would presumably need at least two 'emergency isolators'

He is proposing three which I think could lead to confusion.

or are you suggesting that they should be mechanically linked in some way, to avoid that danger?

I wasn't . I think they should, unless impossible, be on the same circuit.


If the 'switch' is not for emergency 'switching' then, as I said, it can be positioned anywhere.

Table 53.4 - cooker control unit switch BS4177.
Isolation, yes(3)
Emergency switching (2), yes
Functional switching, yes

(2) see 537.4.2.5 - shall be readily accessible
(3) suitable for on load

In that case (if not for emergency use) the OP can hide them any where he likes.

Indeed - and I would remind you that it was you, not the OP (nor I, nor anyone else) who brought 'emergency switching' into this discussion.

But that is their purpose when used.
I am sure the OP hasn't asked because he wants them purely for their aesthetically pleasing appearance - especially three in a row.

 

[JohnW2]

With two separate supply sources, the OP would presumably need at least two 'emergency isolators'

He is proposing three which I think could lead to confusion.

Fair enough - and I indicated that, with the supply arrangements proposed, he would have to have at least two.

or are you suggesting that they should be mechanically linked in some way, to avoid that danger?

I wasn't . I think they should, unless impossible, be on the same circuit.

Would you normally suggest that someone should run a combi-microwave off a cooker circuit (as well as the oven and hob) - I don't think I've ever seen that done. What sort of cable CSA and OPD would you envisage would be necessary?

If the 'switch' is not for emergency 'switching' then, as I said, it can be positioned anywhere.

Indeed, we are agreed on that.

Kind Regards, John

 

[EFLImpudence]

With two separate supply sources, the OP would presumably need at least two 'emergency isolators'

He is proposing three which I think could lead to confusion.

Fair enough - and I indicated that, with the supply arrangements proposed, he would have to have at least two.

You did.
However the OP wrote -
"The ability to isolate each appliance separately - ok perhaps overkill!"
and
"note that I did consider putting all three appliances on the one 6mm cable. With diversity this would have been just within cable spec with a sensible choice of ovens and hob.

or are you suggesting that they should be mechanically linked in some way, to avoid that danger?

I wasn't . I think they should, unless impossible, be on the same circuit.

Would you normally suggest that someone should run a combi-microwave off a cooker circuit (as well as the oven and hob) - I don't think I've ever seen that done.

I don't understand. Is it not a built-in cooking appliance.?

What sort of cable CSA and OPD would you envisage would be necessary?

You do not need me to calculate such things for you.
Why even ask?

 

[JohnW2]

Would you normally suggest that someone should run a combi-microwave off a cooker circuit (as well as the oven and hob) - I don't think I've ever seen that done.

I don't understand. Is it not a built-in cooking appliance.?

I don't think we've actually been told that it is 'built-in', but I agree that it probably is. It's the concept of having three cooking appliances on one circuit which I was suggesting would be unusual.

What sort of cable CSA and OPD would you envisage would be necessary?

You do not need me to calculate such things for you. Why even ask?

It was really an essentially rhetorical question - i.e. I was implying that having three cooking appliances on one circuit might well need a fatter cable and larger OPD than is common for a cooker circuit. A lot depends upon how one deals with diversity. I strongly suspect that you will not share my view, but I personally would be a little hesitant to apply diversity across all three appliances 'lumped together' - but would be more inclined to treat the combi-microwave separately. I'd be interested to hear your view on that.

Kind Regards, John

 

[EFLImpudence]

What sort of cable CSA and OPD would you envisage would be necessary?

You do not need me to calculate such things for you. Why even ask?

It was really an essentially rhetorical question - i.e. I was implying that having three cooking appliances on one circuit might well need a fatter cable and larger OPD than is common for a cooker circuit. A lot depends upon how one deals with diversity. I strongly suspect that you will not share my view, but I personally would be a little hesitant to apply diversity across all three appliances 'lumped together' - but would be more inclined to treat the combi-microwave separately. I'd be interested to hear your view on that.

I don't see the difference between two (separate) ovens and hob, a double oven and hob or a range.
The larger the appliance(s) the more favourable is diversity - very little on a small appliance.
Assuming(?) the 6mm² cable is installed method C then it is not going to be overloaded with a 32A OPD or a 40A - or even a 45A.

We do not know the ratings of the appliances in this case but the OP stated he could just get away with it.
I suspect there is more leeway than he thinks.
Without an integral socket (in the switch) 32A with diversity allows 19kW @ 230V, (20kW @ 240 as per manufacturer).
So, if you want to fit a 40A or 45A OPD there is plenty of spare capacity.

You are just asking me to quote and calculate as per the regulations.
That you disagree or have reservations doesn't really make a difference.

 

[JohnW2]

I strongly suspect that you will not share my view, but I personally would be a little hesitant to apply diversity across all three appliances 'lumped together' - but would be more inclined to treat the combi-microwave separately. I'd be interested to hear your view on that.

You are just asking me to quote and calculate as per the regulations. That you disagree or have reservations doesn't really make a difference.

I have responded (at length!) to this in a spin-off thread ( here ). Please continue any discussion about the concept of diversity in that new thread, not this one.

Kind Regards, John

 

[STEVEROG]

I've just caught up with this thread....I can't help feeling like I've opened up a big can of worms!

 

[EFLImpudence]

Don't worry, some of us can make cans of worms out of anything.

 

[JohnW2]

Don't worry, some of us can make cans of worms out of anything.

I wouldn't go quite that far ... even I might have a problem in making a can of worms out of some things

Kind Regards, John

 

[JohnW2]

I've just caught up with this thread....I can't help feeling like I've opened up a big can of worms!

Apologies - as is often the case, I cannot deny responsibility!

As you may have worked out, the bottom line of the 'banter' is that you could have oven, hob and combi-microwave all on one circuit (32A or above, with your proposed cable), with one isolator (or 'emergency switch', or however you wish to view it) if you wanted, but I personally feel that there are practical advantages (some of which you have mentioned yourself) for having the microwave on a separate circuit, and for having separate 'isolators' (or whatever!) for each of the cooking appliances.

Apologies again for having muddied the water a bit!

Kind Regards, John