Socket with 1mmT&E and 10A MCB?

[SJD]

I have a customer who had a boiler removed from the kitchen (re-sited) and happens to have a socket-sized apperture in the tiles (originally switch for supply to boiler) that he would like to use as a socket for a microwave nearby. The cable from the socket goes directly to a moderately recent CU about 3m away, but is unconnected (it is above a 16A MCB). The snag is the cable is 1mm T&E, so it too small (mostly reference method A, max current 11.5A) to protect with a 16A MCB. It is not an option to replace the cable.

Question: would it be considered acceptable to fit a smaller MCB, for example a 10A MCB, and perhaps put a label on the socket saying something like "10A Max"? It won't stop someone plugging in a 3kW kettle instead, which might not even trip the breaker in the time it takes to boil, so I remain a bit sceptical about doing this.

 

[Paul.M]

No problems putting it on a 10A mcb and lable the socket as youve said.

 

[dagrat]

Definately not SJD, virtually guaranteed that something heavy would be connected at some stage, particularly as its a kitchen. An alternative would be to use a round pin socket and plug which are rated to 5amps, but again is not the preferred solution.

 

[kingeri]

It's not ideal but sometimes you have to work with what you have. At the end of the day the cable will be protected, so no worries there. Depending on the power draw of the microwave, you might even be able to use a 6a breaker. Socket could be labelled 'Microwave Only - Max 6a/10a'.

 

[kingeri]

Definately not SJD, virtually guaranteed that something heavy would be connected at some stage, particularly as its a kitchen. An alternative would be to use a round pin socket and plug which are rated to 5amps, but again is not the preferred solution.

If the work you do is compliant with the regs, you cannot be expected to plan for every eventuality that'might' occur in the future. I agree it's not the first choice, but if it's all done within the regs, who can argue?

 

[Deleted member 26818]

I don't see that there is a problem with what is proposed.
As long as Ib ≤ In ≤ Iz is met, there should be no problem.

 

[Strima]

That would be an ideal candidate for a USB style socket marked up for phone charging use only...

As has been said, you can't cater for every eventuality.

 

[kingeri]

That would be an ideal candidate for a USB style socket marked up for phone charging use only...

As has been said, you can't cater for every eventuality.

Good idea!

 

[Strima]

Good idea!

Make the most if it, I don't have many moments... :lol:

 

[Richard Burns]

The regs do state that the minimum csa that is permitted for power circuits is 1.5mm2 so you would fall afoul of that, however the protection as specified would be adequate.

 

[Knobhead]

I would go for a 5A switched socket and 6A MCB. But thats just my veiw of it.

If you're customer has MK outlets in the kitchen you can even get them to match.

 

[somersetsparks]

I would just put a single socket on it 10A mcb, cable is protected, If they do plug anything in it will be a max of 13A. Are you sure it is method A for the cable? (remember cables capped in a masonary wall are C, cables run through floor voids are B as are cables in oval conduit) Method A is embeded in a thermally insulated wall? not doubting you but you wouldn't believe how many people put A just becuase cables are flush!

If it was B that would allow 13A, so a 10A B type MCB carrying 13A would trip in.... a long time maybe!

 

[SJD]

Thanks guys for the replies. Consensus generally seems to be it would be OK, perhaps using a 6A MCB if that is sufficient for the intended use (I will have to check). Though I did manage to find reg 524.1 and table 52.3 (I'd forgotten about that table) as Richard Burns alluded to, so I'd need to note that as a deviation on the certificate.

 

[SJD]

I would just put a single socket on it 10A mcb, cable is protected, If they do plug anything in it will be a max of 13A. Are you sure it is method A for the cable? (remember cables capped in a masonary wall are C, cables run through floor voids are B as are cables in oval conduit) Method A is embeded in a thermally insulated wall? not doubting you but you wouldn't believe how many people put A just becuase cables are flush!

If it was B that would allow 13A, so a 10A B type MCB carrying 13A would trip in.... a long time maybe!

Actually the cable is a mixture of methods, some is in the floor void, some in capped masonary, a small bit in a partition wall with some filling (I have to admit I'm not sure how insulating). Quite possibly it would be sufficient to assume method B.

 

[somersetsparks]

Actually the cable is a mixture of methods, some is in the floor void, some in capped masonary, a small bit in a partition wall with some filling (I have to admin I'm not sure how insulating). Quite possibly it would be sufficient to assume method B.

Well if you can't see it then I supposemn you would have to assume it could be method A? I would go with 10A MCB and single socket