Radial circuit

[Block642]

Hi I have just moved into a house and have some concerns about the electrics.

I know a little bit about electrics (not enough to do it myself) so wanted to get it clear in my head what I am asking of an electrician!!

One of the MCBs on the consumer unit controls the sockets in the kitchen, one bedroom and utility room.

The MCB is 16amp. The cable from the the consumer unit is 4mm to the first socket in the kitchen and bedroom. After that it becomes 2.5mm. There are 4 double sockets in the kitchen, 3 in the bedroom and three in the utility.

When I have the washing machine on and the tumble drier it will sometimes trip the mcb.

First of all I want to know if this set up is safe? Secondly how can I stop the MCB tripping. A friend has suggested getting an electrician to swap the 16amp mcb for a 20amp. Would this help and is it safe with 2.5mm cable?

Thanks for your help.

 

[imroberts]

2.5mm cable is normally fine with a 20A MCB. If it runs through insulation though then it may be derated to lower than this.

The reason your MCB keeps tripping is most certainly due to the load of the washer and tumble dryer. Both are likely to use upto 13A so it's possible they may also trip a 20A MCB. It'll probably happen less frequently though

If it were me, with a kitchen and a utility room, I'd look to see if the electrician can make the circuit into a 32A ring.

 

[Block642]

Yeah thats what I thought, but it would mean a lot of mess and making good of ceilings/walls so if it could be solved using the existing circuit I would rather do that.

 

[echoes]

It may be possible to use a 20A MCB, but that still leaves the circuit ill-designed for a kitchen + utility room with appliances.

If you don't want to convert the existing circuit to a 32A ring, which at face value would appear to be an efficient solution, could new circuit(s) be run to your high power appliances without disruption?

Or could the exitsting 2.5mm² cable be replaced with 4mm cable, which might allow 32A+

 

[Block642]

Hmm could the circuit be converted to a 32amp ring without replacing the 4mm cable, therefore creating a ring circuit on a 32amp MCB with some 4mm cable and some 2.5mm cable.

This may be possible with little disruption.

 

[Block642]

Just for your amusement my wife has now told me that she had TWO electric heaters on in the bedroom to warm it up before the baby went to bed! She didn't want to put the central heating on (bless her cotton socks)

Didn't think of telling me that when I was looking at the consumer unit scratching my head.

 

[EFLImpudence]

could the circuit be converted to a 32amp ring without replacing the 4mm cable, therefore creating a ring circuit on a 32amp MCB with some 4mm cable and some 2.5mm cable.

Yes, it's not the 4mm² that is the problem.