a radial, a ring, it's a kitchen thing!

[Ejaz]

hello peeps! Need some advice. I have two sockets coming off the ring main circuit in the kitchen. There is also what appears to be a 20amp radial circuit supplying a single socket for the washing machine.

I'm re-fitting the kitchen so i'm not sure whether i should extend the radial to supply the whole kitchen or only extend to supply a fridge/freezer and 2 double sockets. This would mean one side supplied by the ring main and the other side by the radial.

also going to fit a gas cooker. CU is the rewireable fuse type.

thanks in advance!

 

[pdcelec]

Call an electrician in and they will supply what is required. Alternatively learn the wiring regulations and the requirements of Part P.

 

[JohnD]

You can extend the 20A radial. However it will not be able to support more than two heavy load appliances (if that). Choose any two from: Oven, washing machine, tumble drier; dishwasher, electric heater.

Also, do not plug two of these into a double socket, or it will overheat. Put each on a single socket.

If you have any one of those appliance going through a heating cycle, and use the kettle and toaster at the same time, it may blow your fuse

It can be very handy to have a row of sockets on the radial for your small worktop appliances.

What size does the cable in the 20A circuit seem to be? Does it look the same size as the cable on the ring?

 

[joe-90]

Also, do not plug two of these into a double socket, or it will overheat. Put each on a single socket.

Can't say I've ever heard that before, John. A socket has a bus-system that is far heavier than the cable supplying it or fuse protecting it. Surely, only a damaged socket with bad contacts causing arcing would create such a problem. Double sockets would be banned if what you say is true. It isn't expected of the housholder to be aware of such matters, so safety would be permanently at risk.

 

[sm1thson]

Joe, its true double sockets are only rated for 13amps, thats 13amps shared between the two, so where you need two high power appliances side by side you should use a dualbox (to hold two singles). i guess the problem doesn't show its head as often as one might expect as most plug in high power appliances do not pull high power for long so time comes into play.

Ejaz, Im not full sure how your ring is set up, but i would consider using the radial for fridge freezer and have this none RCD protected, then use the ring for the rest of the kitchen sockets (RCD protected), this way if your on holiday and something trips the RCD elsewhere in the house your freezer stays on. -something to concider? but take note of what johnd and pdcelec have said -its true!

 

[Ejaz]

wow thanks for the quick response! yep the 20A radial is wired in 2.5T+E. So my initial thoughts are to run the cooker (runs off 13amp socket) and the fridge/freezer of the ring main with one double socket above counter.

Then run the washing machine and 3 additional double sockets of the 20A radial, does that sound reasonable?

Not sure about RCD for the fridge/freezer will have to think about that one.

I did have a brief read of the "Electricians Guide to Part P" it's the small green guide that was helpful, might get a copy.

Forgot about the cooker hood, i'll supply that off the ring main also.

 

[joe-90]

Joe, its true double sockets are only rated for 13amps, thats 13amps shared between the two, so where you need two high power appliances side by side you should use a dualbox (to hold two singles). i guess the problem doesn't show its head as often as one might expect as most plug in high power appliances do not pull high power for long so time comes into play.

Sorry for being thick, but I've just broken open an old socket and the brass bus inside seems to have at least 5 times the cross sectional area than the cable that would lead into it. So my question is:

Why does the much heavier brass bus heat up when the lighter wirel eading in does not? It's science that matters - not regs.

 

[JohnD]

There is a lab report somewhere, I couldn't find it, but someone will.

A single socket will get quite hot with a 3kW heater on it, I imagine the rate of heat loss when two such loads are in a single box is insufficient to cope with the gain.

The 13Amp socket system is (now) quite an old design, the expectation when it first came out was that someone might typically have (e.g.) an 3kW electric fire (was 12.5 Amps) on one side, and a 60W table lamp ( 0.25A) or some small other appliance such as a sewing machine (1A intermittent) on the other. Back in the late 1940's domestic users having a washing machine was rare, and a dishwasher or a tumble drier was unheard of. The Ring was designed to cope with a "reasonable" load at the time, including a couple of electric fires in a house used at one time, but not other large concurrent loads.

It is not unusual to find overheated double sockets that are brown, brittle and cracked, this most often occurs when a washing machine and a tumble drier are run at the same time for long periods, or if two electric heaters are used in a run-down rented flat with poor heating and insufficient sockets.

 

[joe-90]

Thanks for that John. I assumed it was just arcing that caused that problem, guess I was wrong huh? However, those regs need seriously looking at re current drawn and insulation etc. Why don't they just make everything 'heavier duty'? Cable sizes, switches, etc?

 

[davy_owen_88]

Thanks for that John. I assumed it was just arcing that caused that problem, guess I was wrong huh? However, those regs need seriously looking at re current drawn and insulation etc. Why don't they just make everything 'heavier duty'? Cable sizes, switches, etc?

Money? What householder would be happy paying double the material costs when they might not need it?

Its foolish to think that just because some people do overload their sockets/cables that everyone should have to have grossly oversized conductors. A well organised and fitted kitchen with a well designed and fitted electrical circuit will never have the problem JohnD pointed out.

 

[joe-90]

Thanks for that John. I assumed it was just arcing that caused that problem, guess I was wrong huh? However, those regs need seriously looking at re current drawn and insulation etc. Why don't they just make everything 'heavier duty'? Cable sizes, switches, etc?

Money? What householder would be happy paying double the material costs when they might not need it?

Its foolish to think that just because some people do overload their sockets/cables that everyone should have to have grossly oversized conductors. A well organised and fitted kitchen with a well designed and fitted electrical circuit will never have the problem JohnD pointed out.

He also pointed out that the world is changing with many things like tumble dryers that weren't available when the system was worked out.

If sockets run hot when the householder uses them - then they should be redesigned. Not only that, insulation values change yearly and houses have heating systems they never had before.

If the system is faulty ( ie runs hot or cannot handle a bit of insulation) then change the system and build in a bit of future proofing.

When a house costs a half million or more - what's a bit of copper wire?

 

[davy_owen_88]

He also pointed out that the world is changing with many things like tumble dryers that weren't available when the system was worked out.

If sockets run hot when the householder uses them - then they should be redesigned. Not only that, insulation values change yearly and houses have heating systems they never had before.

If the system is faulty ( ie runs hot or cannot handle a bit of insulation) then change the system and build in a bit of future proofing.

When a house costs a half million or more - what's a bit of copper wire?

Double sockets run hot when 2 heavy loads are connected... simple solution: don't connect 2 heavy loads to one double socket. There's no need to change the regulations and upgrade everything when all it takes is a bit more thought put into designing a system to limit this occurring.

It all comes down to the fact that the system isn't faulty, its the people using the system not being educated in that systems limits. As soon as people realise these limits there are no problems.

It's another plus point to Part P. Kitchens have the highest loading of a standard house. All electrical work should be carried out by a competent electrician. Any competent electrician will ensure there are sufficient sockets and other means to prevent overloading of a socket.

Davy

 

[JohnD]

My utility room (where the washer and drier are) has a wallfull of single sockets

The kitchen (with undercounter appliances) has singles under the counter

And of course a dedicated radial for the freezer and one for the oven

 

[joe-90]

He also pointed out that the world is changing with many things like tumble dryers that weren't available when the system was worked out.

If sockets run hot when the householder uses them - then they should be redesigned. Not only that, insulation values change yearly and houses have heating systems they never had before.

If the system is faulty ( ie runs hot or cannot handle a bit of insulation) then change the system and build in a bit of future proofing.

When a house costs a half million or more - what's a bit of copper wire?

Double sockets run hot when 2 heavy loads are connected... simple solution: don't connect 2 heavy loads to one double socket. There's no need to change the regulations and upgrade everything when all it takes is a bit more thought put into designing a system to limit this occurring.

It all comes down to the fact that the system isn't faulty, its the people using the system not being educated in that systems limits. As soon as people realise these limits there are no problems.

It's another plus point to Part P. Kitchens have the highest loading of a standard house. All electrical work should be carried out by a competent electrician. Any competent electrician will ensure there are sufficient sockets and other means to prevent overloading of a socket.

Davy

Load of piffle. If there is a double socket it's there to be used. If it can't handle the load it shouldn't be there.

It's like saying your car brakes are good on small hills but not big ones.

 

[JohnD]

It's lucky we're "in the know" now