Ring extension load

[EFLImpudence]

As it's just a stud wall, perhaps you could replace the cable with 4mm² cable and fit two single sockets.

This would involve fitting a larger back box - a dual , though.

 

[DetlefSchmitz]

Yeah, I thought about that. It would break the ring final rules though (two sockets). (May be the best of a bad job though). To do it within the rules you would need to pull two 2.5mm cable through. And it sounds like the cable passes through two studs so unless the holes are known to be big...

 

[EFLImpudence]

I disagree about breaking the ring final rules - it just is not mentioned.

 

[Risteard]

A BS 1363 double socket outlet is rated for 20A. This is verified by testing one side with a slight overload (14A) and the other with 6A for perhaps an hour.

No BS 1363 double socket is rated above 20A - the Standard requires 20A rating and they must not be used to supply more than this.

 

[Echo the husky]

Seems easiest option now is to use the washing machine off the spur and the dryer off the extension cable to other socket.

If you really have to use an extension lead (I wouldn't) use it for the washing machine which is a much lighter load. The TD is a constant heavy load and often results in overheating, usually at the now very poorly made trailing socket contacts and cheap 13A plugs. Also many modern leads are now only rated for 10 amps for some stupid reason, it seems to be very common with newer Chinese leads etc.

If it was me I would be putting the effort in to either change the 2.5mm² to 4.0mm² cable or getting another 2.5mm² cable in to extend the ring, and wire in 2 single sockets.

 

[securespark]

I can't understand why the (originally-fitted) switch was overheating.

Over my 30 years working as a spark, I have fitted a few 13A SFCU's feeding several outlets.

Not seen them overheat. Have had a 13A fuse blow, but not overheating or switch damage.

Could that have been down to poor connections or a cheap switch?

 

[skyhawker]

I can't understand why the (originally-fitted) switch was overheating.

Over my 30 years working as a spark, I have fitted a few 13A SFCU's feeding several outlets.

Not seen them overheat. Have had a 13A fuse blow, but not overheating or switch damage.

Could that have been down to poor connections or a cheap switch?

I believe the switch was a cheap one, but it is interesting now you mention why didn't the fuse blow if the appliances were pulling over 13amps?

 

[Iggifer]

A BS 1363 double socket outlet is rated for 20A. This is verified by testing one side with a slight overload (14A) and the other with 6A for perhaps an hour.

No BS 1363 double socket is rated above 20A - the Standard requires 20A rating and they must not be used to supply more than this.

You might wanna have a word with MK technical then

 

[flameport]

why didn't the fuse blow if the appliances were pulling over 13amps?

A 13A fuse is so called because it will allow 13A to pass indefinitely without failing.
Above 13A it will fail at some point, depending on how long the overload is applied and the extent of the overload.
With a small overload it could be hours before it fails. A moderate overload could still be tens of minutes before failure.

 

[PBC_1966]

While it's true that once you have a double 13A socket in place there's nothing to stop anyone from plugging two 3kW loads into it, in most locations that's unlikely to happen. To install one with the intent of using it for two such loads is, in my opinion, poor practice given the manufacturers' ratings (and possibly the spur cable rating, depending upon installation method), especially given the duration of the loads. A dryer could well be running for an hour and half or more (even 3 hours or more with little break if somebody is doing a couple of large loads), and while the washer uses that power only during the heating cycle, it's not unusual to find a washer plumbed for cold fill only, for which on some settings (near boiling, higher water level) the heating element could be running for half to three-quarters of an hour.

 

[ban-all-sheds]

The current carrying capacity was decided before 230v was used in calculations.

And when the nominal voltage was 240, the ± either side of that gave a range pretty much the same as the ± either side of 230 gives us now, so the use of a different but just as valid nominal value has no impact on cables.

No matter how much you wish it did.

 

[ban-all-sheds]

No BS 1363 double socket is rated above 20A

Wrong.

the Standard requires 20A rating and they must not be used to supply more than this.

Wrong.

 

[Risteard]

Wrong.

On your part...

 

[ericmark]

As to 13A double sockets I have seen where they are rated 13A each and also 13A for the pair the latter normally where the socket has filters or built in RCD. Point is there is no one ratting fits all.

I have had a double socket feeding washer and drier for years without a problem switched with a 20A switch. Not saying correct but nothing has gone wrong.

A good quality FCU should blow the fuse before the unit is damaged I would say there is a fault with the FCU.

The BS7671 only states "under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods the current-carrying capacity (Iz) of the cable." (433.1.5) the FCU fitted ensured this was the case. Removing it means you need to complete the calculations to ensure this is still the case.

The problem with a ring is any loads which are not central can cause overloads to one leg of the ring. In my kitchen extension loads are near the centre of the ring so using a 4mm² cable to feed extra sockets would not be a problem, however it all depends on how central the point is to if using 4mm² cable would comply with 433.1.5 we have no idea how central it is in this case so we should not be offering this as a method.

Appendix 15 states one way to ensure there is no overload is connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit i.e. fixed appliances and washing machines and tumble driers are too heavy to be considered as portable. So the washer, tumble drier, dish washer, oven, and immersion heater all exceed the 2kW so should have dedicated circuits. This is often covered by having a kitchen ring which is dedicated to kitchen and all socket outlets are reasonably central.

It is the "central" or "non central" loading which is the problem. I would be getting the electrician who rewired back or at least getting him to say what load can be put on that circuit. This is not really a problem which can be solved remotely.

 

[ban-all-sheds]

On your part...

Really?

So what do you say about the fact that some sockets are made to cope with >20A?

What do you say about the fact that BS 1363 does not mandate a maximum current carrying ability?

What do you say about the fact that you seem unable to understand the idea that when a standard says "the {whatever} must be able to cope with a {whichever} of a {howmuch} magnitude" that that does not mean that the {whatever} must not be made able to cope with more?

the Standard requires 20A rating and they must not be used to supply more than this.

Please show us where the standard says that.

Or fail to do so and accept that you are wrong.