Does a tumble dryer require its own socket?

[ericmark]

I was intending to correct the statement that fires were not caused by fluff, nor overloaded sockets. This would seem to be a message having a negative effect.

I am sure all are dangers, fluff built up, poor connections on plug or socket, and contaminated clothes, as to how anyone works out which was the cause when they see this

I really don't know. The picture was from a report, "Whirlpool recall of fire risk tumble dryers begins today" and clearly there have been some tumble driers which were of poor design. "This action comes more than three-and-a-half years after Whirlpool first admitted that it had a fire problem with vented and condenser dryers, branded Hotpoint, Indesit, Creda, Swan and Proline, made between April 2004 and October 2015." says the report.

The picture further down the report clearly shows a vented drier. A Google for "heat pump tumble dryer fire risk" shows the same results as "tumble dryer fire risk" in the main, I did find one report however don't recognise the organisation so it could simply be an advert.

We have to consider how the drier works, it passes air through the clothes which is drier than the clothes in the drum, it is made drier either by using a fresh supply all the time, or extracting the moisture from recirculated air, the way if extracts the moisture is to cool the air, the cooler the air, the more moisture extracted, so we have cooled by air in the room, cooled by cold water, and cooled with a heat pump, the heat pump in general can cool the air to a lower temperature to using cold water or ambient air, so it does not need to heat the air as much to extract moisture from the cloths.

In general, it runs around 20ºC cooler than the air or water cooled, and it also controls the temperture, the early vented tumble triers had no temperture control, except for a over temp cut out. Where with the heat pump drier, the energy monitor shows it starts to do a mark/space ratio if the air gets too hot.

I fail to see how we can compare the modern heat pump drier with the old vented type, they are so diffrent, there was at one point a vented drier designed to work over night, is had some thing like a 500 watt heater instead of 2000 watt, and was designed to take around 3 hours, using off peak supplies.

I note my heat pump tumble drier if set for delayed start, tumbles the clothes every so often while waiting for start time, same with washing machine, it does seem wrong way around to me, more important to tumble every so often once finished.

 

[JohnW2]

Returning to the issue of 'overloading of double sockets', the more I think about it, the more I wonder whether it is actually a significant issue atall.

It is true that a lot of the reports we hear of thermally-damaged BS1363 plugs/sockets relate to double sockets, but that could simply be because double sockets are much more common than single ones.

In all (not many) cases of such thermal damage I can recall having experienced, it has been clear that the problem arose in the plug, in the vicinity of the fuse (hence probably due to poor connections to the fuse), with heat eventually transferred through the L pin to do dome damage to the socket in the vicinity of that pin. I cannot recall having seen situations in which it looks as if the problem may have originated in the socket. Furthermore, very few parts of a double socket carry the combined current of both outlets, and they are primarily fat pieces of brass or copper.

The only case I can recall in recent years was extensive damage to a plug (in vicinity of fuse) and associated parts of the socket arose with a 2 kW fan heater - but that was plugged into a single socket.

I therefore have to wonder how sure we are that the reports we hear are actually anything to do with the fact that the socket was a double one (whatever its "rating", and regardless of what was plugged into the other outlet). What do you think?

Kind Regards, John

 

[SUNRAY]

Returning to the issue of 'overloading of double sockets', the more I think about it, the more I wonder whether it is actually a significant issue atall.

It is true that a lot of the reports we hear of thermally-damaged BS1363 plugs/sockets relate to double sockets, but that could simply be because double sockets are much more common than single ones.

In all (not many) cases of such thermal damage I can recall having experienced, it has been clear that the problem arose in the plug, in the vicinity of the fuse (hence probably due to poor connections to the fuse), with heat eventually transferred through the L pin to do dome damage to the socket in the vicinity of that pin. I cannot recall having seen situations in which it looks as if the problem may have originated in the socket. Furthermore, very few parts of a double socket carry the combined current of both outlets, and they are primarily fat pieces of brass or copper.

The only case I can recall in recent years was extensive damage to a plug (in vicinity of fuse) and associated parts of the socket arose with a 2 kW fan heater - but that was plugged into a single socket.

I therefore have to wonder how sure we are that the reports we hear are actually anything to do with the fact that the socket was a double one (whatever its "rating", and regardless of what was plugged into the other outlet). What do you think?

Kind Regards, John

As I said before I limit long duration loads on a double 13A socket to around the 13 ishA thing like stage lighting where the load could be fixed for 3 hours for a show of all day for a conference. but at home our 3 main white goods items have variously shared double sockets as the kitchen alters for decades.

 

[JohnW2]

As I said before I limit long duration loads on a double 13A socket to around the 13 ishA thing like stage lighting where the load could be fixed for 3 hours for a show of all day for a conference. but at home our 3 main white goods items have variously shared double sockets as the kitchen alters for decades.

Sure - if one has concerns,then they will be greater with the sort of 'long duration' high loads you mention than in most domestic situations.

However, as I wrote, I'm not convinced that it is the fact that it is a double socket that is ever the issue, particularly given that, when it occurs, serious over-heating nearly always seems to originate in the plug, not the socket.

In other words, if I had such 'concerns', I think I would be just as concerned with a 'long duration' load approaching 13A being supplied froma (plug and) single socket as I would be with 20 A, or even 26A,being supplied by a double socket - because, as above I think the problem may well relate to the plugs, not the socket.

 

[Risteard]

Millions of people probably have tumble dryers supplied by a double socket that also supplies another significant appliance.

The 'risk'' is extremely small (and really shouldn't exist at all if double sockets always did "what it says or should say) on their tin"), but to have an appliance like a dryer supplied from its "own socket" (which could be a double one, if the other outlet wasn't used for anything 'high powered') is even 'safer'.

Kind Regards, John

The risk isn't small. A tumble dryer should never be supplied from a double socket-outlet.

 

[SUNRAY]

Sure - if one has concerns,then they will be greater with the sort of 'long duration' high loads you mention than in most domestic situations.

However, as I wrote, I'm not convinced that it is the fact that it is a double socket that is ever the issue, particularly given that, when it occurs, serious over-heating nearly always seems to originate in the plug, not the socket.

In other words, if I had such 'concerns', I think I would be just as concerned with a 'long duration' load approaching 13A being supplied froma (plug and) single socket as I would be with 20 A, or even 26A,being supplied by a double socket - because, as above I think the problem may well relate to the plugs, not the socket.

Yes, on page 1 I mentioned the problem is our horrible plugs which overheat.

 

[JohnW2]

The risk isn't small. A tumble dryer should never be supplied from a double socket-outlet.

Despite the apparent assertion, that is merely your view.

As I've said, I'm far from convinced that it makes much/any difference whether a tumble dryer is supplied from a single or double socket - since, when overheating and thermal damage arises, it nearly always seems to originate in the plug (in association with the fuse connections), not the socket.

 

[SUNRAY]

Sure - if one has concerns,then they will be greater with the sort of 'long duration' high loads you mention than in most domestic situations.

However, as I wrote, I'm not convinced that it is the fact that it is a double socket that is ever the issue, particularly given that, when it occurs, serious over-heating nearly always seems to originate in the plug, not the socket.

In other words, if I had such 'concerns', I think I would be just as concerned with a 'long duration' load approaching 13A being supplied froma (plug and) single socket as I would be with 20 A, or even 26A,being supplied by a double socket - because, as above I think the problem may well relate to the plugs, not the socket.

Given the option I'd much prefer to be presented with a an older 5A BS546 for a constant 3KW load than a BS1363
I worked in a theatre where a lighting board running 8 lights, upgraded from 500W to 1KW the feed being via a 15A BS546 and 30A MCB all 8KW was regularly on for an entire show.

 

[JohnW2]

Given the option I'd much prefer to be presented with a an older 5A BS546 for a constant 3KW load than a BS1363
I worked in a theatre where a lighting board running 8 lights, upgraded from 500W to 1KW the feed being via a 15A BS546 and 30A MCB all 8KW was regularly on for an entire show.

You may well be right, but that's obviously not what we're discussing, and UK domestic installations are now effectively stuck with BS1363 plugs/sockets.

 

[SUNRAY]

You may well be right, but that's obviously not what we're discussing, and UK domestic installations are now effectively stuck with BS1363 plugs/sockets.

Yes I appreciate that, I guess I was just indicating the biggest issue is the presence of the fuse/the way it's fitted. Without it the connector is very likely to handle the full rated currentwithout problems

 

[JohnW2]

Yes I appreciate that, I guess I was just indicating the biggest issue is the presence of the fuse/the way it's fitted. Without it the connector is very likely to handle the full rated currentwithout problems

Quite so. As I said, the more I think about it, the more I come to doubt that double sockets (whatever their perceived 'rating') have got anything to do with the occasional problems we see. As you say, it appears that it is the plugs particularly their fuses, and the way the fuses are connected) that are the problem - so the overheating problems are probably almost as likely to occur with single sockets..

 

[Harry Bloomfield]

Quite so. As I said, the more I think about it, the more I come to doubt that double sockets (whatever their perceived 'rating') have got anything to do with the occasional problems we see. As you say, it appears that it is the plugs particularly their fuses, and the way the fuses are connected) that are the problem - so the overheating problems are probably almost as likely to occur with single sockets..

There is no way around it - the way fuses are designed to work. The more current they carry, the hotter they becomes, and in the confines of a plug, there is little opportunity for that heat to be adequately dissipated.

I seem to recall having come across a couple of outlets, where they have failed due to over-heating where internal 'bus-bars' are riveted.

 

[JohnW2]

There is no way around it - the way fuses are designed to work. The more current they carry, the hotter they becomes, and in the confines of a plug, there is little opportunity for that heat to be adequately dissipated.

I suspect that isn't usually the problem - i.e. I doubt that the heat inevitably generated by high current flowing through the fuse will often be enough to do 'thermal damage'. I think it's much more likely that the problem is the iffy connection between the fuses and their 'holders' - a view perhaps supported by the fact that the evidence seems to be that the damaging heat was generated primarily at one end of the fuse, rather than throughout its length

I seem to recall having come across a couple of outlets, where they have failed due to over-heating where internal 'bus-bars' are riveted.

Anything is possible, so I suppose that may sometimes happen, but I don't think I've ever seen that, and I feel sure that overheating in the plugs (close to the fuse) is far far more common.

 

[ebee]

Returning to the issue of 'overloading of double sockets', the more I think about it, the more I wonder whether it is actually a significant issue atall.

It is true that a lot of the reports we hear of thermally-damaged BS1363 plugs/sockets relate to double sockets, but that could simply be because double sockets are much more common than single ones.

In all (not many) cases of such thermal damage I can recall having experienced, it has been clear that the problem arose in the plug, in the vicinity of the fuse (hence probably due to poor connections to the fuse), with heat eventually transferred through the L pin to do dome damage to the socket in the vicinity of that pin. I cannot recall having seen situations in which it looks as if the problem may have originated in the socket. Furthermore, very few parts of a double socket carry the combined current of both outlets, and they are primarily fat pieces of brass or copper.

The only case I can recall in recent years was extensive damage to a plug (in vicinity of fuse) and associated parts of the socket arose with a 2 kW fan heater - but that was plugged into a single socket.

I therefore have to wonder how sure we are that the reports we hear are actually anything to do with the fact that the socket was a double one (whatever its "rating", and regardless of what was plugged into the other outlet). What do you think?

Kind Regards, John

Yes John, I am happy to agree with that in the main, not so much in opposition .

 

[ebee]

The risk isn't small. A tumble dryer should never be supplied from a double socket-outlet.

It is a good stance to take as a "Rule of thumb". Rules of thumb are just that and nothing else, the picture is far more complicated but rules of thumb have uses in general guidance.