Problem with Ring Main

[securespark]

Especially if it then catches fire...

 

[Taylortwocities]

Because that is what it says in my BS7671:2008

Not as a regulation. In the BRB (BS7671:2008) it is also an informative Appendix 15. It gives four suggested methods of reducing the effect of using current carrying equipment for long periods on a ring final.
Another is locating socket outlets to provide reasonable sharing of the load around the ring.

 

[ban-all-sheds]

And a tumble dryer may be running at full load for several hours continuously. It's the nastiest load in the typical house from that point of view.

If your tumble dryer takes several hours to do a load, you should get a new one.

 

[ericmark]

And a tumble dryer may be running at full load for several hours continuously. It's the nastiest load in the typical house from that point of view.

If your tumble dryer takes several hours to do a load, you should get a new one.

Depends on model but some are designed that way. OK would be below 2 kW as that is the whole idea long time and low watts, but Joules used per cycle are less than the hi heat models designed to be used with off peak power. All the spec about them shows they are better than the fast models, some do still have the option for a fast dry.

Not as a regulation. In the BRB (BS7671:2008) it is also an informative Appendix 15. It gives four suggested methods of reducing the effect of using current carrying equipment for long periods on a ring final.
Another is locating socket outlets to provide reasonable sharing of the load around the ring.

I have had the argument before as to if the appendix is part of BS7671:2008 and the answer is simple are you tested with questions from the appendix when sitting the C&G2382 answer is yes, so clearly it is part of the regulations. However be it a recommended method to prevent overload of or a regulations does not really matter, even the regulations are not law, it clearly suggests the like of washing machine, tumble drier, dish washer, and oven should not be on the standard ground floor ring.

Since a new house one would assume it would have a dedicated laundry ring or kitchen ring!

 

[ban-all-sheds]

I have had the argument before as to if the appendix is part of BS7671:2008 and the answer is simple are you tested with questions from the appendix when sitting the C&G2382 answer is yes, so clearly it is part of the regulations.

Nobody is saying that it is not "part of the regulations". Anybody with a copy can see that it is part of them on p453.

The argument you keep having seems to stem from your apparent inability to distinguish between normative and informative.

it clearly suggests the like of washing machine, tumble drier, dish washer, and oven should not be on the standard ground floor ring.

No it doesn't.

 

[EFLImpudence]

Since a new house one would assume it would have a dedicated laundry ring or kitchen ring!

Surely that would result in the same situation.

Appendix 15 only stipulates cooking appliances over 2kW (only 8.3A).
Also, surely, ring is not the relevant factor as a 32A radial would have the same result but App.15 does not seem to say the same for radials - even a 20A one.

If you are saying that these appliances must not be plugged in to a socket circuit then what is the point of a multiple-socket circuit in a kitchen?

 

[ban-all-sheds]

Appendix 15 only stipulates cooking appliances over 2kW (only 8.3A).

It advises that those, and immersion heaters, space heating and loads of a similar profile not be supplied via a ring.

Not any and every >2kW appliance.

This is worth reading - it refers to the old "0.67In", rather than 20A, but is still very relevant.

 

[EFLImpudence]

Yes, beg pardon.

I was just relating to the items mentioned - kitchen appliances.

 

[ericmark]

I will admit I have a problem with the word dedicated. To my mind the kitchen or laundry ring final if it is a ring final and not cables in parallel is dedicated to kitchen appliances, it is not for general use. Once we take the washing machine, tumble drier, oven, dish washer, and immersion heater plus items over 3kW away from the general ring there is very little left which has any real load. Even the kettle is still used from the kitchen ring final.

So returning to the reason for the post, if there is a kitchen ring final which is unaffected by splitting the ring in question into to radials then even with 16A MCB/RCBO fitted then it is unlikely to be a problem. However if the high power users are on the ring in question then the idea of splitting is very different and there is a high chance of overloads tripping the MCB/RCBO.

 

[EFLImpudence]

You cannot have a dedicated socket circuit.

Dedicated means designed and installed to supply a certain item or certain items of known loading.

 

[ericmark]

My thanks to BAS this shows how most of the power is used in a kitchen. I am not sure how they measured all this? For the few pints of water my dish washer and washing machine use half an hour heating seems excessive. In both cases the supply sockets are not easy to reach or I would measure. Next after the kitchen/laundry room is the garden. High pressure washers, lawn mowers etc. But when using them unlikely using more than one item at any one time.

 

[WabbitPoo]

Hi All,


They have found an issue with the downstairs sockets ring between a socket in my living room and a socket in my utility room (which are at opposite sides of the house).

Did they say what the issue is? Out of interest, how would this have been narrowed down?

 

[ericmark]

You cannot have a dedicated socket circuit.

Dedicated means designed and installed to supply a certain item or certain items of known loading.

So

740.55.7 Socket-outlets and plugs
An adequate number of socket-outlets shall be installed to allow the user's requirements to be met safely.
NOTE: In booths. stands and for fixed installations, one socket-outlet for each square metre or linear metre of wall is generally considered adequate.
Socket-outlets dedicated to lighting circuits

if it can be dedicated to lighting, then why not dedicated to kitchen use?

(b) a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment.

also seems to say a socket can be dedicated. OK I know this is old version of BS7671:2008 and talking about a special location but it does seem to point in being able to have a dedicated socket circuit.

 

[EFLImpudence]

if it can be dedicated to lighting, then why not dedicated to kitchen use?

740 relates to temporary installations at fairgrounds etc. (in my BYB - is it the same?).

I assume the load would be known and designed accordingly.
This is not the case in the usual domestic situation.

An adequate number of socket-outlets shall be installed to allow the user's requirements to be met safely.

Isn't that the wrong way round for items on a dedicated circuit? Although I suppose it is covered by the "safely" at the end.
Does that apply to a usual socket circuit?

also seems to say a socket can be dedicated.

Is it not possible to plug in anything else?
If you write 'Television' on a socket does that limit the possible loading?

it does seem to point in being able to have a dedicated socket circuit.

Not really. Would it be possible to plug in some extra items?

 

[ericmark]

I suppose you could use a Walsal plug

but the whole idea was that something known to not need RCD protection but never the less could trip a RCD and cause danger as a result, for example food getting too hot that you can provide a dedicated socket. Since in the main they would have a moulded plug the Walsal plug would not really work.

So yes valid question a 13A socket in the loft with "active TV pre-amplifier only" does not stop anyone from plugging in an electric drill, but if they do and as a result are plunged into darkness they could hardly complain unless they are American, in which case adults do need treating like children at least if you read about court cases.

But in this case all we are asking is if the ring final with a fault will normally supply a number of high powered appliances. Not really worried about anything else.