Rinf Main addition. 20 or 30 amp junction boxes?


I am adding two extra double sockets to my kitchen ring main and I was proposing to fit two 20 amp junction boxes to enable me to add the extra sockets. A friend said I should fit 30 amp junction boxes instead of 20 amp Is this essential? So far I have not seen any 30amp boxes in B&Q or Wickes Blair
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Well they exist, and yes you should use them. B&Q certainly have them. You are unlikely to get all the conductors safely and securely connected in a 20A junction box. Indeed, it is often suggested to go for an even higher current rating of junction box, which is often easier to make reliable connections in.
Remember that terminal connections must remain accessible for testing and maintenance (and not, for example, buried inaccessibly inside the building fabric).
I am somewhat concerned that you don't sound compitent to undertake this task, but it sure is better to ask questions than to plough on regardless.
--
Andrew Gabriel

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Firstly in a ring main proteced at 32A their will certainly be less than 20A flowing in the two paths. Also 2.5mm cable is itself rated at 20A (worst case). For these two reasons there is no problem with the OP using 20A junction boxes at all providing one is used for each leg.

Correct.
I see nothing in the OP's posting to suggest that. It seems to me he/she has considered all the right things and knows the questions to ask. It's not a difficult job and I'm sure he/she is up to it.
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With a 32 A protection, this should be the weekest point of the circuit, not a 20A junction. The fuse / breaker MUST blow long before any of the wiring or junctions, therefore the junction should be rated in excess of 32A.
Granted the ring main is a "ring" but should a wire break in the ring, suddenly the 20A junction becomes the weak point and suffice to say phone the fire brigade before the insurance company.
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Probably best to change the 2.5 cable on the ring as well because that is not rated at 32 amps.
Adam
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Thanks for your replies-Most helpful. Yes I am reasonably competent but careful. Blair
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in polythene and insulation tape and plastered in a cutout in the plasterboard. Only found when removing wallpaper from kitchen. No idea how long it had been there.
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