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
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
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
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
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.
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.
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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