jimmyhorns:

I'm running through the options with regards to terminating a 4mm2 ring when it comes to the sockets. For some of the 2G sockets there is plenty of space to easily / reliably terminate the 4mm2 cable, in others not so much.


What would be a whole lot easier (there is plenty of space as I fitted 35mm back boxes) would be to loop in and out via a couple of wago 221 3-way connectors using the 3rd way as a spur to the socket, allowing just a single cable needing to be clamped down at the socket terminal itself.


I'm sure I won't have been the first to have thought of this.


Thoughts please? The only limitation I can see is that I would'nt be able to spur off the socket (but could of course just use a wago with more ways).


It has been a long week and I just wanted to sense check this........


Thanks in advance


James

Is a 4.0mm2 ring really required?


Z.

Sparkingchip:

Really you are looking at getting (2 x4.0) + 2.5 into the terminals to allow for a spur, which should be perfectly achievable because you could be using the same fittings for a 4.0 mm radial circuit.


You should not be having a problem in the first place.


Andy Betteridge.

Agreed ... BUT you may be surprised that spurring off a 4 mm² ring or radial exceeds the terminal capacity stated in BS 1363-2:

11.5 Line and neutral terminals in fixed socket‑outlets shall permit the connection, without special preparation, of one, two or three 2.5 mm² solid or stranded or of one or two 4 mm² stranded conductors as given in Table 4 of BS 6004:2012.

and

11.6 Earthing terminals in fixed socket‑outlets shall permit the connection, without special preparation, of one, two or three 1.5 mm² or 2.5 mm² solid or stranded or of one or two 4 mm² stranded conductors.

This terminal capacity is what's quoted in a number of manufacturer's ranges ... so the OP really does have a point, especially if you want to spur off anywhere it's a good idea, and perfectly reasonable in my opinion.

gkenyon:

Installation method may preclude 2.5 (e.g. methods 101# or 103) as the current carrying capacity has to be at least 20 A.


Volt drop is another potential reason - assuming 30 mA RCD protection is provided at the DB or CU as ring is feeding socket-outlets - ring length end-to-end exceeds 106 m {see Table 7.1(i) of OSG}


Or perhaps it was simply in a specification for some reason ...

You are spot on with the reasoning here - it is a combination of installation methods (including 101 and 103 in places), combined with there being some high load appliances helpfully at the furthest point from the CU. Ring length on one of the circuits is just shy of the 106m limit (103m).


You certainly cannot fit anything more than 2 x 4mm2 into these sockets safely and not have any of the copper showing, I have tried!


Anyway, what to use for 1st fix is rather academic now.......... as its 4mm2 thats in.



I am slightly biased as I really really like wagos, especially the 221. I also struggle with my back, so being bent over doing sockets isnt the greatest and minimising strain / effort is high on the priority list.


It is a lot easier to terminate 4mm in a wago than to torque down a screw. Its also a lot easier to manipulate them as singles rather than having to draw them together as a pair. Its also easier to not have to manipulate the socket and the cable once one pair of cables are terminated.


I usually pair easier with safer, which is never a bad thing.


Just counting the sockets there are 25 in this installation and I can happily do these as a batch job on the desk, ready to be fitted to the waiting wagos in the back box. I estimate the time saved will more than pay for the wagos (<£30).



Thanks for all of your answers - so far I have not read any issues or downsides with the plan.