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.

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.