No rings, we are going radial what are the practicalities?

[MikeSharp01]

So we are going to go for 4mm radial wiring and I was wondering what the practical challenges are.

 

For instance most sockets are specified for 2x4mm in each terminal so spurs are a challenge and squeezing 2x4mm into the back box of the socket looks like a pain.

 

How are these issues best approached and are there any more I should be considering?

[elite]

I'd avoid branches in 4mm as terminating is a pain and you want to avoid junctions

 

Have you calculated the expected load for each circuit? I'd be surprised if most couldn't be handled on a 20 amp or 16 amp radial in 2.5mm - A 32amp 4mm circuit would be circa 7kw.

[Onoff]

Good luck getting 2 4mms in some accessories let alone 3.

[Thorfun]

why no rings? all our lighting is radial but our sockets are one ring per room so kind of a halfway house. seemed like a logical compromise to me and my sparky.

[TonyT]

Bigger consumer unit.

more cost for rcbos 

more cost for cable 

 

However  for minimising inconvenience to trips  it’s a plus.

[Onoff]

Deeper, 47mm back boxes can help but that has knock ons. A deeper service cavity potentially etc.

[Wil]

20A radials in 2.5mm for the win!

[Thorfun]

3 hours ago, TonyT said:

Bigger consumer unit.

more cost for rcbos 

more cost for cable 

 

However  for minimising inconvenience to trips  it’s a plus.

these were exactly our thoughts and why we went one ring per room. that way if a room trips it doesn't take out the whole floor or any other rooms.

[Mike]

I've a rewire coming up in France, where radials are mandatory. Power circuits are either 8 sockets on 16A, or 12 sockets - the maximum number permitted on one circuit - on 20A. A double counts as 2 sockets.

 

Apart from the hob on 32A, everything else is 2A, 10A, 16A or 20A. That's 24 circuits in total, but by the time circuit breakers, dimmers, contactors, power supplies, load-shedder and other accessories are added, plus the 20% mandatory 'unused' allowance, I need a 72-way consumer unit for a 1 bed apartment!

 

Together with the space for the meter and master switch, plus the mandatory communications connection unit & space for the internet box, it's not far off a full floor-to-ceiling stack.

 

Edited May 10, 2023 by Mike

[MikeSharp01]

12 hours ago, Mike said:

a 72-way consumer unit for a 1 bed apartment

 Cripes - I wanted to get away with 14 ways. 

[Carrerahill]

On 10/05/2023 at 11:15, MikeSharp01 said:

So we are going to go for 4mm radial wiring and I was wondering what the practical challenges are.

 

For instance most sockets are specified for 2x4mm in each terminal so spurs are a challenge and squeezing 2x4mm into the back box of the socket looks like a pain.

 

How are these issues best approached and are there any more I should be considering?

OK fine, not really any reason electrically and its becoming more common, however, consider 2.5mm² 20A radials for smaller areas/rooms etc. that will make terminating easier and save you some money on copper. Small power loads in houses are not really heavy at all, it was different when every lamp was 100W and people had the odd 2kW fire here and there but consider what you actually plug in. 

 

Treat kitchens differently, I did an appliances (grid switch) circuit and a small power circuit with a dedicated 16A radial for the fridge/freezer.