Advice - First Fix Ring main or Radial?

[bilabonic]

Hi All

Industrial Spark by trade and done my 18th years ago.

Chasing walls etc and doing first fix.

Looking at loads of posts/threads it seems ring mains are no longer a thing with reduced wattage items etc.

Radials seem normal with a 20a RCBO.
Upstairs/Downstairs/boiler/kitchen.

Then lighting. It was old skool 3 plate.
Now it seems feed too switch and perhaps even a 3 core to pendant to get a neutral there.

Plus other speaks are doing a mix of both.

Radial or ring?
3 plate or switch feed?

Cheers

 

[plugwash]

Looking at loads of posts/threads it seems ring mains are no longer a thing

Some electricians don't like them, but I think anyone saying they are "no longer as thing" is stating their opinion as fact.

There are three main options for socket circuits, 20A radials, 32A radials and 32A rings.

A 20A radial is only enough for one full-sized load (e.g. kettle or electric heater) plus smalls. As such if I was wring my house with 20A radials. I would want one circuit per habitable room, plus one for kitchen countertop and fridge/freezer one each for washer/drier/dishwasher. That adds up quickly, I reckon if having a house wired with 20A radials I'd want ten or so socket circuits, compared to the typical three with 32A circuits.

32A radials require at least 4mm² and depending on installation method can easily require 6mm². The latter in particular as well as being expensive is likely to make termination very annoying.

So this IMO leaves the 32A ring as the best "bang per buck" option for sockets.

Now it seems feed too switch and perhaps even a 3 core to pendant to get a neutral there.

I think the big question is are you doing a complete "renovation" or are you trying to rewire in a way that is minimally disruptive.

Feed to switch and 3-core to pendant is the "future-proof" option. So if you are doing a complete "renovation" it's the way to go. OTOH old-school 3-plate may allow reuse of existing conduits.

 

[flameport]

Looking at loads of posts/threads it seems ring mains are no longer a thing with reduced wattage items etc.

They are not a thing because homes are not wired with a single circuit for all of the socket outlets any more.
Likewise the days of a fusebox with 3 fuses in it for the cooker, sockets and lighting are long gone.

Radials seem normal with a 20a RCBO.

Or any other rating.
All circuits are radials.
The ring for BS1363 socket outlets is one specific design created for a very specific set of circumstances that mostly don't exist any more.

There are still a few possible uses for a ring circuit with socket outlets such as some kitchens, but they are not a 'must have' item and certainly should not be considered as the usual way of doing things.

You can of course install whatever you want, but the point is to actually consider what is appropriate for the installation, rather than just slinging in 'standard' circuits because some guidance book that hasn't been updated in multiple decades said it was the thing to do.

3 plate or switch feed?

Either. The only modern adjustment is to use 3C&E between the light and the switch so that the neutral is available at the switch, and the light has switched and permanent line available at it.

 

[ericmark]

Technically you can have 106 meters of 2.5 mm² with a ring final, and 32 meters of 2.5 mm² with a 20 amp radial, so to replace one ring final may need 3 radials, so with the cost of RCBO's it is often cheaper to use ring finals. But it is all down to the amount of cable you will be using.