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.

 

[AndyPRK]

The important thing to consider is the kitchen. And to save you buying more reals of cable than necessary, the answer is to put a ring in the kitchen.

Lights. Depends if you have ceiling roses or fancy lights that only accept 1 cable !

I’ve know upstairs to use roses
And downstairs to loop at the switch.
Which is sensible.

 

[eveares]

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.

These days, not running/having a neutral at a light switch is silly imo in the age of smart light swicthes and IoT stuff in general, hence I would allways loop at the switch and not the rose myself.

As for sockets, I prefere radials over ring final circuits due to ease of extending them down the line and ommiting the risk of a broken ring final circuit. I typicly use 32A 4mm for kicthens/utility rooms and 20A 2.5mm for other general areas.

 

[EFLImpudence]

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,

You always quote these lengths but how high is a tree compared with the combined length of its branches?

 

[Harry Bloomfield]

These days, not running/having a neutral at a light switch is silly imo in the age of smart light swicthes and IoT stuff in general, hence I would allways loop at the switch and not the rose myself.

Nowt to stop you looping at the rose, then just taking a neutral down to the switch.

 

[bilabonic]

Looks like ring up. Ring down and kitchen ring then.
Lighting downstairs with feed to switch's as it has downlights.
Upstairs I might do 3plate/feed to pendant.

Thanks

 

[EFLImpudence]

Looks like ring up. Ring down and kitchen ring then.

 

[bilabonic]

Upstairs ring main.
Downstairs ring main.
Kitchen ring maim.
Plus separate feed for boiler.

Upstairs lighting
Downstairs lighting.

That makes it x6 RCBOs.

I will also be fitting wired smokes uo and downstairs and probably a a combined heat/smoke in kitchen. All interlinked.
Are you guys feeding these of their own feed or just tapping into lights?

Thanks.

 

[EFLImpudence]

Upstairs ring main.
Downstairs ring main.
Kitchen ring maim.

How or why have you come to that conclusion?

 

[flameport]

How or why have you come to that conclusion?

The usual ask for advice, then ignore all of it and do what they were going to do anyway.

 

[pete01]

Sockets...

20 amp Radial upstairs
20 amp Radial downstairs

32 amp ring in the kitchen.

Lights.

Two plate if completely new chases

Three plate if you're going to re-use the old sw drops (or try to)

 

[AndyPRK]

There are always arguments both ways on smoke alarms. But as this is fresh, you may as well run the supply back to the CU.

You can do either then.

I quote like having burglar alarm and smokes on the same rcbo. B6

You could even put the boiler on that too if you wanted to save money.

Running everything back to CU leaves options open and easy for diagnostic work.