Are there any sparkies in the house?

[Beardy]

18th edition radial circuits in a domestic installation.
Can you have to separately protected radial circuits in the same room for load splitting. Given that both will be one the same phase I can’t see why you wouldn’t be able to do so. I suppose the alternative would be a 4mm² 32amp protected single circuit, but it seems two separate 2.5mm² 20amp protected circuits would give more flexibility.

What do other electrically minded people think?

[grams]

AIUI you can split up circuits any way you please.

What you propose is routinely done in any room with an open plan kitchen or similar.

(unless you think there's something specific in 18th edition that might have changed the rules)

[Feanor]

That should be no problem.

Do everything possible to avoid working with 4mm² in normal socket backing boxes. It's a nightmare.
Doubly so if you are wrangling 2 cables to daisy-chain.

Out of curiosity, is there any particular reason you want to use radials rather than rings?
What's the downside of the extra run of 2.5 back from the end of the radial to ringify it?

[hbunnet]

Do everything possible to avoid working with 4mm² in normal socket backing boxes. It's a nightmare.
Doubly so if you are wrangling 2 cables to daisy-chain.

+1 on not 4mm. I happened to have  4mm² available for a job with good access and plenty of time. I really wanted to make a neat job, I failed, electrically safe but fugly.

[Beardy]

Out of curiosity, is there any particular reason you want to use radials rather than rings?

Fault liability really. If you get a disconnect on a radial, everything down chain from that point either stops working or becomes intermittent. Get the same on a ring and you probably wound know about it and such a disconnect creates fire hazards. Not an absolute, obviously, but enough of a concern to give me pause. Fitting radials in a room with an active fire place is less of a hassle as well.

[Kim]

Ring mains are a work of Stan.  Is that not enough?

[Beardy]

Ring mains are a work of Stan.  Is that not enough?

I agree, an more importantly, so does BigClive which rather seals the deal.

[Diver300]

Ring mains are a work of Stan.  Is that not enough?

I agree, an more importantly, so does BigClive which rather seals the deal.

I think ring mains are neat and easily understandable. I'll look up what BigClive has to say about them

I will admit that the bodge-artist who did some of this house didn't understand ring mains.

[valkyrie]

Ring mains are a very efficient use of copper, which was the key consideration when they were first adopted. They work well, so I'm not seeing why anyone would regard them as the work of stan.

[grams]

What could possibly be bad about putting 20A rated cable behind a 32A breaker?

[Kim]

Ring mains are a work of Stan.  Is that not enough?

I agree, an more importantly, so does BigClive which rather seals the deal.

I think ring mains are neat and easily understandable. I'll look up what BigClive has to say about them

I will admit that the bodge-artist who did some of this house didn't understand ring mains.

Neat and easily understandable on paper, and on nice neat fresh installs.

They have failure modes that don't hold up well in the presence of successive bodgers, confusing conversions to flats and the like.

Like the FOREIGNS, I'm generally inclined towards smaller circuits on more breakers: You get an extra degree of overcurrent protection for the appliance and trips don't take out as much stuff.

That said, I can see the logic in using a ring circuit for a kitchen.

[Beardy]

The kitchen is my main use case for going radial. I can split the white goods from the cooking stuff and have a third circuit for the user stuff in the dining area. That said, we’ve not had a trip on the kitten circuit for quite a while, so maybe it was a dodgy appliance.

[valkyrie]

Most countries that use radial circuits also use unfused plugs, so the lower rated MCBs are needed to protect the appliance flex. 20A rated cable is perfectly fine with a 32A breaker if it’s doubled up.

[aidan.f]

And back to the fire risk. Arc fault detecting mcbs are now a 'thing'  best used on radial circuits.