Radial final circuit extend

andyp · Aug 29, 2024

A bit of clarification requested please.

In the garage I have a 20A device serving 1 double socket (2.5mm2 cable). I want to add a 2nd double socket. I know I can spur off the existing socket but the CU is exactly in the middle of the two sockets so it would mean less cable on the wall if I came direct from the CU for both sockets. Is this acceptable? Is it still classed as a spur? Or is this classed as a new circuit?

Thanks,

SPECIAL LOCATION · Aug 29, 2024

All cables connected to the same protective device are part of the same circuit.

A radial circuit can be extended, and/or branched from any suitable point along the existing circuit, including terminations at the CU.

andyp · Aug 29, 2024

SPECIAL LOCATION said:
All cables connected to the same protective device are part of the same circuit.

A radial circuit can be extended, and/or branched from any suitable point along the existing circuit, including terminations at the CU.

I like that answer. Thank you.

Murdoch · Aug 29, 2024

Does this circuit have RCD protection ?

andyp · Aug 29, 2024

Murdoch said:
Does this circuit have RCD protection ?

Yes, it's protected at the main CU

Fleeting · Aug 29, 2024

A type A RCD?

andyp · Aug 29, 2024

Fleeting said:
A type A RCD?

Good point. I'll have to check. I think it might be an AC on the main CU. There is also an RCD in the garage so that's something to check.

If I had to change the RCD would that come under as being notifiable? I'm trying to get may head around what is and isn't notifiable.

Thanks

Murdoch · Aug 29, 2024

andyp said:
Good point. I'll have to check. I think it might be an AC on the main CU. There is also an RCD in the garage so that's something to check.

If I had to change the RCD would that come under as being notifiable? I'm trying to get may head around what is and isn't notifiable.

Thanks

So 2 RCDs in series ?

SPECIAL LOCATION · Aug 29, 2024

andyp said:
If I had to change the RCD would that come under as being notifiable? I'm trying to get may head around what is and isn't notifiable.

Thanks

Some points you may want to consider are:-

If it was a like-for-like replacement due to the RCD being faulty then that is not notifiable..

If you had to replace a faulty AC type RCD it would be sensible to replace it with an equivalent rating Type A device.

If the overcurrent rating of the protective device, and the residual tripping current, and any time-delay characteristics of the RCD are identical, then other than the short length of additional cable you are adding, the overall circuit characteristics are pretty much unchanged..

You are not adding a new circuit which would be notifiable.. And work in a garage is not notifiable..

There is nothing within Approved Document P saying that replacing a protective device is notifiable..
https://assets.publishing.service.gov.uk/media/5a802da7ed915d74e622ceed/BR_PDF_AD_P_2013.pdf

If you are a member of a trades body able to self certify & notify part P work, then if in doubt you could easily notify any work that may not actually need notification..

But as various aspects of Part-P are a bit vague and open to debate... Unless you choose to use unauthorised logoed paperwork, it is very unlikely anyone would ever question or investigate the work you have done or pursue any legal action.

At the end of the day it is your call...

andyp · Aug 29, 2024

Murdoch said:
So 2 RCDs in series ?

The main CU in the house has 2 AC RCDs covering everything. Then the garage has its own RCCB (so yes in series)

andyp · Aug 29, 2024

SPECIAL LOCATION said:
Some points you may want to consider are:-

If it was a like-for-like replacement due to the RCD being faulty then that is not notifiable..

If you had to replace a faulty AC type RCD it would be sensible to replace it with an equivalent rating Type A device.

If the overcurrent rating of the protective device, and the residual tripping current, and any time-delay characteristics of the RCD are identical, then other than the short length of additional cable you are adding, the overall circuit characteristics are pretty much unchanged..

You are not adding a new circuit which would be notifiable.. And work in a garage is not notifiable..

There is nothing within Approved Document P saying that replacing a protective device is notifiable..
https://assets.publishing.service.gov.uk/media/5a802da7ed915d74e622ceed/BR_PDF_AD_P_2013.pdf

If you are a member of a trades body able to self certify & notify part P work, then if in doubt you could easily notify any work that may not actually need notification..

But as various aspects of Part-P are a bit vague and open to debate... Unless you choose to use unauthorised logoed paperwork, it is very unlikely anyone would ever question or investigate the work you have done or pursue any legal action.

At the end of the day it is your call...

Thats very good info. Thank you.

I'd like to get to the point of joining a trades body but still at the beginning here.
Thanks for your help.

SPECIAL LOCATION · Aug 29, 2024

andyp said:
Thats very good info. Thank you.

I'd like to get to the point of joining a trades body but still at the beginning here.
Thanks for your help.

I would guess that if you provided a Minor Works Certificate based on the model forms in BS7671 with a description of works something like..

"Replace faulty RCD and add one additional socket in garage to circuit number 'XYZ' from garage CU"
Include all relevant test results and serial number(s) of appropriate test meter(s)...

Then your back will be covered... Issue copy of certificate and invoice to customer...

As long as you have covered ALL of your costs then "Jobs-A-Good-Un"

Back to basics..
You are NOT doing a rewire..
You are NOT doing a CU change..
You are NOT altering Kitchen / Utility socket circuits..
It's a Garage.. NOT a regular inhabited room of a dwelling!!

So.. Just make sure that ALL work you do will not leave the installation more dangerous than before you started.

binky · Aug 30, 2024

your standard ring circuit puts 2 cables into one MCB, so spur off at the MCB if you like, it's still just a radial cct.

andyp · Sep 1, 2024

binky said:
your standard ring circuit puts 2 cables into one MCB, so spur off at the MCB if you like, it's still just a radial cct.

makes sense

mainline · Sep 19, 2024

SPECIAL LOCATION said:
You are NOT altering Kitchen / Utility socket circuits

Is a kitchen in England classed as a special location ?

SPECIAL LOCATION · Sep 19, 2024

mainline said:
Is a kitchen in England classed as a special location ?

No, but the question was about extending a 20A radial socket circuit.
Which would not normally be appropriate for a kitchen or a utility due to the typical loads in use.

mainline · Sep 19, 2024

You implied by your post that a kitchen was a special location but I’m not going to dwell on the point.

mainline · Sep 19, 2024

SPECIAL LOCATION said:
No, but the question was about extending a 20A radial socket circuit.
Which would not normally be appropriate for a kitchen or a utility due to the typical loads in use.

Nothing wrong with a well designed radial circuit/s in a kitchen .

SPECIAL LOCATION · Sep 19, 2024

mainline said:
You implied by your post that a kitchen was a special location but I’m not going to dwell on the point.

No I didn't. I suggested that a 20A radial is not a wise choice had it been a kitchen rather than a garage.

mainline said:
Nothing wrong with a well designed radial circuit/s in a kitchen .

Which has nothing to do with the OPs question regarding extending a 20amp radial in the garage.

Radial final circuit extend

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