Additional Sockets in Garage

[Matt_85]

Hey folks

Bit of pre-info, we have a new build, 2 years old with a main CU sending power to our attached garage via a 32A breaker.

In the garage there is a secondary CU which bizarrely has a 63A RCD main breaker with two supply breakers being 6A for lights & 16A for sockets.

Sockets wise there is a double for anything & a single on the roof joists for the garage door motor.

There is also an alarm panel which has a fused spur at 2A for protection and this is wired into the hot side of the 63A garage CU main breaker retaining power even when the breaker is off or the RCD is tripped.

The wiring layout is also radial.

My question is, after weeks of struggling to find a sparky to entertain the job (were guessing its to small a job, but after 27 successfully made contacts, they have all either refused the work, not turned up, or strangely turned up & then not quoted) is that I dont believe im legally allowed to add a ring main to the garage CU. However I need my 2 available sockets (not the single on the roof) to turn into 9 sockets (Not 9 doubles) to power what I plan to put in the garage (gym equipment, PC, fans & screens, total draw at 13.74A).

So, Q1, can I spur off the existing double socket to a 13A FCU followed by 4 double sockets. Total cable length would be 3m using 2.5 TE. And am I right in believing that is not notifiable work ?

And Q2, can I isolate the garage CU by the 32A breaker in the main home CU and remove the garage CU from the blockwork & refit once the room has been plastered. Naturally this means removing the front cover to get access to the mounting hardware.

Q3, Is the Alarm being wired into the hotside of the main breaker typical installation procedure ?

Cheers for any help in advance

 

[Matt_85]

Edit - I Should add that I know the extra socket question gets asked frequently and by searching it would appear this is an OK way to proceed. I mainly ask due to the volume of sockets being used (Not the the current draw will be significantly higher) and Q2 & Q3 being harder to find answers for.

 

[EFLImpudence]

In the garage there is a secondary CU which bizarrely has a 63A RCD main breaker with two supply breakers being 6A for lights & 16A for sockets.

The 63A is irrelevant (as long as it is more than the total load); it is the 30mA that is important.

The wiring layout is also radial.
I dont believe im legally allowed to add a ring main to the garage CU.

All the law says is that you must ensure the safety of your work.
You do not need a ring.

However I need my 2 available sockets (not the single on the roof) to turn into 9 sockets (Not 9 doubles) to power what I plan to put in the garage (gym equipment, PC, fans & screens, total draw at 13.74A).

Then just extend the radial.

So, Q1, can I spur off the existing double socket to a 13A FCU followed by 4 double sockets.

Yes but you don't need the FCU; you have a 16A MCB.

Total cable length would be 3m using 2.5 TE. And am I right in believing that is not notifiable work ?

It is not notifiable work.

And Q2, can I isolate the garage CU by the 32A breaker in the main home CU and remove the garage CU from the blockwork & refit once the room has been plastered. Naturally this means removing the front cover to get access to the mounting hardware.

Yes, but the breaker will not disconnect the Neutral nor the Earth.

Q3, Is the Alarm being wired into the hotside of the main breaker typical installation procedure ?

I doubt it is typical but it is alright.

Americans call it hot; we call it the supply or feed or in - nothing really specific.

 

[Matt_85]

The 63A is irrelevant (as long as it is more than the total load); it is the 30mA that is important.


All the law says is that you must ensure the safety of your work.
You do not need a ring.


Then just extend the radial.


Yes but you don't need the FCU; you have a 16A MCB.


It is not notifiable work.


Yes, but the breaker will not disconnect the Neutral nor the Earth.


I doubt it is typical but it is alright.

Americans call it hot; we call it the supply or feed or in - nothing really specific.

Thanks EFL, wonderful advice.

Regarding the installation of a ring, I didnt mean as such that its not legal to install one, but more so that I myself am not allowed to install a new ring circuit from scratch.

Extend is what I will do , if its currently using 4mm TE, does that have to continue or can it change. I only ask this as I have about 20m of 2.5 TE from another job a while ago but dont mind buying 4mm obviously.

Good to know no FCU is needed. Ive seen this mentioned before when paired with a 16A MCB. I think what threw me on this is that Reg 433.1 and specifically, the examples given on page 506 of the 18th show two versions, one using a 20A breaker & a 32A breaker. The 32A matching my main CU power supply to the garage pushed me over to that example which then specified either 1 socket without FCU, or multiple with FCU & taking diversity into account.

In terms of disconnecting the N&E, will the main isolator prior to my main CU (post meter) be more suitable for isolation in this case ?

Thanks

 

[EFLImpudence]

Regarding the installation of a ring, I didnt mean as such that its not legal to install one, but more so that I myself am not allowed to install a new ring circuit from scratch.

It depends what you mean by 'from scratch'
It still wouldn't necessarily be classed as a 'new circuit' as a circuit is all the equipment protected by the same device(MCB).
You are of course able to force the Local Authority to take your couple of hundred pounds if you want to.

Extend is what I will do , if its currently using 4mm TE, does that have to continue or can it change. I only ask this as I have about 20m of 2.5 TE from another job a while ago but dont mind buying 4mm obviously.

Extremely unlikely to be 4mm².
Either way, use your 2.5mm².
1.5mm² (20A) would do for 16A circuit.

Good to know no FCU is needed. Ive seen this mentioned before when paired with a 16A MCB. I think what threw me on this is that Reg 433.1 and specifically, the examples given on page 506 of the 18th show two versions, one using a 20A breaker & a 32A breaker. The 32A matching my main CU power supply to the garage pushed me over to that example which then specified either 1 socket without FCU, or multiple with FCU & taking diversity into account.

Yes, but you have a 16A in the garage and it is not a ring.
Plus, the examples only show using 2.5mm² or 1.5mm² cable; should you use 4mm² the FCU would not be needed anyway.

In terms of disconnecting the N&E, will the main isolator prior to my main CU (post meter) be more suitable for isolation in this case ?

It would be better.
It just depends on where the CU will be during the plastering.

 

[Matt_85]

I'd probably remove it and put it up on the ceiling joists out the way until all the studding is up then bring it back down just before fitting the board it will sit infront of.

It's currently shoulder height but I'd like to coil up a meter of it and fit the CU into the upper corner where wall meets ceiling.

I'll give the LA a miss on this occasion then, theyve had enough in council tax this year from me lol.

 

[EFLImpudence]