Garage extra socket

RobertPW · 13 May 2020

Hi there

Yesterday I installed an electric garage door which I am currently running from an extension lead.

My garage has a small consumer unit with no spare mcbs. From the consumer unit are 1 double socket on a 16amp mcb and 2x 6amp mcbs running internal and external lights.

I now need to add an extra socket to power the garage door. I know I could spur off the existing socket, 12 meters away, but seems excessive on cable. There are other options I know, but my questions are these (to come up with the most efficient way, in terms of cable and time whilst still being safe)...

1. Could I go from the consumer unit to one FSU then run a cable from the FSU to each socket. ie. the FSU would have two outputs rather than daisy chaining the two sockets.

Socket---------------FSU---------------Socket
l
l
Consumer Unit

2. I think I know the answer is no, but could I just run the new socket to the existing MCB, giving me two outputs from one MCB?

Thanks in advance

Rob

EFLImpudence · 13 May 2020

What is an FSU?

Do you mean JB?

Can you not connect the new cable to the consumer unit?

Taylortwocities · 14 May 2020

Yes you can run the new socket from the 16A MCB as well as the existing socket.

securespark · 14 May 2020

Fused Spur Unit?
If the circuit is protected by a 16A device, you can do away with the fused connection unit.
If the CU is nearest to the door, then as TTC suggests, you can connect to the circuit at the terminals in the CU.

SFK · 14 May 2020

As the circuit is already protected by a 16A device I would use another socket to make up the junction:

Socket---------------Socket---------------Socket
l
l
Consumer Unit

Note that I have hard wired my garage door (as a DIYer) using a fused switched flex out socket like this one. Meant that I could take out the fuse when on holiday if I wanted to make it a bit harder for anyone to electrically operate garage the door.

https://www.screwfix.com/p/13a-switched-metal-clad-fused-spur-flex-outlet-with-white-inserts/66454

SFK

Taylortwocities · 14 May 2020

From the OP’s post I rather think that doesn’t meet his cable-saving ambitions!

RobertPW · 14 May 2020

Thanks for your input everyone. I did consider that an FSU was only doing the same job as the mcb. I’ve been advised 2 cables in one mcb is not best practice so will go from consumer unit to a new socket next to the consumer unit, then there is enough cable to go from the new socket to the existing socket.

Thank you

RF Lighting · 14 May 2020

You have been advised incorrectly.

Two cables in one MCB is absolutely a standard circuit arrangement.

EFLImpudence · 14 May 2020

As said - you have been advised incorrectly -

and very strangely - as the vast majority of socket circuits in the UK do have two cables in one MCB.

flameport · 14 May 2020

Should be 1 MCB = 1 circuit.
2 cables from a ring is still the same circuit.
2 cables for two separate radials is not.

EFLImpudence · 14 May 2020

flameport said:
Should be 1 MCB = 1 circuit.

By BS 7671 definition it can be nothing else.

2 cables from a ring is still the same circuit.
2 cables for two separate radials is not.

Yes, it is - two radials on the same circuit or one radial and one spur/branch; whatever you want to call them

The OP was told two cables in one MCB is not allowed - clearly wrong whatever the arrangement.

RobertPW · 14 May 2020

Would 2 cables, each feeding a separate socket not be classed as two radials and therefore not okay. This is the context in which I have been not advised to have two cables in one MCB. Sorry if I haven’t explained this clearly.

Regards

Rob

Taylortwocities · 14 May 2020

Ok, here’s the way.

one wire from the MCB, about 4” long
Terminate it in a 3-way Wago
Connect the two cables to the Wago. Voila! One radial with two branches, One conductor in MCB. completely within regs

BUT POINTLESS ADDITIONAL JOINT.

DetlefSchmitz · 14 May 2020

RobertPW said:
Would 2 cables, each feeding a separate socket not be classed as two radials and therefore not okay. This is the context in which I have been not advised to have two cables in one MCB. Sorry if I haven’t explained this clearly.

No it wouldn't. Ask whoever says this to quote you the regulation number.

In fact it is even permitted to have a spur from the MCB of a ring final, which results in three cables from the MCB.

Too many people make up rules as they go along, to sound knowledgeable.

AndyPRK · 14 May 2020

Think the aim in a house is not to connect 2 radial branches, in say different rooms to one MCB, so under failure conditions you don’t loose lots of power.

However for a garage with 2 sockets it’s not as issue

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Garage extra socket

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