Best practice to add socket and light to understairs cupboard

[Geetar500]

Hello,

I wish to add a double socket and light to the understairs cupboard.

The CU is also in the cupboard. There is redundant 6A MCB with twin and earth attached from where I removed an old alarm system.

There is also easy rear access to a hallway socket which I believe is directly on the ring final circuit (two twin and earth cables going into it).

The light will be a 9w bulkhead light. I wish to use the double socket for charging a cordless vacuum cleaner (not sure what the draw on this would be, maybe 40w?) and running an ethernet switch (3w max).

My initial thoughts were to use the 6A MCB for the light (so if something trips the downstairs lighting I still have light in the cupboard) and then spur off the ring final for the double socket?

Although I think due to what I am intending to use it for, I could also run the socket off the 6A MCB and be well within safe load. Although I have read that is not best practice in case someone comes along and plugs two electric heaters into it or something?

Does that sound correct and safe?

 

[terryplumb]

Extend the ring to a new socket. Run a spur from the new socket to a switched fused connection unit to supply the light, using a 3 amp fuse.
No need to run a new circuit from the CU for one light ( which is notifiable to BC ,by the way )

 

[SUNRAY]

Extend the ring to a new socket. Run a spur from the new socket to a switched fused connection unit to supply the light, using a 3 amp fuse.
No need to run a new circuit from the CU for one light ( which is notifiable to BC ,by the way )

The 6A circuit exists, presumably to a FCU, in which case no notification is required to use it for a light.
I'd power the new socket from either the ring OR the 6A depending on which is the most convenient.

My initial thoughts were to use the 6A MCB for the light (so if something trips the downstairs lighting I still have light in the cupboard) and then spur off the ring final for the double socket?

My suggestion too

Although I think due to what I am intending to use it for, I could also run the socket off the 6A MCB and be well within safe load. Although I have read that is not best practice in case someone comes along and plugs two electric heaters into it or something?

Putting a dymo label on the socket "3A maximum" will reduce the chances of anything untoward happening to virtually zero.
There is only one person on this forum who thinks it's a problem.

 

[terryplumb]

The 6A circuit exists, presumably to a FCU, in which case no notification is required to use it for a light.

Apologies , missed the part of the original post regarding the cable still connected to the MCB.

 

[Adam_151]

The old alarm circuit might not be on RCD.

Your new socket must be on RCD, even these days the new light should be on RCD (I'm still not sure why we need that reg, but its been in book few years now)

 

[winston1]

My initial thoughts were to use the 6A MCB for the light (so if something trips the downstairs lighting I still have light in the cupboard) and then spur off the ring final for the double socket?

That is the best way of doing it.

 

[SUNRAY]

The old alarm circuit might not be on RCD.

Your new socket must be on RCD, even these days the new light should be on RCD (I'm still not sure why we need that reg, but its been in book few years now)

Unless I missed this bit, the light doesn't need to be RCD protected if the wiring is surface mounted.

 

[Adam_151]

Unless I missed this bit, the light doesn't need to be RCD protected if the wiring is surface mounted.

It changed with the 18th edition: 411.3.4 requires that in domestic premises, that cirucits suppling lights are RCD protected. Never understood why it was added, most of them would be so protected (for new work, replacement boards etc) due to concealed cables or suppling points in bathrooms. So that only leaves surface wired lighting cirucits without the need for it, so understairs light like this one, loft lighting, garage lighting, the ornamental column on the patio... but why the need to catch these cases that avoid the either criteria, is there some risk with domestic lighting that I've not seen.

 

[EFLImpudence]

I wondered the same.

You will note that 411.3.3 states that it is the socket-outlets that must have the additional protection of an RCD - fair enough.

However, 411.3.4 states that is the final circuits supplying luminaires which require it. No other appliances have such a stipulation. What is different about lighting?


It might simply be that the two were written by different people but that does not explain the situation.

 

[DetlefSchmitz]

Well, my thought is that lighting circuits are about the only circuits that it is easy to touch with fingers (if you are changing a lamp).

 

[Tigercubrider]

I’d use an LED light and a door switch.
it’s easy to leave a cupboard light on.

 

[plugwash]

It changed with the 18th edition

However it is worth noting that approved document P still says "Electrical installations should be designed and installed in accordance with BS 7671:2008 incorporating Amendment No 1:2011"

 

[Geetar500]

The old alarm circuit might not be on RCD.

Your new socket must be on RCD, even these days the new light should be on RCD (I'm still not sure why we need that reg, but its been in book few years now)

Good point, the alarm circuit is indeed not on the RCD protected side of the CU. It is on the other side with the upstairs/downstairs lighting and...outdoor sockets. However the outdoor sockets are RCD sockets so not sure if that met the requirements at the time?

 

[plugwash]

not sure if that met the requirements at the time?

There has been a collosal f*ckup with the standardisation which means RCD sockets are basically useless if you are following the letter of current standards.

But if the lights are on non-RCD then it would presumablly have been installed when the 16th edition was current and IIRC that didn't require any particular standards for RCDs, just that they met certain trip times.

 

[EFLImpudence]

There has been a collosal f*ckup with the standardisation which means RCD sockets are basically useless if you are following the letter of current standards.

(I think) that is down to a misreading of the wording.