Spur off a socket to feed a small lighting circuit

[Au5tin]

Alright all, just thinking about running a spur off a socket to feed a couple of lights on a two-way. Is this do-able if just run a 3/5 amp fused spur off the socket and run the cable in 1.5mm to the lights? I`d take it off the lights already in but that means a lot bigger ball ache!
Any ideas greatly appreciated

 

[Chri5]

Yes you can do as you posted.

I would say that lights via a non light circuit are 2nd best from a safety point of view.
The risk is that someone would turn off the light circuit and not realise that some lights still remain live due to feeding off a ring circuit.
They find out when there up the ladder changing a fitting...........

Note the work and leave details beside the CU if you ever move.

 

[ban-all-sheds]

The risk is that someone would turn off the light circuit and not realise that some lights still remain live due to feeding off a ring circuit AND not competently testing that it's safe to work on....

 

[Chri5]

AND not competently testing that it's safe to work on....

Which is something all DIYers do having isolated the main lighting circuit...... They have access to meters, volt sticks and sensible testing equipment ??

Or do they know nothing about safe isolation and would assume that isolation via a light circuit tagged MCB would isolate all the lights on that floor.

Hence why I flagged it up, and suggested noting the departure from standard lighting via light MCB at the CU.

 

[Taylortwocities]

As this will be new work, it is vital that the socket circuit that feeds the new lights will be RCD protected.

RCDs are not meant to replace basic protection but it will provide a degree of safety for the DIYer who doesn't practise safe isolation on this circuit.

 

[jangcy]

Hi
I would like to add one more question to this topic.
As people agreed that we can spur off light (circuit) from socket via switched FCU (or just FCU and then light switch), is it OK to do it other way as well?
I've got socket in shed. Now I would like to add FCU (max 5A) and connect two lights (both via light switch). One to light in shed (max 60W) and second to light outside shed (max 100W).

Shed circuit is RCBO protected in CU.

So in other worlds. Can I connect 2 lights to one FCU and each light will get own light switch. There is not too much room on wall and if I would need to add two switched FCU from shed junction box, my wall would looks like switch board in power station....

And one more thing:
If cable to socket is 2.5mm2, should cable to light be 1.5mm2 or cable between shed junction box and FCU-2.5mm2 and after FCU 1.5mm2 (or even 1.00mm2 if it's just to one light)?

Thank you

 

[Taylortwocities]

Cabling wise either of your two option is OK

But (there is always a but) it depends on what type of circuit and protective device is feeding that socket.

Is the socket circuit a ring (protected by a 32A CPD,)
or is it a radial protected by a 16A or 20A CPD?
Or is it a spur from a ring?

Cablewise, everything up to the FCU should be 2.5mm², after the FCU, with a 3or 5 amp fuse in, 1.0mm² will be fine.

 

[OwainDIYer]

Strictly speaking, option 1.

You can combine everything in 1 double faceplate if you use a gridswitch with a fuse and 2 switches. This assumes you don't need RCD protection. If you need RCD on the new wiring then an RCD+FCU is the way to go.

 

[JohnW2]

I would say that lights via a non light circuit are 2nd best from a safety point of view.
The risk is that someone would turn off the light circuit and not realise that some lights still remain live due to feeding off a ring circuit.
They find out when there up the ladder changing a fitting...........

True, but I would point out that a similar risk can arise when (as is 'usual') there is more than one lighting circuit (e.g. 'upstairs' and 'downstairs') in an installation. It is by no means unknown [I've certainly seen it done, perhaps in the name of complying with 314.1(i) ] to have at least one light run off the 'wrong' circuit - i.e. so that there is at least some light available upstairs if the 'upstairs lighting circuit' fails. That is obviously a similar potential trap for the unwary and underlines the need to confirm that a circuit is dead before working on it.

I have to say that, in addition to formal 'testing for dead', as a first line of defence I would usually switch on the light I wanted to work on prior to isolating the circuit, to give me the initial reassurance of seeing the light go off!

Kind Regards, John

 

[jangcy]

Socket in shed is on radial 16A MCB circuit in 2xRCD consumer unit(I've got consumer unit with rcbo like this one http://www.screwfix.com/p/wylex-10-way-high-integrity-consumer-unit-10-mcbs/66470) and this radial circuit just for a shed (and small porch at back yard where is also junction box and light via switched FCU) so it's not part of ring circuit or it's not a spur.

If future I would like to ask electrician to remove shed MCB from one of two RCDs C U and put it as separated 16A RCBO like this one
http://www.screwfix.com/p/legrand-16a-30ma-b-curve-rcbo/88363
so if something happen to the outside circuit I won't lose power to (for example) boiler, fridge or alarm-but that's something else....sorry for OT.

 

[Taylortwocities]

OK, so option 1 is the way to go.

 

[jangcy]

Thank you

 

[RMS]

The risk is that someone would turn off the light circuit and not realise that some lights still remain live due to feeding off a ring circuit.
They find out when there up the ladder changing a fitting...........

Surely the person is not competent to carry this work out if they fail to carry out safe isolation correctly. (proving dead and all that)