Power from Light Switch

[Owenzo]

Please Help!
I am attempting to install wardrobe lights in addition to my existing ceiling light. i would like to have them all operated from a 2 gang dimmer independent of each other

I have installed a 3 pin socket on top of the wardrobe to power the lights and wired this through to the light switch (2 gang dimmer)

Is it ok to power a socket from a light switch and how do you make the connection?
The ceiling light and dimmer work fine but when i try and wire the socket into the light switch the wardrobe lights dont work

 

[felix]

Where is the neutral connection for your new lights? You won't find one in the majority of light switches, only live and switched live. For a light to work properly you need the following connections:

Live -- switch -- light -- neutral

I suspect you have this:

Live ------ switch ------ light -- neutral
|-- switch -- new light --|

The new light cannot work this way.

 

[Owenzo]

Thanks for your reply
Interestingly I do have a neutral connection in the existing switch

I suspect the switch has been wired to allow for an additional switch to be added, so there is a neutral connection in the switch

I intend to draw power from the live connection in the existing circuit and connect this to the new circuit which i intend to connect to the existing neutral

Will this work?

 

[Big_Spark]

Sockets cannot be powered from lighting circuits.

Occasionally you may get 3A sockets attached, and if you use one of these you will be fine, but if you are proposing to use a standard socket faceplate you are in breach of the Regs for one, but also intoriducing something that could potentially be very dangerous.

Have you confirmed that the line you have at the switch is a neutral? Are you basing this assumption on the cable insulation being black? If so this is likely to be a switch return cable and not a neutral.

The only time neutrals are in switches is when they have been required for electronic switches or due to wiring method, and the neutrals are usually in connector blocks in the back of the switch and there will be more than one.

Ensure you know what you are looking at, there is potential danger if you get it wrong.

 

[mapj1]

I'm not so sure a socket off the lighting circuit is actually against any particular reg.
However, unless you are keen to be plunged into darkness, you need to be pretty D. sure that no one will ever make the error of plugging a full size 13a load into it, otherwise it is not a very good idea.
Often one is found in the loft feeding the TV pre-amp or similar, but I'd not recommend it unless there was no iother neat way of doing it.
I'd second the comments about the light switch neutral - if it goes to the switch, it is not neutral, it is returning the switched live.

 

[felix]

You can save yourself a lot of headaches with a simple test. Connect a standard light bulb between the live supply in the switch box and the one you think is neutral. If it lights up properly as soon as power is back on you have a good neutral. I don't recommend a meter for this test. You can get all sorts of false readings with a high impedance measurement. An on-load test is what you need.

 

[breezer]

its very doubtfull you have a neutral at the swicth, have a look in for refernce to see how its done

 

[Big_Spark]

Felix, your test will not work on a standard GLS lamp as the current flowing through it will cause it to operate if the other "live" is completing a circuit is someway.

If it's dangling free somewhere this test will tell you bugger all.

 

[Big_Spark]

I'm not so sure a socket off the lighting circuit is actually against any particular reg.

Try looking up Selection and Erection of Equipment Map...

Part 5, Chapter 51, Paragraph 511 Compliance with Standards.

Regulation 511-01-01:

Every item of equipment shall comply with the relevent requirments of the applicable British Standard, or Harmonised Standard appropriate to the intended use of that equipment.The edition of the Standard shall be the current edition, with those amendments pertaining at a date to be agreed by the parties to the contract concerned.

Alternatively, if equipment complying with a foriegn national standard based on an IEC standard is to be used, the designer or other person responsible for specifying shall verify that any differences between that standard and the correponding British standard will not result in a lesser degree of safety than that afforded by compliance with the British Standard.

Further to the above Regulation I would suggest that you look up regulation 512-02-01 concerning the current rating of devices. This regulation means that all installed devices must be specified with adherence to the operational characteristics of the protective device of that circuit.

This means that installing a 13A socket on a lighting circuit will exceed the design parameters of the protective device and also exceed the specified design parameters of the circuit.

Also, you might wish to read Regulation 512-05-01 and 512-06.


Should be some good bedtime reading Map

 

[mapj1]

But you could for devilment also read the same words to mean that a ring main is also inadequate, as there are enough potential 13A loads to operate the protective device.

I'd suggest that such an exception might be OK if the 13A socket is clearly positioned or marked so as to be not for use except for a lighting fitting or transformer (for example), in the same way that one in the ceiling for a projector is clearly not for hoovering from, and the max/min height rules should not apply. This then means the full load current of the circuit for the purpose of should not be taken as 13A, but the true load in that configuration.

This said, I'd still not recommend it if an alternative exists, such as a properly fed power socket, but if found I'd mark it as a non-standard circuit, rather than a breach of the regs per se. In this case I'd also advise against, just less emphatically.

 

[Owenzo]

Hi all and thanks for the replies
I am learning as i go along and i still have a healthy respect for electricity!

The switch has a set of brown wires which connect to the switchgear (C, L1, L2 etc)
A set of earth wires (green & yellow) and a set of blue wires which i assume is the neutral

The blue wires also have a connector attached to them which i assume is to enable a neutral connection if required ( i now understand that this will not complete the circuit anyway)

The new spotlight can be powered by doubling up on the connection to the main switch however i can only switch one light on at a time ideally i would like them to be independent of each other

There is noway anyone can plug a 13amp into the final setup (when i get it sorted) as it is on top of the wardrobe

 

[Big_Spark]

But you could for devilment also read the same words to mean that a ring main is also inadequate, as there are enough potential 13A loads to operate the protective device.

I'd suggest that such an exception might be OK if the 13A socket is clearly positioned or marked so as to be not for use except for a lighting fitting or transformer (for example), in the same way that one in the ceiling for a projector is clearly not for hoovering from, and the max/min height rules should not apply. This then means the full load current of the circuit for the purpose of should not be taken as 13A, but the true load in that configuration.

There is a flaw in your devilment, EACH individual socket does not exceed the current carrying capacity of the protective device, adding a 13A socket to a lighiting circuit means the socket can overload the breaker and possibly the cable, conseqently the two situations are nothing alike.

As for your second paragraph, this is what 3A, 5A sockets and Plug in roses are for. Suggesting for one minute that it is ok to put a 13A socket on a lighting circuit is sheer lunacy.

 

[Big_Spark]

Hi all and thanks for the replies
I am learning as i go along and i still have a healthy respect for electricity!

blue wires which i assume is the neutral

There is noway anyone can plug a 13amp into the final setup (when i get it sorted) as it is on top of the wardrobe

The Blue cores in a connector almost certainly ARE neutral if your description is accurate and as such could be used for extending power to a new light.

If you have a healthy respect for electricity, get the correct accessory (3A socket) and do the job properly. Putting a 13A socket on a lighting circuit IS a breach of the Regs, common sense, good practice and personally I think this type of action is one of the reason I advocate the banning of most DIY electrical work. (But lets not go there in this thread )

 

[Damocles]

As far as I can see the reg quoted means that the socket used must be capable of performing what is required of it. It is required to carry a maximum of 6A but is rated at 13A. So absolutely no problem.

On the other hand the reg would be broken if you took one of those 5A round pin sockets and connected it to a ring. It would then be required to carry 32A, which it very likely would not. Then again, if it had a built in 5A fuse limiting current draw it might be ok. Though the cable connections might not be designed big enough.....

 

[felix]

So you have a terminal block full of earths and another one full of blue wires which do sound like neutrals but what's this all about?

The new spotlight can be powered by doubling up on the connection to the main switch however i can only switch one light on at a time ideally i would like them to be independent of each other

Do you mean that when one is on the other is off? You have a double dimmer switch and you want independent control of two lights. This really ought to be possible. I think we need a much more detailed description of where all the brown wires go. Also, is this switch part of any 2-way switching setup?

FWL_Engineer wrote:

Felix, your test will not work on a standard GLS lamp as the current flowing through it will cause it to operate if the other "live" is completing a circuit is someway

Fair enough. A bulb without a true neutral connection can still light up. It will be a bit dim if the current has to go through some other load but would Owenzo spot this?

If it's dangling free somewhere this test will tell you b*****r all.

Now you've lost me.