install an outside light

15 Jan 2008
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United Kingdom
Hi, I want to install an outside light and wire into a 3 gang 2 way switch, which would replace the existing 2 gang 2 way switch installed at present. I do not have easy access to a live feed from an existing ceiling rose, so I am intending to fit an extra mcb to the consumer unit and use this solely for the benefit of the feed to outside light. The consumer unit is very closely situated to the required position of the outside light and would only require a short length of cable to make the connection, the same would apply for the switch cable from light fitting to switch. I would just like confirmation that what I am intending is feasible and how I need to wire up the new 3 gang 2 way switch (which is chrome with metal rocker switches). Thanks.
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as opposed to creating new circuit would it not be better to come from a suitable fcu if you cant access lights?
fused connection unit - taken from nearby plug socket fitted with appropriate size fuse to feed light (check wikki)
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I would just like confirmation that what I am intending is feasible
It would be much better to take the feed from the existing lighting MCB, otherwise you'll have 2 circuits at the switch to isolate for safe working in the future, which requires documentation, warning labels etc. (Just a thought though - is this just a normal light,or a high-wattage floodlight?)

and how I need to wire up the new 3 gang 2 way switch (which is chrome with metal rocker switches). Thanks.
Cable from CU to switch box. Either cut it there, and join the neutrals in a piece of choc-block, or carefully remove a section of sheath, leave the N untouched, and just cut the earth and live.

Lives into C & L1 of one of the switch gangs.

Earths (sleeved) into the terminal on the back box along with all the other earths, and the flylead to the faceplate.

Cable from switch box to light.
take a new feed from a new MCB and you`ll need to certify it to Part P- do it as an addition instead,

its effort versus cost as usual
Thanks for the replies guys.
I have since read on another post of the need to have a new mcb signed off, so I will not be going down that road. I do like the idea given by ban-all-sheds of taking a feed from the existing mcb. In reply to your question, the new light I am intending to fit will be no more than 100W. I have been reading your other instructions and apologies for my ignorance but I am a bit confused by "cable from cu to switch box". What is the switch box you refer to? Thanks.
I,m going to start from the begining and explain this as simply as I can.Does your existing 2G switch have Permanent L+N feed(Your permanent live will be the red wire in the terminal marked C(Common) on the switch which has only 2 wires going to it and probably operates your downstair hall light. If you have a permanent neutral it will be a black wire connected to some other black wires in a connector block.If you do have these firstly change the switch If there is enough slack on the cables do it 1 wire at a time eg remove C from old switch and put into corresponding C on new switch then L1 from old switch etc 'til you have changed the switch if your old switch was plastic you will have to run a flying earth lead from the existing earth terminal to the earth terminal on the back of the faceplate on your new chrome switch.Do all this with the power off obviously.At this stage I would put the power on and make sure the existing lights work as they did before.Put power back off. All being ok take a link from the C terminal of the switch with 2 wires going to it and put it into the terminal markedC(common) on the switch you have not used.Now bring the live neutral and earth from your new light and connect live into terminal L1 of the swich you have just connected the common link ,connect neutral into connector block with other neutrals and earth onto existing earth terminal with other earths(using sleeving where appropriate).Check all connections are tight.Screw switch onto back box, restore power and try.Hope all goes well!
I am not at home at present so cannot check wiring on switch, but from what I remember the switch that controls the downstairs hall light does have only 2 wires going to it but I do not have a permanent neutral as there were no black wires in a connector block. Does this make a difference to the instructions you gave me. Thanks.
Thanks Ban-all-sheds. I have followed your instructions and I now have a safely installed outside light. Your help was much appreciated. Barneysbal.

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