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How do I wire a switch to a PIR light?

Discussion in 'Electrics UK' started by BM12, 18 Aug 2012.

  1. BM12

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    Hi,

    I'm a newbie here and am currently trying to wire in a new exterior PIR light but am a little confused as to how to wire in a switch.

    There is no existing wiring so I have so far used this very helpful guide
    (http://www.diynot.com/pages/el/el032.php#a0) to run a new wire from the exterior PIR light to an existing rose that is located on the entrance porch. I put a the live of the new PIR light into the loop of the rose and the neutral of the new PIR light into the two terminal block of the rose.

    Now the existing porch rose has a single switch, but to keep things neat and tidy, i intend on changing this switch to a double gang switch and make one of these switches independently control the PIR light. Now the PIR light doesn't have as many terminals as a rose so i'm confused as to how the wires of the switch connect to the PIR light. The PIR light simply has L, N Earth and a LS.

    Appreciate if someone can help shed some light into this (no pun intended :))
     
  2. pjcomp

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    First up, the two-terminal block in a ceiling rose is usually the switched live, not the neutral, so you could have a problem there.

    Second, just adding a second switch won't make the light switchable - there has to be a dedicated link between the switch and the light that is being switched.

    From the sound of what you've done the best result will be absolutely nothing - worst will be a loud bang and a puff of smoke.

    PJ
     
  3. BM12

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    Thanks for your reply. Sorry I meant its connected to the neutral three terminal block and not the switched live two terminal block. The live wire is then connected to the central loop terminal block (along with the other live wires).

    The two terminal block is indeed switched. I haven't turned the power back on at the consumer unit, but believe that the way it is connected at the moment will just power the PIR light directly from the mains. I need to wire in a switch.

    What I meant is that I will fit a 2 gang switch where one gang will the porch rose light as it is currently connected to a single gang switch. I then need to work out how to wire/link the second switch to control the newly wired PIR light - which is where im stuck at now and need a bit of help/guidance?

    Please do let me know if I have so far, done anything wrong.
     
  4. securespark

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    You need a 3 core to the PIR light.

    Live & Neutral feed like at present, plus a switchwire going to the live of the lamp.

    The switch shorts the permanent live to this switch wire, thus turning the lamp on independently of the PIR.

    What size is the lamp?

    If bigger than 150W, it needs to go on a power circuit really.
     
  5. BM12

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    I am still a bit confused. Would you be able to clarify?

    Having thought about it and created this diagram, I think i've now got it right, but just want to make sure i'm not creating a problem here. For ease I just shown where the cores are (earthing left out). Can someone confirm if this is OK?

    [​IMG]

    I'm wondering whether it will be easier to leave the dual gang switch off and just leave it wired directly to the mains as it is, but just create a break in the live and wire one end coming from the lamp and the other end coming from the rose loop to a seperate inline slim switch. This would keep the wiring cleaner, as some areas will have to use conduit and only want to use a minimal amount of it. Is it ok to do this?

    Appreciate all the help so far :D
     
  6. securespark

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    The way you've configured it in the diagram, the switch for the PIR light will just turn off power to the fitting when off and apply power to it when on.

    This is fine if your PIR light is the type that can be triggered to stay on all the time if you flip the switch.

    If not, you need a third core to the PIR light which connects to the lamp live (ie the wire that is on when the passive is triggered) and this wire goes to the switch with a permanent live to feed it.

    When the switch is on, the light is on, independent of the PIR (manually on).


    When the switch is off, the fitting will revert to automatic operation.
     
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  7. Mursal

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    I would connect the PIR L to the connection block (constant Live) and the wire from the switch that was going to PIR L connect it to LS on the PIR
     
  8. securespark

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    Or for that matter connect the two wire showing at the switch in the diagram together on the Common & take a third conductor to SL on the PIR light.

    But it would be good to have an isolator.
     
  9. BM12

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    Thanks for the replies and help - appreciated.

    Just a bit of info about the lantern - it is a motion detector lantern and is designed to switch on at night when motion is detected. During the day the photocell sensor saves electricity by deactivating the lantern. This is the exact light i'm fitting: http://www.argos.co.uk/static/Product/partNumber/9385331/Trail/searchtext>PIR+LANTERN.htm

    The reason for me to install the switch is simply to have the option to switch it off completely. When the switch is on, I simply want it to trigger only when motion is detected, not stay permanently on.

    I think it will be easier (wiring wise) for me to run just one twin core and earth cable between the rose and the PIR light, and just create a break in the Live and fit a architrave type slimline single gang switch between the live coming from the rose loop and live connected to the switch. Is this going to achieve what I want it to do without causing problems? I have revised my diagram below to clarify exactly how i intend to connect. Where the break is show is where i will install the architrave switch.

    [​IMG]

    As for earth, there is a bundle of earths that are on the rose. If I wrap one end to these and connect the other end to the new lamps earth terminal am I good to go? This does mean that an earth won't be at the switch. But as I will only be breaking the live wire at the switch point (not the earth or neutral) will this be fine. It is going to be a plastic switch.

    Securespark you mentioned the size of the lamp. Its not clearly stated but in the manual it states. Could you also tell me if this is ok.

    Lighting load: 60w incandescent lamps or 20W energy saving lamp.

    Additional lighting load: 500w (i assume this is if i run another lamp off this, which I won't)

    Power requirement: AC 220/240v / 50Hz


    Finally, I know that the type of wire you use is also important for the load.

    I have a large reel of grey twin and earth 2.5mm2 wire from when I did a underfloor heating install and thick this is too thick for this lamp (I think the recommended is 1.5mm2). I know that you must not use a thinner wire but is it perfectly fine to use a thicker wire?

    Thanks for your help and sorry for all the questions. I just want to double ensure I won't cause a hazard or anything to blow by doing this.
     
  10. BM12

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    Can anyone confirm if what I intend to do on my previous post will be safe and ok to achieve what i want it to do?

    Need to get this wired in now but just want to ensure all will be ok.
     
  11. ban-all-sheds

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    Under what circumstances would you want to do that? What would remind you to turn it back on?


    Yes there will - you'll be using twin and earth, as you said.


    You'll have to cut the earth wire to be able to put sleeving on it.


    As long as it will fit it will be fine, but the lamp terminals might not take it, the rose probably won't, and it'll be cramped at the architrave switch.
     
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  12. BM12

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    I just want to keep the option of completely switching it off, as the other PIR's in my house are wired to be. Most of the time they will be on all the time, but its just in case. Would I achieve this by how I intend to wire this?

    So at the switch I can simply cut the single twin and earth wire running between the rose and the PIR light, connect the two LIVE ends to the switch and connect the two neutrals together and the two Earths together using a connection block behind the switch and that should be fine?
     
  13. ban-all-sheds

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    I'd advise against using a normal single-pole switch - outside lights have been known to have problems with water penetration, leading to RCDs tripping, so it can be useful to isolate the neutral as well. Use a double-pole switch.

    If you're strapped for space, the Click Minigrid range from Scolmore has a single-module architrave faceplate, and you can put a DP switch module into that.
     
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