Decking LEDs run off outside Light

[Seb101]

Hi,

I'm considering installing some 12V LED floor level deck lights, they run off a 12V transformer.

They are suggested to be run from an outdoor socket, but I don't currently have an outdoor socket, however I do already have an existing outside light. Would it be acceptable to spur off this into an IP68 box mounted on the wall, put an inline RCD and the transformer in that box and then run a 12V cable down to the deck level for the lights?

If not - is there any other way this could be achieved without installing an outdoor socket?

Diagram below.

Cheers!

 

[Seb101]

The lighting circuit isn't RCD protected at the consumer unit, so it seemed like a good idea to put one on, but thinking about it, I'm not sure it is really protecting against anything, as a water ingress into the 12V LED units is unlikely to cause any type of electrical condition that would trip the RCD, if anything it would damage the transformer.

It has a flying lead that currently terminates in a moulded plug.

 

[SFK]

Seb,
I have put in Garden 12V lights (as DIYer) where I took from outside light (which is on a PIR).
As BanAll Sheds says above, I did not have an RCD in the outside box as all properly protected at Fuse Box.
I know not a direct answer to you question, but might be useful for you to know I did it in the following way:

1) You are using Decking Lights. Made a note of number needed and their Wattage to find total wattage (eg 10lights x 3W each = 30W)

2) Selected LED power supply from Amazon with search "LED Driver" and selected one that had a Wattage greater (say 25%) than that needed for the lights (so 10lights x 3W each = 30W x 125% = >38W)
https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=LED+driver&rh=i:aps,k:LED+driver

3) I selected a flat 12V Power Supply/Driver, and put on a Short Mains Cable, and put it into a water poof box with two Cable Gland Clamps in the bottom two holes, one for the Incoming Mains Cable from Outside light and one for the Outgoing 12V cable. Not sure if this could cause overheating for bigger wattage power supplys so keep eye on this. Drilled a 3mm hole in the Drain hole of water poof box to allow any condensation to exit.
http://www.screwfix.com/p/british-general-ip55-enclosure-grey-150-x-53-x-85mm/35121
http://www.screwfix.com/p/ip55-enclosure-grey-180-x-110-x-100mm/96153
http://www.screwfix.com/p/tower-male-comp-gland-black-20mm-pack-of-2/80851

3) My 12V Cable run was 22meters, so I was very conscious of Voltage drop with this site showing significant voltage drop for me when using 0.75mm2 cable. But I found that 1.5mm2 cable was difficult to get into the small connections of my 12V Power Supply/Driver, so I went with 0.75mm2 cable and crossed my fingers. For me the LEDs worked perfectly okay and I am happy with the brightness, but it should be noted that I cannot tell if they are significantly dimmer as I never made a comparison. And you might notice this more as you have a string of lights one after the other.
So I used 0.75mm2 Black 'rubber' cable as more durable and less noticeable on fence (where I attached it). For the 12V cable I did not use the Earth lead.
I also used this cable from the Light to Box for the 240V (see safetly note at end)
http://www.screwfix.com/search?search=Tough+Flexible+Cable
http://www.screwfix.com/p/tower-co-axial-cable-clip-7-0mm-black-pack-of-100/14161

4) Joining 12V Cable to lights. I looked at ebays "T cable connector" and decided that the following were too expensive for me (although the correct and proper things to use).
http://www.ebay.co.uk/sch/i.html?_o...onnector.TRS0&_nkw=T+cable+connector&_sacat=0
http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_nkw=IP66+box&_sop=12
I also considered IP55 junction boxes at £1.20 each and use two or three cable clamps for the cable.
http://www.toolstation.com/shop/Electrical/d190/IP55+Rated/sd3140
http://www.toolstation.com/search?searchstr=25329 80473 87759
But to save money (perhaps causing me issues later) I soldered the cables together at each junction and sealed it self amiglating tape.
http://www.lightingforgardens.com/garden-lighting-tips-cable-joint-kits
Note, sometimes you can join the cable inside the lights, removing this T junction issue.

5) Switches
To control the lights outside I used outdoor switches with the 12V cable going in and out using cable compression glads.
http://www.screwfix.com/p/bg-1-gang-2-way-single-pole-slim-weatherproof-switch/42402
http://www.screwfix.com/p/tower-male-comp-gland-black-20mm-pack-of-2/80851

5) Notes
Big issue.... you are messing around with both 240V and 12V. Make sure you keep them separate. Make sure you are not complacent when handling the 240V cable after you have been handling the 12V cable.
Don't do this if you are not in any way happy with handling electricity.
Is 240V power supply properly protected (Fuse / MCB / RCD etc)

sfk

 

[ban-all-sheds]

"water ingress into the 12V LED units is unlikely impossible to cause any type of electrical condition that would trip the RCD"

 

[Taylortwocities]

Nope, nothing received on this thread either. This is wonderful …

 

[Seb101]

Did the 240V side of the job last night after work. Decided to change from the original plan slightly so as to make the box more at a more serviceable height and hide one of the conduit runs behind the drainpipe. Also added some festoon lighting strung across the garden.

The black gland on the left of the box is where the 12V for the decking lights will come out.