Outdoor LED seciruty light needs extending


30 Jul 2019
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United Kingdom
Just going to buy a typical 30w LED security spotlight (off amazon) with PIR, mains power. But the cable isnt long enough so i need to extend it. but i dont know what cable i should get?

Ive seen a few different lights, some are 2 core, some are 3 core (according to the pictures). Is two core allowed? and does that affect which cable i should get?

I should add the join and extension will be inside (in a garage), not outside

Thanks for the advise.

Will be an easy job, but want to get the right cabling.




And thinking to use a join like this

They might be poor quality I dont know, but i cant find a reputable make, just unknown brands.
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The lower one is definitely Class 1 as it has 3 core cable fitted. To extend this you will obviously need 3 core. 1.0mm will be perfectly adequate for this one.

The upper one 'appears' to be 2 core with no earth. The description states it is metal so it should also have an earth lead in the cable.
The connection box appears to be suitable for what you want to do.
Thanks Conny, so I should double check if the upper one really is only 2 core, because i shouldn't get that it its only 2.
I assume you can use a 1.5mm or 2.5mm instead, if you had it handy?

Whats the best way to wire it into an existing garage circuit (garage has surface mounted sockets and cables, which i renewed, and i check the potential load and it was fine.
Should i take one of the mains cables that goes to a socket, put a junction box in and run it from there?
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Just going to buy a typical 30w LED security spotlight (off amazon)
I know it's tempting to use Amazon for the connivance (heck I use them myself for that reason), but it's important to be aware that they take no responsibility for products sold by third party sellers on their site. While nothing is perfect I'd say you are much less likely to get dangerous crap buying from the likes of Screwfix, CPC or an electrical wholesaler than you are buying from third party sellers on Amazon.

Ive seen a few different lights, some are 2 core, some are 3 core (according to the pictures). Is two core allowed?
Appliances are divided into classes.

Class 0: does not have an earth and is not single fault safe, generally forbidden in most western countries.
Class 1: relies on a protective earth for single fault safety.
Class 2: achieves "single fault" safety without a protective earth.

It's possible to design a metal cased appliance that meets class 2 requirements, but it requires a high level of attention to detail in the design, manufacturing and in some cases installation processes.

When you see things like a picture where the wires have the wrong colors and another picture (which does have the right colors, why are the two pictures inconsistent on color?!) referring to the neutral wire as the null wire it does not inspire confidence in the capabilities of the manufacturer to comply with standards.

and does that affect which cable i should get?
Not really. Any wiring that is fixed in place should always have an earth conductor, both because of requirements in BS7671 and because fixed wiring tends to outlive the equipment that it supplies.

Whats the best way to wire it into an existing garage circuit
We would need to know more details of how exactly the garage is wired to give detailed advice, but in general when running outside lighting off a socket circuit one would use a switched fused connection unit to provide isolation and overcurrent protection.
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HI Thanks for all the info.
I looked on screwfix, lots of ip44 rated, some ip65+ (it will get a lot of rain so ip44 not so good).
But CPC had lots i liked at a good price, so will definitely use them thanks
I have 5 double sockets (because there is also an attached brick shed) and a fluorescent strip light, with a switch for the light near the garage door
Dont laugh at the diagram!!
The garage circuit is on its own 16A fuse on the house main fuse box

These look ok to me maybe 20w would be ok, hard to tell,


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Hi No it doesnt, it was all like that when i moved in, should there be one?
The cable to the garage goes underground if that makes a difference
It would have been signed off about 6 years ago.
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If it was installed 6 years ago the sockets should have had RCD protection.

Can you post a picture of the consumer unit in your house?
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Hows that?


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Looks like everything has RCD protection (as would be expected for an install done at the date you said).

So back to your original question I would still recommend using a switched fused connection unit for connecting the light, you could argue that since the supply is only 16A the fuse isn't strictly necessary but I would still prefer to have overcurrent protection as close as possible to the normal operating current and a switched fused connection unit isn't significantly different in price from a double pole switch.

I always recommend double pole switching for outside lights in case water gets in and starts tripping your RCD.
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Thanks for checking that out and replying, so back to my other question "Whats (where?) is the best way to wire it into an existing garage circuit"
Can it T it off anywhere, or should it come from a socket? (with an inline switched fuse)
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You can branch off whereever is conviniant, but the terminals of one of the existing sockets are probably easiest.

For wiring on the supply side of the FCU I would try to stick with the same size/type of wiring as the existing, then on the load side of the FCU you can transition to smaller wiring protected by the fuse in the FCU.
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Socket would be easiest, but its not the closest lol. The light switch is the closes but i assume i cant use that.

So, use one of these (should the fuse be changed for a lower rated one?)
https://cpc.farnell.com/click/cl052/mc-13a-fused-spur-switched-neon/dp/PL14840?st=surface mounted fused switch

I'll use whatever size cable was already used in the garage, i think thats ok. Doesn't have to be smaller as far as i know.
Hopefully i can use the fused switch as the junction between my cable and the light's fixed 1m cable.
I enjoy doing this myself, just want to get it right.

I actually found a better diagram i did a couple of years ago (the original layout), when i could actually see in the garage better, but i added two sockets since then, off the first one.
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I would fit a 3A fuse.

I suspect the lightswitch only has permanent live and switched live, not neutral so it's probablly not possible to branch of there.
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Original layout


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