Help with Wiring outdoor security light from a loft circuit?

liam548

liam548

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Hi all,

Hopefully a relatively basic question and answer but thought I'd ask anyway to check.

I have lighting in the loft, installed prior to us moving in and assume like most properties it runs from an upstairs light somewhere and therefore from the upstairs lighting ring.

I'm wanting to install an outdoor security light on the side of the house and realized the level of the loft floor is pretty much the perfect height give or take.

My plan is therefore to drill into the loft from outside and run cable and tap into the lighting cable junction as per the attached photo. It's not important for the outdoor light to be switched as it will be the PIR and dusk/dawn sensor type so can have mains 24/7.

Are there any issues with my plan? I assume I just use the two empty connectors in the box and link it to incoming Live feed as the loft lights have been?

Thank you in advance
 

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You don't need to use the empty terminals, just add into the L,N and E terminals already in use.
The bare wires should be sleeved in green/yellow.

A double pole switch really should be fitted, for the inevitable day when it breaks and stays on permanently or fills up with water and trips the whole circuit.
 
You can't assume what circuit the loft light is on ,you must establish that for certain. And before working on the circuit you must prove its dead with a meter or twin probe voltage tester.
The wiring is pretty much as you outlined ,permanent live ,neutral and earth from the JB. Ideally the circuit should be protected by an RCD ,and would be worthwhile having a double pole isolation switch on the supply to outside light to isolate it in the event it develops a fault / gets water ingress.

Edit ... SNAP !!
 
Thanks both for your replies. Yes I saw it had no earth sleeve when I opened it, (a pet hate of mine, just lazy not putting some on) so I will sort that at the same time.

I'll do as suggested then and agree, probably adding another switch to the outdoor light wiring would be better, no doubt one day when Im cursing due to the whole of the upstairs of the house being in darkness I'd be grateful for it. I'll fit a seperate switch and mark it up for outdoor light so its known to others and simply leave it on the "On position".

Terry, forgive me, whats JB mean??

Edit twigged, Junction Box. Cheers..
 
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What you could do whilst working on it is remove the JB, relocate the switch box 3 or 4 inches lower, and replace the single switch with a two gang, and have one for the loft lights and one for the outside light.

Bring the power cable, the cable to the loft light and a new cable run to the outside light all into the switch and make the connections there.
 
Colin Brenton said:
What you could do whilst working on it is remove the JB, relocate the switch box 3 or 4 inches lower, and replace the single switch with a two gang, and have one for the loft lights and one for the outside light.

Bring the power cable, the cable to the loft light and a new cable run to the outside light all into the switch and make the connections there.
Click to expand...

I think I may end up screwing the wiring up trying to do all that in a 2 gang socket, id end up with both turning on at same time when one should be off or vice versa haha. ;)

Was planning on maybe just getting another single switch and locating it slightly elsewhere, so if anyone else goes into the loft they don't inadvertently turn off the outside light without knowing...

That way I cant get anything wrong simply copying the existing wiring for the loft lights on the outdoor light.

Definitely no advantage using the 2 blank terminals in the JB other than space then?

Thanks for the suggestion though.

:)
 
TTC, yes, true enough, I hadn't thought of that.

Two DP switches on a dual box? ;)
 
Taylortwocities said:
We recommend that outside circuits can be isolated with a double pole switch. Wetness on the neutral causes as much trouble as on the line. A 2-gang light switch doesn’t provide isolation of the neutral.
Click to expand...

With a double pole switch it isolates both the live and neutral, correct? I.e would have more protection with regards to moisture on the neutral as you say.

Am I right in thinking for practical purposes for wiring it in there is no difference in installation from my end?

The other outdoor lights on the property all have their own single pole switches inside the house and in reality what's the difference here. If any of the other outdoor lights let moisture in then it would cause the same issue surely?
 
Last edited:
liam548 said:
I.e would have more protection with regards to moisture on the neutral as you say.
Click to expand...

The problem is that a Neutral to Earth Fault ( as in a damp or damaged lamp ) will cause the RCD to trip even though the switch in the Live supply to the lamp is switched OFF. The trip often happens when an appliance on a different circuit but protected by the RCD is switched ON. This makes one think the fault is in the appliance that was switched ON.
 
liam548 said:
The other outdoor lights on the property all have their own single pole switches inside the house and in reality what's the difference here. If any of the other outdoor lights let moisture in then it would cause the same issue surely?
Click to expand...
Yes they could cause the same issue. With new stuff, its best to anticipate issues rather than wait for disaster to strike. Its not such a problem sorting out a bit of water in a garden light, but I would rather have a DP switch to click in the loft instead of having to go two stories on a ladder to get to your leaking security light.
You are going to need a new switch anyways.
 
A DP switch for lights is easier - two terminals for the supply L&N, two other terminals for L&N to the light. It will also have at least one terminal for E

A light switch will require at least one additional terminal to connect the neutrals, the box may have an E terminal but plenty do not.

liam548 said:
Definitely no advantage using the 2 blank terminals in the JB other than space then?
Click to expand...
None. It's more work, as to use the empty terminals, short links would be needed from some of the existing terminals to the empty ones.
Otherwise, it's just 3 wires connecting to the existing 3 terminals, L top left, N top right, E centre right.
Centre left is the switched L for the existing light, nothing else needs to connect there.
 
flameport said:
A DP switch for lights is easier - two terminals for the supply L&N, two other terminals for L&N to the light. It will also have at least one terminal for E

A light switch will require at least one additional terminal to connect the neutrals, the box may have an E terminal but plenty do not.


None. It's more work, as to use the empty terminals, short links would be needed from some of the existing terminals to the empty ones.
Otherwise, it's just 3 wires connecting to the existing 3 terminals, L top left, N top right, E centre right.
Centre left is the switched L for the existing light, nothing else needs to connect there.
Click to expand...


Great help this thank you. I'll get a double pole switch then sounds better all round. Out of interest I asume if I was using a single pole switch Id be doing exactly the same as shown in the photo and also using the switched live terminal?


https://www.cef.co.uk/catalogue/products/643196-1-gang-45a-double-pole-switch-white


2 gang Synergy product chosen. Matches rest and seem decent quality.
 
Last edited:
flameport said:
A DP switch for lights is easier - two terminals for the supply L&N, two other terminals for L&N to the light. It will also have at least one terminal for E

A light switch will require at least one additional terminal to connect the neutrals, the box may have an E terminal but plenty do not.


None. It's more work, as to use the empty terminals, short links would be needed from some of the existing terminals to the empty ones.
Otherwise, it's just 3 wires connecting to the existing 3 terminals, L top left, N top right, E centre right.
Centre left is the switched L for the existing light, nothing else needs to connect there.
Click to expand...


Is there any requirement to stick a separate 5amp fuse in on this, or the fact its running on the house RCD will suffice with a double pole switch?
 
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