fitting two security lights

[wrathkeg]

Hi,

I am wanting to change my outdoor/security lights and am looking for some advice. The current situation is this: a cable comes out of the side of the house, through an airbrick, to a IR sensor. A cable then leaves that sensor to a light close by on the side of the house. Another cable leaves that light, and goes round the back to a floodlight (without its own sensor). So, anyone coming up the side of the house triggers both lights (side and back) from the one sensor.

This isn't ideal because when we come out of our back door, go to the bins, shed etc, the back light doesn't come on: the sensor is way round the side of the house, and even if I go down to dance in front of the sensor and then go to the back of the house, it only stays on a short time and then goes off. Would it be possible to use the existing wiring and just replace the side sensor+light, and the back light, each with a light and integral sensor? Or is a straight swap not recommended for some reason I haven't thought of?

I'm a DIYer, but II have changed plugs, light switches and light fittings, moved light fittings, etc, so I am not completely new to this kind of thing.

Best,

wrathkeg

 

[AshleyWilliams]

If putting in new lights its worth while starting from scratch.

Its difficult to explain without seeing the location of the lights on the building etc. But i would run a new cable from source. If the old lights are wired straight into the cosumer unit and is a big job to replace the cable. I would disconnect from both ends and cut back as far as possible. If they have a switch nside the property i would connect from there aslong as its in good condition. Simply run some 1.5 twin and earth to the first light then to the other. Trying to keep as much of the cable inside as possible.

The other option is to use a switched fused spur off one of the bedroom ring circuits and wire it off that.

Again its very difficult to explain on the internet. If your unsure i would call your local electrician.

A

 

[Chri5]

Convert the old sensor to be a external IP rated junction box with the LNE feed from inside the house, then from this box to the 1st light, then the existing cable between light 1 and 2 is contected to the LNE in at both lamps.

The result should be LNE available at both lights with the PIT / timer / switch function of both lights working to their own settings.

You should explore the cable on the inside and confirm it is either on the house lighting circuit, or if via a spur from the ring sockets is suitably fused at the spur.
Very important if you are changing the lamps to high load items than are already insitu, and the 1st point to check before you start.

 

[wrathkeg]

thanks, both, for responding. this is starting to sound like a bigger job than i thought.

it's hard to tell where the existing cable is coming from, as the airbrick which the cable passes through is concealed by cladding. The existing lights do have a switch inside the house, just by the back door.

AshleyWiliams: just to check, would you start over cos it's good practice i.e. so you know exactly what's what with the system?

 

[wrathkeg]

just checked and it looks like the outside lights are on the lighting circuit: switching the lighting circuit off at the CU stops the outside lights from coming on.

 

[Chri5]

So you now have the method of isolation.

New cable runs with new fittings are a 'nice' idea and prudent if the cable is aged, weathered etc- it will make the job cleaner since the j/box wouldn't be required.

So you have a switch wire for the switch extended through the house, this will terminate on a j/box upstairs that interupts the live at the LNE point in the house. Find that and re cable from there.

Cable will extend the switched live, neutral and earth to the 1st fitting and a second cable between fitting 1 and fitting 2.
TE 1.0 or 1.5mm needs to be used and you should keep external cable runs as short as possible, so route the cable via the loft or internal floor space. The cable isn't up to cold, hot, ice, uv so hence why you need to keep the majority of the route inside the house.

If you buy PIR security lamps with the facility, turning on/ off / on within a set period (normally 3 secs) will set the lamps to permanent on which could be handy for BBQ's and external events requiring the lighting to remain on rather than going off after the PIR time off, kicks in.

The lighting MCB should be rated at 6a or 6 x 230 = 1380w, do a quick add up of all lights on the circuit to make sure the added new (undisclosed load) lights don't overload the circuit.

 

[wrathkeg]

thanks for all this info. really helpful.

The lighting MCB should be rated at 6a or 6 x 230 = 1380w, do a quick add up of all lights on the circuit to make sure the added new (undisclosed load) lights don't overload the circuit.

is this as straightforward as totalling up the bulb wattages around the whole house? or is something more technical involved (there usually is )

 

[Chri5]

Turn off the light circuit and then every dead light needs to be counted as part of that circuit.

If you have LE lamps everywhere there is no issue, if you have GU10's everywhere (50w each) and a stack of multi lamp candelabra it might be an issue.

Are the new lamps going to be of the same or lesser wattage than the old ones ? because if so then it's safe to assume the circuit isn't going to be overloaded.

PS The thanks button is at the top

 

[AshleyWilliams]

Add up the wattage of the bulbs on that lighting circuit depending on the size of the house you may have two. So determine which lights are on that circuit. Add up the the wattage of all the bulbs. Then devide the total by 230 and you will get what current the circuit should draw.

A

 

[wrathkeg]

consider yourselves thanked......
I haven't decided on which lights to get, but it's unlikely to be more than the current set-up: one is 100W, and there is an insane halogen lamp too. seriously, it's enough to light a football pitch: I don't leave it on long in case it scorches the grass.... I haven't been up to it to have a look, but I'd guess it is in the 500W range.
Best,
wrathkeg