Confused about wires for external light fitting

s7ryf3925pivug

I am replacing an old floodlight which had an integrated motion sensor.

There is what I understand to be a two core and earth cable. It has a red wire, a black wire and a bare wire inside the same sheath. My understanding is that the black is neutral, the red live and the bare is earth.

What confuses me is that there is a second single brown wire in a separate sheath. Would this be for some switching mechanism - or what else if not?

The light hasn't worked while we've had the place. There is a switch near enough it that does nothing. So I assume that switch is intended to power it.

I'm trying to install a light that takes a normal live, neutral earth connection. Can I install that using the wires from the two core and earth cable and just cap the other cable and ignore it? Or is it not actually a compatible setup and I need to get an electrician in?

They are in an external garage that is thought to have been built in the 80s. The house was built in 1979.

Bruthal

It probably is a bypass switch to switch on the light without anything activating the sensor.

Now it might be the single wire that is the switched one, in which case the Live in the twin and earth would be connected into a connector and not used. Or it could be the L in the twin and earth that is the switched one.

This would have to be confirmed by testing with a multimeter, or else install the light as above and test it.

Circuit needs to be confirmed as de-energised as well before proceeding.

For a qualified and competent person, the above is all very simple. For a diy enthusiast, it might be a fair challenge.

s7ryf3925pivug

Thanks. I realised I still have the old light with the wires connected (I snipped them).

The main cable L and N wires are connected to the motion sensor.

The single live wire in is connected to the same hole as the live wire to the light. The other side of that is the live wire from the motion sensor.

So my understanding is that either one of those live wires could be used to provide power - right? Just cap the one not used? Just one will be permanently on and the other activated by the switch. (This is not a huge deal as it is a smart light.)

Bruthal

Richard Incalculable Prey wrote: »

Thanks. I realised I still have the old light with the wires connected (I snipped them).

The main cable L and N wires are connected to the motion sensor.

The single live wire in is connected to the same hole as the live wire to the light. The other side of that is the live wire from the motion sensor.

So my understanding is that either one of those live wires could be used to provide power - right? Just cap the one not used? Just one will be permanently on and the other activated by the switch. (This is not a huge deal as it is a smart light.)

Yes the switched one looks like it was the single wire. Twin and earth L was always on.

punisher5112

Red is live, black is neutral and earth obviously has no sheath on it.

If you could get a bit of cable and pull some earth sheath off that would be great.

Would you not put in another PIR along with it?

s7ryf3925pivug

It's the philips hue discover floodlight. I will use it with a PIR but it connects wirelessly and is powered by batteries.

Maewyn Succat

What colour are the wires at the switch?

punisher5112

Richard Incalculable Prey wrote: »

It's the philips hue discover floodlight. I will use it with a PIR but it connects wirelessly and is powered by batteries.

Ah get you, great lights.

Have hue everywhere.

s7ryf3925pivug

I'm not using the switch. Connected the 2 core and earth to the light and it is working. thanks.

s7ryf3925pivug

I replaced the other light on the same building. It didn't work. I was wondering if the extra live cable might be connected to that, so that the motion sensor would trigger both of them. Would that be plausible?

It is the far end of the building and the attic is very low (I'd have to assemble a platform to slide on my stomach) so getting over to see it up close inside is more trouble than it's probably worth.

Is it considered ok to put two wires in the same hole the way the old lamp was wired? If it is and if the wire was in fact connected to it then I could look to connect it to the switch that turns on the first light.

mcgragger

Richard Incalculable Prey wrote: »

I replaced the other light on the same building. It didn't work. I was wondering if the extra live cable might be connected to that, so that the motion sensor would trigger both of them. Would that be plausible?

It is the far end of the building and the attic is very low (I'd have to assemble a platform to slide on my stomach) so getting over to see it up close inside is more trouble than it's probably worth.

Is it considered ok to put two wires in the same hole the way the old lamp was wired? If it is and if the wire was in fact connected to it then I could look to connect it to the switch that turns on the first light.

Post a pic of the light terminal block and a pic of your cable.

I'll give you a guide.

The single cable could be a switch wire or a looped live to something else.
God knows in a 40yr old house. The previous owner could have been at anything.