3 core & earth to PIR light

[jacky8018]

Hi, I have to replace an outside PIR light, a simple flood light type. The old one is a bit more sophisticated with lots of wire in the light itself. The incoming cable is 3 cores (Brown, Black and Grey) and earth but the bare earthing cable wasn't used before on the old PIR light.

I cannot figure out how the new one will fit in, it only has a
connector L/N/E but which core goes with which? I looked on the internet one guy suggested the following connection as the 3 cores give an override function but I am unsure how it works.

I wired

Brown to L(ive
Blade to E(arth)
Grey to N(eutral)

It seems to work when I have the switched turned on - override, BUT when I turned it off at the switch and hope the PIR will take over the on/off function, I note electrical shock on the metal body! Clearly what I did was not correct. Question

1) Is the wiring connection correct?
2) How to use the bare earth wire cable onto the switch?
3) Why do I feel the electrical shock on the body?

Please HELP!!

Answer to the forum and e-mail to [email protected]

Thank you in advance

 

[canduit]

I'm guessing where you said 'blade' you mean black? If you got a shock off the metal body then black is a live conductor. A test meter is required to determine which is line, neutral and earth, which is all that the fitting requires. The fourth wire, which may be a permanent or switched line, could be placed in a terminal block, covered with tape and tucked away. Are there instructions for us to view online?

 

[EFLImpudence]

Re-read OP and can't tell which from that what may be wrong.

 

[bernardgreen]

the three coloured cores are likely to be

1 Neutral
2 Permanent Live
3 Switched Live

To tell which is which will need test equipment.

The reason the bare earth conductor was not used on the previous lamp may be that that lamp was double insulated and therefore do not need an earth.

 

[SimonH2]

Just to add to the above, a lot of PIR lights - or all sensors if you use a separate sensor - have separate terminals for a permanent live, and a switched live.

The switched live connects to the light(s), and is normally live when the PIR is triggered. But you can have a separate switch which will power the switched live line so you can override the PIR manually - and it sounds like this is what you have.

From how you describe it, the case of the lamp is live when the switch is off - so I'd say it's most likely that the black is the permanent live. Is the replacement light a PIR light, or just a plain light ?

If it's just a plain light, then you'll probably need to connect the light to the brown - which is most likely the switched live from the override switch. That leaves grey to be the neutral (it should be sleeved blue), and if the fitting is metal, then you almost certainly need to earth it with the earth core of the cable (it's possible it's double insulated, but very unlikely).

If it's a PIR light then you'll need to decide how you want it to work. If you just use the permanent live then it'll just work as a PIR light. If you use the switched live then it'll work as a PIR light buy you can turn it off at the switch. Some PIRs have an override where if you switch it off-on very quickly it will stay on (either indefinitely or for some longer period) - the instructions should say if this is the case.

Alternatively, get a better unit that has both the supply and switched circuit available at the terminal block.


IMPORTANT The obvious thing to point out is that if you'd made a note of which wires connected to where before taking the old one off, there'd be no guessing. This is something to remember for the future - it's a lot easier sorting things out if you know how they used to be connected
Secondly, the only way to be certain of which wire is which is to either use test equipment (and know how to use it, and use it safely), or to look at the wiring at the other end of the cable (most likely behind the switch). So where I say "most likely" above, I really do mean "likely" and not "will be" - it's far from guaranteed.

 

[flameport]

The OP when presented with a cable containing 3 coloured cores and what they describe as a 'bare earth' has then proceeded to connect them in a completely random fashion, including connecting one of them to the clearly marked E terminal, totally ignoring what they have already stated to be the 'bare earth'.

Given such blatant stupidity and total disregard for even their own minimal knowledge of which wire does what, they should NOT attempt any electrical work again, to avoid killing themselves and others.

To answer their original questions:
1. No, it's completely wrong and DANGEROUS
2. FFS
3. Because in this instance you were lucky and the shock didn't kill you.

 

[CJM0045]

@SimonH2 - I have the same problem, I'm replacing an old PIR Floodlight with a new one from Homebase. The new floodlight has a fast fix plate so the terminals are fixed to the wall with the back plate and then the lamp is fixed to the backplate. There are only 3 terminals on the backplate Live, Neutral and Earth but the orignal light was connect to 4 terminals as I have a 3 core, (red, yellow, and blue), plus earth cable coming from the house. The original light has a switch inside so the PIR can be overridden. The original set up was (supply cable first to light terminals)

Red to Brown Cable,
Blue to Blue and White cables,
Yellow, to Red and White cables,
Earth to Earth.

From what you say I have to determine which of the two cables, red or yellow are the live or switched live. I can do that ok but what happens to the spare cable? Do I just blank it off or does it have to go somewhere else?

Sorry for my ignorance but we thought it was going to be easy replacing like with like and were a bit dismayed to find we were one terminal short. As the old light has disintigrated and has to be replaced, no going back now, we have to find a solution.

Thanks for any help

 

[EFLImpudence]

Red to Brown Cable,
Blue to Blue and White cables,
Yellow, to Red and White cables,
Earth to Earth.

From what you say I have to determine which of the two cables, red or yellow are the live or switched live.

It would appear to be the Red is permanent but you should never assume.
However, you may require the switched live so you can turn it off.

I can do that ok but what happens to the spare cable? Do I just blank it off or does it have to go somewhere else?

Put it in another connector and position safely.

You may be able to tell by looking in the switch.

Send a picture.


You cannot do electrical work without a voltage and continuity detector.

 

[SimonH2]

You would have the terminate the spare core safely - put a single way of "choc block" terminal strip on it and tuck it inside the terminal box.

Most likely red is permanent live, and yellow is switched live. You'd probably want to use the switched live as that will allow the inside switch to turn the light off. You could only override the PIR if it has one of those stupid "switch it off and on quickly" features that is a pain if your supply "flickers" a bit.

Better still, take that light back and get a better one with the extra terminal.

 

[CJM0045]

Thanks for your replies. I had thought to take it back but we've had it a long time. I might just keep it as a spare for somewhere else and get a new one which has a more conventional fixing. We've never come across this type of fixing before. On the face of it, it seemed a good idea! If there is an easy solution we might as well try that first as it's on the wall now.

There might just be enough room to put in a choc block to blank off the cable we don't need. However, the switch in the house turns the light on, not off. When the switch in the house is off, the light works on sensor, when the switch is on, the light works permanently. Does that make a difference? I know normally it's the other way round but this light was wired some years ago with two other outside lights professionally and the electrician did all of them that way. It is easier than messing around switching lights on and off to get them to stay on. The original and the new light have this 'fast switch it on and off' feature but , of course, we don't need to use it because of the way it was wired. There is also a switched fuse in the house which isolates this and another outside light, not sure if that complicates matters or not.

 

[SimonH2]

If you wire the light to the switched live, you'll have the switch working so you can turn the light off, but not force it on. If the light has an override function (typically switch it off and on again within a few seconds), then you could use the switch to activate that (flick it off and on again).

 

[CJM0045]

Thanks SimonH2. I think we'll try that, it's a solution. We have to have a qualified electrician in to finish a shower installation in a couple of months, so I'll see if he can get it back working as it was but no big deal if he can't, I think your solution will work. Failing that I'm going to go and buy a new light and steer clear of Homebase!

Thanks to you and EFLImpudence for all your help. I'll have a go at that tomorrow when it's light.

 

[dhutch]

The OP when presented with a cable containing 3 coloured cores and what they describe as a 'bare earth' has then proceeded to connect them in a completely random fashion, including connecting one of them to the clearly marked E terminal, totally ignoring what they have already stated to be the 'bare earth'.

Given such blatant stupidity and total disregard for even their own minimal knowledge of which wire does what, they should NOT attempt any electrical work again, to avoid killing themselves and others.

To answer their original questions:
1. No, it's completely wrong and DANGEROUS
2. FFS
3. Because in this instance you were lucky and the shock didn't kill you.

You cant write it can you!