Can Anybody Make Sense of This Light For Me?

[paulp51d]

Hi,

I want to replace an outdoor PIR detection light with a simple non-detecting LED version.

When I removed the PIR light from its terminal block and started measuring voltages, I became confused. I was expecting some kind of turn-it-on and get 240V arrangement. Instead, I got strange voltages when the switch is turned OFF, and I have no idea what is going on. So, I am hoping somebody here can offer a clue?

The light is being replaced because it no longer works due to ingress of water, I think. That said, the wall-mounted terminal block, as shown in the picture, seems completely dry.

I have included pictures here and a diagram to show the voltages when the switch, inside the house, is turned OFF and ON.

Any thoughts will be appreciated.

Thanks.

 

[SUNRAY]

Yep, quite normal using a high impedance digital meter.

Do you simply want to know how to wire the new light? (grey = neutral, black = switched live for basic light, green yellow = earth). Or
Do you want to understand what is happening?

 

[EFLImpudence]

Don't really need to look at your chart:

Black is Switched Line(live) - Live when switch is on.
Brown is Permanent Line(live).
Grey is Neutral.
Green&yellow is Earth.

Don't worry about the other voltages.

 

[paulp51d]

First, thanks, as mostly I want to know how to wire the new light, and now I do. Second, though, I would like to know what is going on, as I have never measured these odd voltages before?

 

[Taylortwocities]

The “odd” voltages is because most basic meters are high impedance. This means they will display any random voltages that are on unterminated conductors. These are there through induction. Usually from adjacent cables.

 

[jj4091]

So it seems like it just the PIR that has failed. If you are going to fit a new one without that facility just rewire the existing fitting without the PIR in the circuit

 

[paulp51d]

OK, thanks everybody for the help. I now have the info I need to make the new connections, plus I have the explanation for the stray voltages. Thanks again.

Paul

 

[Murdochcat]

OK, thanks everybody for the help. I now have the info I need to make the new connections, plus I have the explanation for the stray voltages. Thanks again.

Paul

By the way it’s connected it looks like there is the ability to switch to manual on/off inside the house. What type of switch is inside ?

 

[SUNRAY]

By the way it’s connected it looks like there is the ability to switch to manual on/off inside the house. What type of switch is inside ?

This one