# Forum Home Renovation Lighting  stange wiring of sensor light .. please explain?

## davegol

Just wondering if this is normal? Sparky wired 4 halogens in the carport to a sensor, but when I turn the switch on, the sensor doesn't seem to be included - lights are ON all the time. When I turn the switch off, the light appears to go into sensor mode and works as expected. Is that normal? I've never seen a sensor light wired up that way ?!?

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## Ashore

It depends on the type of sensor, usually have a time delay in the system 
You can switch off and nothing works
Switch on and the lights stay on 
Switch off and on again in 10 seconds ( or what ever the time delay is set at ) and the lights work as a sensor
or can be the reverse swithc off and don't switch on till after whatever the time delay is and you go into sensor mode 
Yours appears incorrect as when switched off it is in sensor mode, switching off should isolate the swstem for changing lamps etc.

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## davegol

yep that's what I thought - it's incorrectly wired because you can't isolate the system to change a globe. Pretty sure that's not allowed.

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## Bruiser

Sounds ok to me.  Switch it on/off/on/off - if the lights turn on/off, then you have your isolation point. 
Switch off for 10s, then turn on.  It should be in 'sensor mode'.   
Switch off/on quickly - now it's on, per light switch. 
Switch off for 10s, then turn on.  Back to sensor mode.  The light will come on for however long the sensor timer is set when you do this.

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## davegol

I think you misunderstand .. or I miscommunicated  :Biggrin:   
Switch it ON and the lights stay on permanently (sensor seems to be bypassed) 
Switch it OFF (and leave it OFF) and the lights appear to be in sensor mode and if someone walks past, they'll switch ON!  
There doesn't appear to be any way to switch it OFF for sure. 
That's not right .. I think.

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## Bruiser

Agree - OFF should mean OFF.  Ask your sparky or, if you need help here, try to get a part number for the sensor.  It's not out of the question, but it is WHACKY!

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## LinesElectrical

Depends on what you want really I often wire them up like that especially in garages or porches. 
You have an isolator it's called the circuit breaker. 
The theory is its a security light you want it to come on at night and not accidentally be turned off so when you come home at night it doesn't work but it can also be bypassed for when your expecting somebody like the pizza guy.

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## davegol

thanks LinesElectrical.
I was just surprised as I'd never seen it done that way. It makes good sense though. So now I have to keep all my switches off, so that the sensors are on  :Smilie:

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## Bruiser

Lines,
Do you just wire from the breaker, then put the switch across the relay contacts?  So the foregoing ON/OFF discussion would apply, to the breaker?

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## SparkyTom

As Lines said, this method of wiring is normal and common. It's how I'm instructed to wire all sensor controlled lights on new houses. I'm not good with explanations, but I'll try my best to explain the options. 
We refer to a sensor as being wired either in parallel or in series with the light fittings. In your case, the lights are wired in parallel with the sensor, meaning the sensor is always receiving power. The light switch will act as a master "on" switch when switched on, but there is no master "off" for those lights other than the lighting circuit breaker. 
If the sensor is wired in series, then having the switch off leaves the lighting and sensor de-energised. Having the switch on will energise the sensor, not the lights directly. So you now have a master "off" switch, but no master "on" (the lights will come on if the switch is on AND the sensor is set off, but there's no way to leave them permanently on). Some sensors do have control circuits that will let you leave the lights on if you do something like switch the light off then on quickly. If you would prefer this setup, call your sparky back and it will most likely be a case of him just having to re-terminate a couple of wires behind the switchplate. 
If you want full control, another alternative I have seen is having a "triple throw" switch - a switch with 3 positions, rather than the usual 2 "on" and "off" positions. This can be wired in a way where you can switch the lights to be on, off, or sensor controlled. I imagine the switch mechanism costs a bit more, I'm not sure, but it likely wouldn't require any extra wiring (depending on how your sparky ran his wiring). 
The way yours is wired is often the preferred option. If people get a sensor installed, they want it to work, not to be left switched off all the time accidentally. Depends on personal preference and what sort of area/situation it's used in. Hope this helps

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## davegol

thanks for the explanation. 
I've never seen it done that way, but probably because all the sensor lights I've ever dealt with were wired after the fact, so the switch was the master for the sensor. 
anyway .. I'm happy with it the way it is - it's better actually. just didn't know it was legal.. happy to find that it is!

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