wiring up a lighting photocell without a neutral wire?

[andyr123]

Hi, i want to wire up a photocell switch to my outdoor lights but want to wire it up to the 5amp light switch in the hall. in the old days I had a handy Smiths Timeguard light switch , the size of a normal UK wall light switch and it had a photocell in it and then a timer up to 8hours (so turned light on at dusk and programmable up to 8 hours) but that is discontinued now. From my memory (and I am not sure how it managed to do it) but the switch did not need a neutral wire to operate. You just simply used the existing live wires of the existing light switch (permanent live & switched live) . so my light switch in the hall just has the normal live wires and earth wire in the back box, no neutral wire of course. any ideas how I could wire up a photocell to it or what has replaced the smiths timeguard switch that does not need a neutral wire?

this was the timeguard switch (model numberZV210):

 

[Harry Bloomfield]

so my light switch in the hall just has the normal live wires and earth wire in the back box, no neutral wire of course. any ideas how I could wire up a photocell to it or what has replaced the smiths timeguard switch that does not need a neutral wire?

Unless the PIR is designed to work with no neutral, it cannot be done..

Those things which manage to work with no neutral, do so by charging a little internal battery, to run things. The battery is charged, when the switch is off, by passing a small current through the lamp circuit. They tend not to work as well with LED's.

 

[ETAF]

as far as i can see no neutral required, uses a battery

1 Gang Securiswitch Light Switch | Timeguard (ZV210N)

 

[ericmark]

as far as i can see no neutral required, uses a battery

The minimum lamp size is a problem.
I had the same problem, and this smart switch

cured it for me, but it needs a hub,

so unless using other smart devices it can work out expensive. PIR bulb

may help? Or just a smart bulb, they have dropped in price so much, last ones I got at £5 each, the problem is, one can spend more saving electric than the electric would cost, 10 watt bulb at 25p/kWh cost £22 a year left on 24/7, if I have got my maths right, so spending £35 on a switch seems OTT.

I use a smart bulb

the socket was put at top of steps for gardening, so put a lamp on a stork

with a smart bulb, and just unplug it when I need the socket. It is actually too bright with a 12 watt smart bulb to see to reverse with car's rear camera, so since smart, turned down to around 20% so only around 3 watt most of the time, which is enough.

 

[AndyPRK]

They don’t need neutral, but you must use an incandescent lamp.

Sadly no battery to charge.
The second the bulb fails or the power goes off, they loose their memory

 

[andyr123]

Unless the PIR is designed to work with no neutral, it cannot be done..

Those things which manage to work with no neutral, do so by charging a little internal battery, to run things. The battery is charged, when the switch is off, by passing a small current through the lamp circuit. They tend not to work as well with LED's.

as far as i can see no neutral required, uses a battery

1 Gang Securiswitch Light Switch | Timeguard (ZV210N)

Thats fascinating/like magic if thats the way it worked with a rechargeable battery inside , i mean how did it charge the battery in it without a neutral supply along with the live?

I have plenty of plug in digital timers in the house which have a battery in them , but the battery in them will only charge if there is a live and neutral present at the socket.

 

[ETAF]

it does not say anything about charging a battery

in the PDF data sheet it says

Battery 9V DC replaceable battery (Supplied)

 

[Harry Bloomfield]

Thats fascinating/like magic if thats the way it worked with a rechargeable battery inside , i mean how did it charge the battery in it without a neutral supply along with the live?

The switch, obviously, was in series with the load/lamp, so there was a voltage across the switch, when off. That voltage was stepped down, to charge the battery, when the lamp was switched off, to power the electronics when the light was on.

 

[andyr123]

it does not say anything about charging a battery

in the PDF data sheet it says

Ah right thank you - this is the new model then and this new model uses a replaceable 9v battery it makes sense now. my old timeguard switch didnt have a replaceable 9v battery in it ... so i presume it must have had a rechargeable one in it then, but the replacement ones these days have a normal alkaline 9v battery in it then

 

[AndyPRK]

I think they actually use the voltage drop across the triac to power the electronics