Electronic timer for outside light

[Nintendofan]

I have an outside light controlled by a normal plate switch in the porch, I have a neutral at the switch.

I want to replace the plate switch for an electronic timer, something like this http://www.toolstation.com/shop/Ele...ectronic Wall Switch Timer/d190/sd2660/p16578 the trouble is it says it will only control a minimum load of 40W. The light I want it to control is an egergy saving lamp (think its 18W)

I've looked at a few different timers and all the ones I've seen have a minimum switching current, why is this? surely it's just acting as a switch? any suggestions?

 

[bernardgreen]

The Greenbrook T40S does not require a Neutral, it takes its power by allowing a small current to flow through the load ( the lamp ) back to Neutral.

Hence there is a minimum wattage for the lamp to (a) ensure sufficient current can flow through it and (b) that the lamp will not glow on the small amount of current flowing when the switch is OFF

 

[Nintendofan]

The Greenbrook T40S does not require a Neutral, it takes its power by allowing a small current to flow through the load ( the lamp ) back to Neutral.

Hence there is a minimum wattage for the lamp to (a) ensure sufficient current can flow through it and (b) that the lamp will not glow on the small amount of current flowing when the switch is OFF

So are there any timers that will fit on a standard 1 gang backbox but have no minimum operating current that you know of?

edit: just found this http://www.tlc-direct.co.uk/Product...=adwords&kw=&gclid=CPbn35u9hsECFVDItAod5woAtA is that what the voltage free contacts are?

 

[bernardgreen]

From the data sheet it appears that the TT04 and the similar TT04 do require a direct Neutral feed

For other wiring, the terminals are marked as follows:
L Live supply
N Neutral supply
N OUT Neutral output to immersion heater
(NTT03 only).
SL Switch live output to immersion heater
(NTT03 only).
S in Live Input for volt free output
(NTT04 only) If volt free is not required,
fit a link between L and S in.
S out Switch live output to heater or other
appliance (NTT04 only).
Note: this device needs to be left to charge for
a minimum of 15 minutes once powered up,
before it will operate.

 

[JohnW2]

So are there any timers that will fit on a standard 1 gang backbox but have no minimum operating current that you know of? edit: just found this http://www.tlc-direct.co.uk/Product...=adwords&kw=&gclid=CPbn35u9hsECFVDItAod5woAtA is that what the voltage free contacts are?

Yes, that ought to do. In fact, any timer which has a neutral feed is likely to be OK, since it does not rely on current through the load (as mentioned by bernard) to power the electronics. 'Voltage free contacts' means that the output is just a pair of (probably relay) contacts which are connected to nothing and can be used to switch anything (within their ratings!) - just like an ordinary switch (other timers may have one side of their 'switch' contacts connected internally to the mains live, hence not 'voltage free').

Kind Regards, John