Hi,
Looking to fit a photocell(s) to some outside lights, which contain low energy (CFL) lamps.
Many of the photocells say they are not suitable for Low Energy Bulbs? Why is this?
Will it damage the bulbs or photocell, or both? Is it due to a higher start up current?
Only looking to switch 22watts on one photocell and 52watts on a separate circuit.
Is it worth the risk?
Hoping someone can explain this one!
Many thanks
Matthew
On 14 May 2007 05:09:13 -0700 someone who may be Matthew wrote this:-
Alternatively one can get dusk to dawn luminaires designed for bulbs like the 2D.
Largely because some of them avoid having a connection to the neutral conductor to save a few pence.
Unfortunately the lights are already installed and wired in.
Should they work with CFL's, but its not recommended etc?
Thanks
Matthew
It's due to the photocell expecting to power itself by passing a low current through the filament during daylight hours. This doesn't work with compact fluorescents. It would probably stop the photocell working properly, and might damage the CFL longterm.
Look for a professional quality one of the type used in streelamps which have a neutral connection and relay to switch the light, and will be rated for something like 1000W. Here are some which you can add to an existing luminaire...
Because they are designed to replace a switch, and therefore have no discrete neutral to complete a power circuit to operate them. They obtain the neutral via the much lower resistance of a filament bulb in the 'off' state. CFLs have a much higher 'off' resistance so don't 'bleed' through enough current. That's the usual reason. Other reasons may be the electronic switching can't handle the inductive load of a CFL.
Ah, I see.
That explains why the light in the study, which has a security switch on it (photocell and random timer) flickers slightly during the day with a CFL in it. They were in when we moved in, so never even thought about them not working with CFL's.
Looks like I'll have to replace them (the switch)- now the house is about 95% CFL's.
All makes sense now!
Cheers,
Matt
On 14 May 2007 05:31:00 -0700 someone who may be Matthew wrote this:-
Depends on the photocell, for reasons already explained. Get the ones that will work properly, often the more expensive ones.
no and no
The other option is to put one filament lamp and the rest CFL on each photocell. The filament lamp can be 15w if preferred - or even lower.
NT
Maybe the photocells could be connected to a relay and that could operate the lamps?
M
A relay works by being inductive itself... :-)
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