Hello -
In response to local burglaries, some relatives have been advised by the police to install a dusk-to-dawn low-level floodlight in their small (15 metres across) farmyard., which already has motion-activated halogen lamps.
The police recommend a sodium lamp, but are the CFL-based floodlights also suitable? Sodium lamps with dusk-til-dawn sensors seem to be quite thin on the ground, should I use a separate sensor? Can anyone comment on whether these might be suitable?
Well the reviews on the latter say it isn't much good.
Decide how much lighting you want.
- SON re industrial sodium yellow light
- Fluorescent re conventional warm-cool white light
Decide how you want to control them.
- Single industrial photocell on wall switching the lot
- Individual photocell integrated into each light unit
Lights with integrated photocell provide better reliability at higher cost, industrial photocell (box on a wall) are however quite reliable.
Ebay had some Coughtrie cbc IP65 photocell fluorescent lights for =A39-14, diecast aluminium opal diffuser, normally =A345 normally as proper industrial lighting gear. Nothing like them on there now unfortunately as the price was excellent. Do not use the ASD bulkhead photocell, they used to fail quite often.
Going for "real" IPx4 or IPx5 is a good idea re fit-n-forget. Go to any electrical wholesalers and see what they have.
On Sun, 24 May 2009 18:26:05 +0100 someone who may be "Johnny OneSpanner" wrote this:-
Depending on the particular sodium lamp, sodium lamps are likely to have a lower life-cycle cost due to the lower running costs for a given lighting level. OTOH it will be more difficult to achieve an even level of illumination with sodium lamps, as fewer will be needed for a given level of illumination. However, fewer lamps may mean less wiring depending on the particular circumstances.
I would go for sodium lamps, there is a selection at
They have advantages and disadvantages, the main disadvantage being that if it fails there will be no light at all, or light all day. If you go for one drive a relay/contactor from it and use that to switch the lamps.
Yes, but they're less efficient, both the raw lamp itself, and because it's not possible to design luminare optics for such a large light source as efficiently.
Yes, but you should go and try an electrical wholesaler, who will have a better selection than ScrewFix.
The various types of sodium light all have way better energy efficiency, and thus lower run costs, than CFL
NT
SON (high pressure sodium) are a peachy, very warm white, but don't have good colour rendering.
SOX (low pressure sodium) are the really yellow ones with no colour rendering, but I doubt you'll find any (new) SOX fittings, as the lamps are being phased out. (Somewhat ironic given they're still the most efficient widespread light source available.) Councils should have programmes to swap these out, and you might be able to pickup some cheap, but make sure you also get a lifetime stock of lamps, as they will become unavailable (and they're expensive - I think there's only one manufacturing facility for them still left).
Can't add much to what others have said (but 70W SON would be my first choice).
However, I recently brought this stand-alone dusk-dawn sensor from Toolstation and it's OK (as in good value for money - but not industrial quality):
De-rating for 70W self-igniting discharge lamps (e.g. Osram 70W SONI-E), it should comfortably switch up to 8 Luminaires.
If they've got motion activated halogens allready where's the advantage in having other
lights that are ON all the time it's dark,is there something wrong with the MA lamps or
sensors? are they positioned too low down so they can be interfered with? or is it that
the ON time is too short. Would they be better off investing in a camera,siren or something else in addition to the existing lights, or am I missing something here?
Don
Thanks for all the comments. For wiring reasons, there will probably be only one light, so a 70W Sodium lamp looks like a good solution.
I'm a little surprised that the police recommend dusk-til-dawn low level lighting, but I supose the reasoning goes something like this:
- It provides a visible deterrent for any burglars scouting the area, hopefully they will be discouraged before they ever get within range of the halogen lights' PIRs.
- It provides reassurance to anyone looking out of a window (or through the camera, which is also installed), that no-one is sneaking around, having somehow dodged the PIRs. Because of the layout of the property, it's difficult to provide 100% reliable PIR coverage without getting lots of nuisance triggers from cats, foxes, sheep, etc.
NT
You need to mount it high up too.
Ideally, you should get the photometric data from the light's datasheet, and work out the correct mounting hight to cover the area. In practice, you might find this data doesn't exist unless it's a good make, and that the mounting height it gives you is higher than you can manage.
If you have neighbours, check that either the light doesn't spill onto their property, or that they don't mind. If there's a road nearby, check the light doesn't cause dazzle to road users. Always adjust the light so the beam cutoff is below horizontal to minimise light polution.
Yes! I do a bit of amateur astronomy and security lights are one of the banes of my life. Most of them spill light upwards which is both a waste for the owner and a nuisance to me.
Another Dave.
Another option might be a 70 watt HQI metal halide[*] lamp. Much better colour rendering than SON and pretty good lumens/watt efficiency, although not quite as good as sodium. Googling "hqi floodlight photocell" finds a few suitable luminaires.
[*] Don't confuse "metal halide" with "tungsten halogen" - they're totally different things.Donwill"
SOX is near single line output, can use a dichroic filter to notch it out.
Light tresspass is a real problem, now entering legislation in Scotland, mounting a sharp cutoff flood high, pointing down should keep it to a minimum, Ofetn see them mounted far too low with resultant spill everywhere, in the contryside its not just people who need darkness at night. Remember light not on target is money going to waste.
Adan
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