P.I.R./Microwave sensors

[karter]

At present I am working in a pub and along with other jobs I have been asked to look at saving energy on the lighting . My electrician intends to fit cfls inplace of halogen downlights and energy saving lamps to all other normally switched areas.The owner has requested that in areas not in constant use,ie a disabled toilet , a corridor leading to two toilets a lobby leading to toilets and the toilets themselves that sensor switching be used.My electrician has suggested using pir/microwave sensors in these areas but leaving the lamps as halogen as CFLs do not like lots of on/off switching.The owner however is dead set on low energy lamps.My questions are , are there CFLs that will cope with the repeated switching and in the toilets themselves if the sensor was in the open wash area would it detect a person in a closed door cubical.I understand that this is a DIY forum but would realy appreciate your advice.Many thanks in anticipation.

 

[Space cat]

LEDs are very efficient and do not mind being switched on and off.

 

[bernardgreen]

if the sensor was in the open wash area would it detect a person in a closed door cubical.

Maybe, but if they were sitting still then they would be invisible to the sensor which reacts to movement of a heat source.

a corridor leading to two toilets a lobby leading to toilets

To leave these areas in darkness could lead to safety hazards. There could be a trip hazard if the reaction time of the sensor and light is too slow. There may be legal requirments for public areas to be lit when open to the public.

Opening a door and finding the corridor in darkness could arouse fear of a mugger waiting to attack. ( not likely but a drunk doesn't think rationally ) so door sensors to turn the light on before the person enters the corridor would be the better option than a PIR sensing a person in the corridor.

Low energy lighting left on when the pub is open would be the best option. Pay back time for the cost of sensors needs to be worked out. Replacement of lamps that have failed prematurely due to frequent switching is a long term on-going cost.

 

[Steve]

LEDs are very efficient and do not mind being switched on and off.

Agreed, this would be the ideal solution. Dont buy cheap LEDs though

 

[Space cat]

There could be a trip hazard if the reaction time of the sensor and light is too slow.

I can hardly believe that I forgot this one. We have sensor operated lights in quite a few places around here, including the toilets, and they can be slow to react. Being fluorescent doesn't help either. Time and again I walk into a store room and have to count three before I can see where I'm going. The alternative is to walk in anyway and hope to hell that the lights come on before I hit something.

If you are going to go down this route, I strongly recommend that you have some minimum level of lighting that's always on.

 

[Adam_151]

Last job I was on where it was speced, called for standard switch and OS, I wired it so the switch was upstream of the OS, so that when you walked into the room and hit the switch the OS would initially bring the light on before movement was detected so that it came on straight away, the OS was just there to ensure that should someone forget to switch it off, that it wouldn't be on for ages (this was in the lobby, WC, store and plant rooms of a building that would only see occasional use)

 

[bongos]

We have sensor operated lights in quite a few places around here, including the toilets, and they can be slow to react.

We also have sensor operated lights, ours are in all the toilets at work. Some of the older gents find themselves left in the dark 'mid-drop'

It'll probably be wise to make sure that this doesn't happen in the pub as there might be some upset customers.

OOI, if you were to replace all the downlights with LEDs then I assume it could take a long time for PIR sensors to pay for themselves anyway - due to the already low cost of running LEDs.