PIR or photocell controlled lighting?

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PaulUszak

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Thisi follows on from http://www.diynot.com/diy/threads/security-outside-lights-that-come-on-with-movement.470443/ I've struggled with this concept for a while as there seems to be conflicting advice. I would be interested in the opinions of some other people than just the police.

The following is an extract from the Metropolitan Police website http://content.met.police.uk/Article/Lighting/1400011144993/1400011144993

"In most cases, the preferred and cost-effective security lighting option is low wattage bulbs activated by photo-electric cell which will automatically switch on from dusk till dawn. The alternative of passive infra-red lights can be accidentally triggered by pets or wild animals and must be thoughtfully positioned to avoid annoying your neighbours"

You will find that this advice is repeated by most of UK police forces. They do not suggest installing PIR operated lighting. They suggest automatic dusk till dawn lighting. Why? All DIY shops sell PIR lights, but hardly anyone sells a photocell. All those funny coloured wires can be confusing, so clearly a photocell requires a higher level of electrical comptency to install, but is that the only explanation? Is it just marketing?

The only reason I can think of is that to activate a PIR, you have to be in front of the PIR. That means you're already in the garden with your swag bag and crow bar when the light activates. If the light is on throughout the night, you'll have to access the garden whist lit up. Security principles suggest a multilayered approach, so I would have thought that it was prudent to stop Raffles at the perimeter, rather than encourage him into your back yard...
 
Paul, I think they are more concerned about the light intensity of most PIR floodlights and it causing neighbourly disputes. Dusk till dawn lights aren't usually as in your face. I have both with my GJD setup in that I can programme my lights to come on/stay on when I like or just via PIR operation. I also have no neighbours to worry about the whining too.
 
Problem is ... Most people want to pay for a £9.99 cheap made in China , picks up a moth farting security light with the sensor in the wrong place for the light and the light in the wrong place for the sensor . Ask them to pay £150-200 for a GJD system and they have a heart attack...
 
sparkymarka said:
Problem is ... Most people want to pay for a £9.99 cheap made in China , picks up a moth farting security light with the sensor in the wrong place for the light and the light in the wrong place for the sensor . Ask them to pay £150-200 for a GJD system and they have a heart attack...
Click to expand...
Yes, and I think that is the problem recognised by the authorities who have little control over anyone putting up a powerful, misplaced flood light initially and so recommend a less amateur installation in the hope homeowners listen.
 
Hmm, a couple of points.

The most important point not addressed above is where the burglars are when they are visible. I'm not sure of the answer, but with PIRs the bad guys have to be on your premises, in your yard or just outside your cat kennel. They won't know that there is lighting before entering. Can this encourage them? Is it too late by then? Personally, I would like to advertise that they'll be lit up during their incursion rather than at the last moment. All things being equal, what would a commercial premises like a bank do? Permanent or intermittent lighting?

Secondly, I'm not sure of the distinction between light fittings for dusk to dawn operation and PIR in terms of brightness. If I have some

http://www.screwfix.com/p/luceco-led-slim-floodlight-30w-black/8464k
http://www.rselectricalsupplies.co.uk/floodlight-250w-son-black-cf250s_31

on a photocell, are they significantly less bright than a 400W B&Q security flood light like

http://www.diy.com/departments/elro-gloss-black-400w-mains-powered-pir-security-light/1466025_BQ.prd

on a PIR? The GJD kit looks okay, but what does it control? 400W floodlights?
 
PaulUszak said:
The only reason I can think of is that to activate a PIR, you have to be in front of the PIR. That means you're already in the garden with your swag bag and crow bar when the light activates.
Click to expand...

The PIR sensor can be remote from the lamp it is controlling. If the intruder is walking into the front garden and a light elsewhere in the house or garden comes on then he ( or she ) may feel there there is someone at home and be less inclined to break in..
 
To answer your first question, Paul. I have more PIRs than lights and therefore if I haven't set my lights to a set time they still come on, (or however many I choose), long before they reach my property if they attempt to come up the external driveway or from across fields, because of the strategically placed PIRs. Not only that but the PIRs are also connected to cameras that move according to which PIR is triggered.

From memory the GJD can switch up to 3000watts of lighting.
 
I'm sure if you're prepared to connect a separate photocell to any light then the brightest is solely down to the power of the light. Why you'd want a 400watt light on constantly for 14 or 15 hours a day in winter though is debatable.
 
Twenty Four said:
To answer your first question, Paul. I have more PIRs than lights and therefore if I haven't set my lights to a set time they still come on, (or however many I choose), long before they reach my property if they attempt to come up the external driveway or from across fields, because of the strategically placed PIRs. Not only that but the PIRs are also connected to cameras that move according to which PIR is triggered.

From memory the GJD can switch up to 3000watts of lighting.
Click to expand...
Can I pick your brains please Twenty Four. I've been looking at the GJD system as my next project for my house, I cant seem to work out from the instructions if you can do the following: have the lights come on at dusk till at set time e.g. 10pm and then switch off but go into an automatic mode where they only light on the PIR's, is this possible without manually switching modes each day? cheers.
 
Once the timed period has finished the control panel automatically reverts back to how it was before the timed period. If you've previously manually taken off the green light (auto PIR) and not put it back on then the PIRs won't work at night but you should never need to do that unless you want to creep around your property in the dark. If you manually take off the red light, which is for the audible sound (we do sometimes because of the dog being trained to go mental on a zone 1 trigger only, and the wife might be on a work call or someone might be in the zone working, I.e. window cleaner) then it'll come back to that setting.
 
Twenty Four said:
Why you'd want a 400watt light on constantly for 14 or 15 hours a day in winter though is debatable.
Click to expand...

Absolutely at the heart of my question. It's just that's what (all) the police seem to recommend if you read up on crime prevention strategy. A large floodlight seems expensive to run overnight, but can I play devil's advocate? Could they factor in the holistic cost of a break in? I read somewhere that the mean insurance claim for a burglary is £2000, to which you have to add emotional trauma. I know someone who has an expectant wife and discovered four masked yobs trying to break into his house. How does that equate to electrical running costs?
 
LED equivalents would be cheaper to run/ 1 unit = 1000 watts an hour

so in around 3 hours a 400 watt would use just over 1 unit of electric at 15p a unit ish so 50p ish if on for 9 hours per day, £180 a year. roughly.

I have someone for a quote later today, I doubt they would go for the GJD solution and have never offered it due to cost but sounds a lot smarter. Had a few whinge on the price of an LED pir light fitted.
 
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