Talk:PIR

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will delete this later...


Needs an intro to explain what a PIR light is... and why you might want one.

Not sure I would limit the application just to "security" though, it can be as much about convenience, or safety.

(Much of this article is really about outside lighting in general, rather than PIR specifically)

> ==Power== Fittings with excessively bright lights aren't unusual, > especially with halogen lamps. 118mm linear halogens can be had > in a range of powers, but 80w is more than is ideal for a percentage > of cases.

> Power required depends on circumstances and desired light level. The > following is just a rough starting point: * Terraced house close to > road 40w * Small terraced back garden 60w * Semi set back from road > 100w * Large area 100w - 1kw if mounted high enough.

I agree that people often go OTT on power - the height of the lamp is one of the real keys. However you also need to consider what you need the light for. Walking safely from one place to another in complete darkness needs far less light than illuminating a space so that you can carry out a task in the light.

So walking safely to the dustbin at night requires far less light, than that required for sorting rubbish into the right dustbin when you get there!

> ==Bulb type== Filament lamps occasionally arc over when they > blow, killing triac type PIR units. They're low [[energy > efficiency]], but aren't on much time in total, so run cost is > minimal. > > Halogen/xenon capsules inside GLS bulbs do the triac death trick much > more frequently.

You seem to be assuming people know what a triac is before you get to the section...

> CFLs are unsuitable for PIRs unless specifically designed for > them. Ordinary CFLs have very low output in cold weather, with > frequent switching they have short lives, and since they're always in > warming up mode the energy efficiency is not good in winter time. > CFLs and triac fittings aren't compatible (though you can use CFLs > plus one small filament lamp).

That seems to be limited to the kind of PIR that acts as a light switch replacement. Any with a L & N feed would be fine switching a CFL,

> LEDs are a good choice where they provide enough light, > though they have their pitfalls, mainly the poor colour of some white > LEDs, and for some situations bulb theft risk. Some fittings come > with non-replaceable LEDs; lifetime should be fine if it doesn't stay > on too long. * 3 minutes 10x a day = 180 hours a year ** 25,000 hour > life would give 138 years life * 12 hours a night = 4380hrs/year ** > 25,000 hour life would give 5.7 years life > > Linear halogen are very prone to excess brightness and severe > glare. Tenants can be confused about which of the various similar > replacement bulbs to get and don't know how to fit them, making them > not always maintained in rental properties. > > Some fittings only take one bulb type. Fittings designed for > filament lamps can take a wide range, typically including > filament, halogen capsule, CFL, LED, and even > oddities like carbon & neon lamps. > > ==Relay v triac== Some PIRs switch the light with a triac, some with > a relay. Relays make a quiet click, triacs are silent. Triacs are > vulnerable to being killed by the various types of filament lamp, > including halogen.

Might be worth mentioning that the max power handling is usually a good indication of the kind of switching element if all you have to go on is what it says on the box. e.g. max load 150W - probably tirac, max load 1kW relay...

> ==Reflectors types== Bright metal reflectors send light in a > specific direction, good for when you want a limited angle of > illumination. > > White reflectors send light every which way, and give a softer > appearance. Good for short range illumination. > > Grey reflectors have been spotted! Needless to say these are a daft > choice. Painting them white improves light output per power > used. > > Many fittings send light skyward. That's energy you pay for wasted. > > Many fittings have large areas of black interior, wasting light. This > is true of a lot of Victorian coach style fittings. Painting > white or lining with aluminium can improve light output per power > in. > > Coach style lights put a lot of light out behind them. Replacing or > lining 1-3 rear glass panels with aluminium can reduce the bulb > power needed. Fizzy drink cans provide free aluminium that's easy to > work. Folding the ali over double conceals the painted side.

Much depends on the colour of the wall they are mounted on... - show quoted text - You could link to the diagrams on the two way switching article that show this.

> ==Extra modes== There's some tendency for PIRs to need adjusting > years later, and they often have a walk test mode. Keep the > instructions for when you need to do this. > > Many also have a mode or 2 entered by operating the lightswitch > repeatedly. Needless to say these modes are more often an annoyance > than useful. Switching power off to the fitting for a couple of > minutes resets them. > > ==Dimming fittings== These can literally cost thousands of pounds in > wasted electricity. Running a fitting that keeps a filament or > halogen lamp on all night in dimmed mode is a truly poor > idea. There are much better ways to provide all night low level > lighting if its what you want.

Might it not be simpler to say that running a filament lamp in dimmed mode will cost nearly as much as it would cost to run full on for the same duration. Its not up to a wiki article to decide if this is good or bad.

(some dimming fittings contain two lamps, and in effect behave as a switch bank - one lit via a dusk to dawn sensor, the other brought in by PIR)

> ==Fitting syles== A few warrant specific functionality comments. > > Coach lamp type fittings can benefit from replacing or lining some > glass panels with ali, ditto the lid on black units. Panes can be > filled to deliberately control where light goes, eg to avoid annoying > a neighbour or bedroom.

This is repeated from higher up.

> There's no need to use an all-in-one PIR fitting. Standalone PIR > detectors can be used with any type of fitting that suits the > situation, giving a very wide range of choices.

I would make that a bit more prominent in the article. In fact in many cases having the PIR remote from the lamp(s) it controls is preferable.