"The Medway Handyman" wrote in message
. uk...
Andrew Gabriel wrote:
In article ,
"The Medway Handyman" writes:
Someone recently described a 500w PIR flood light as "fixing a half
bar electric fire outside".

Which has got me thinking. Especially given the unreliability of
500w halogen lamps/lights.

So, given the choice between a 500w PIR halogen & an 11w CFL dawn
dusk light - which will be cheaper to run?

Obviously an 11w CFL dawn/dusk will be on for a much longer period,
but is low energy, won't be triggered randomly & will have a longer
service life PIR lights being a PITA IMO (sorry Rob)!

On the other hand a 500w halogen PIR in theory will be on for much
shorter periods, but will consume much more power.

Again in theory an 11w CFL could be on for 45 times as long for the
same energy.

So which one is the best deal for the customer?

Depends what the customer wants. However, if an 11W CFL is good
enough for the customer, a 500W halogen was never required in
the first place. An 11w CFL is nearer to a 40W light bulb.

I find people have two thoughts on this. One is security lead, "a light
switching on will deter burgulars", the other is convenience lead " if
we/visitors arrive after dark there will be a light on".

I'm starting to think dawn/dusk meets both criteria. Just wondering about
the energy costs.

If people believe a cheap PIR will deter burgulars then invite them to look
at having proper window and door locks fitted and tell them to use them.
Dave, you could make money fitting good locks not crappy PIRs (or both)

Adam