Photocell or PIR?

[easygoingchap]

Hello all,

I'm a new member, so thanks for reading and any replies are appreciated. I have been asked to replace a couple of 150W halogen fittings on the outside of an office building. The fittings at the moment are being controlled by a PIR.

I have recommended replacing halogens with 2 compact fluorescent fittings controlled via a photocell with an override switch inside.

However, the client is insisting on keeping the PIR.

My question is this: will the compact fluorescent fittings operate OK on a PIR? I was always under the impression that they didn't like being switched on and off like that. What would you recommend?

Thanks for any replies, great site btw!

 

[DurhamSparky]

will work fine!!

 

[bugsy]

They wont work on a Photocell or pir unless you wire them through a contactor if the experiances I have had in the past are anything to go by

 

[Marvo]

They should work fine on either if they are the relay type. The solid state switched type can give problems with CFL lamps.
I don't see the point of PIR switching, won't save much energy and will shorten the life of the CFL's. Also PIR's are prone to nuisance switching if they're not particularly good ones. I would stick with a photocell unless the customer is AdamAnt.

 

[telectrix]

i.d fit new halogens. hate cfl lamps. about as much use as candles on a motorbike

 

[easygoingchap]

Thanks for all replies to date, I know it's not a big issue but just wanted to check. I have been explaining the benefits of a photocell, and the constant switching with a PIR, but to no avail. At least I can tell him a PIR should work OK, if he insists.
Thanks again

 

[WDMDL]

Depends on the amount of time the lights would be on really.
For a low traffic area, I'd go with the halogen on PIR for instant bright light.

For a high traffic area I'd go with compact fluorescent fittings (eg PL-type, with ballasts - not domestic CFL type) on a photocell
or even metal halides. A 70W metal halide would give far more light than a couple of 150W halogens, but only any good on a photocell.
Your customer would see the benefit in reduced maintenance (relamping) costs too.

Problem with most new-tech fluorescent lamps (T8, but especially T5 and smaller diameters) is they don't reach full light output for a few minutes, more so in cold weather - my outside light lit up a dim PINK for the first few minutes every day in those sub zero temps we had the other week!

As Telectrix said, candle on a motorbike lol

Simon.

 

[Marvo]

It's swings and roundabouts choosing what lamp is best. Metal halides and halogens run very hot, they're energy hungry and the heat takes its toll on the fittings. CFL's aren't as bright in general and don't take kindly to regular on/off cycling. CFL's and PL's can be a bit iffy in very cold whether as well. LED's are expensive to buy but very efficient and won't worry about being switched for short periods by a PIR. I saw some flood lights the other day which had a few hundred LED's rated at 720lumen output

 

[dave1234]

A lot of the above is quite correct, but the most important thing is that the PIR or Photocell that you use must use a relay for the switching element. Most PIR's use an electronic device called a triac for the switching element as these cost penny's. Most Photocell's use a bimetalic switch controlled by a small heater element and these rely on a minimum load so are also unsuitable for low energy lamps. The contact material of the relay is also important if you want it your photocell to last with these lamps, the contact material must be Silver-tin-Oxide.

 

[Amp David]

I've had a cheapo bulkhead fitting with a photocell running a CFL for the last 7 years and never had 1 problem with it.

 

[easygoingchap]

Again, thanks for all the replies

I'm still waiting for the client to make a firm decision on which way to go, but it looks like I'll be fitting new halogens with a new PIR. Honestly, you've never seen so many email flying around at work about this lol.

Anyway, this would eliminate the slow warm up and candles on a motorbike problem! I will check when ordering PIR that it's the relay type.

I wouldn't mind but the rest of the outside of the building is lit up like a Christmas tree all night

Good advice, thanks everyone for your comments