I'm about to buy some twin 5' fittings for use in the garage, but I see Screwfix offer a high power factor and a low power factor variety - which apparently use different tubes.
Which one should I buy, and why?
Any other considerations?
TIA
You may use either. Industrial and large commercial users must use HPF. The difference is that the HPF ones have circuitry to reduce the inductive load to ensure that the current and voltage waveforms are in phase. This enables electricity to be supplied to it more cheaply, as a low power factor reduces the overall current and efficiency. There will also cause less wear on any light switches with an HPF type.
I'd use HPF, unless it was extortionately expensive.
Christian.
If you are only using a few (not dozens) there's no real need for HPF versions. Also the tubes (T8, 58W) are the same anyway. JB
They don't use different tubes, unless they are also different sized fittings. The tubes can't tell the difference.
Doesn't make much difference for one or two fittings. The low power factor ones draw more current, but don't use more energy or cost any more to run. When working out current draw for load/cable/switch sizing, double the current you would expect from the tube's power rating. For high power factor fittings, this is not as much of an issue. Commercial/industrial consumers are only allowed to fit high power factor fittings now by EU regulation, but this doesn't extend to residential use. (Actually I think this is an EU directive which I've seen no sign of in UK law yet.)
[oh -- started writing this hours ago before getting distracted and I now see most of this has already been said...]
Thanks Andrew, Christian and JB.
The reason I thought they used different tubes is because the Screwfix catalog (72b) lists the fitting 11208, which is a
1500mm twin HPF fitting, but also says tubes *not* available separately, even though they stock 1500mm 58W T8 tubes!
I know it's not what you asked, but the last time I looked at fluorescent prices Screwfix were waaaay more expensive than B&Q's budget fittings.
-- John Stumbles
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Really? I thought that £70 for a pack of four twin 5' fittings was pretty good.
Can you remember roughly what the B&Q ones cost? (I had a look on the B&Q site, but it's pretty useless, as usual)
Thanks.
Nice to see you on this NG also Andrew. More happenning 'at the sharp end' on this NG than sci.engr.lighting. all the best, JB
These are also plain, no diffuser etc. They list a 5' single HPF at £33 for four units. They don't do them individually.
I suspect their prices have come down since your comparison.
fluorescent
sounds good to me too
dunno about doubles, but last time I was after one singles were about a tenner (no diffuser or anything fancy like that, natch)
It was about a year ago I compared prices with Screwfix
-- John Stumbles
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-+ I've got a book about motivation but I've never got round to reading it
Local electrical wholesaler has 5' twin fittings at £14 + vat, which is pretty close to the ScrewFix price. I wouldn't expect B&Q to be a lot cheaper.
Hi.
HPF. LPF fittings are for use in quantity with a separate power factor correction cap fitted to the whole bank. This is a little cheaper for commerical users. LPF fittings used without exernal power factor correction use more current. What your lectrickery meter makes of it depends on what kind of meter you have.
There are many tube colour variations: avoid 'cool white' or 4500K, they are the real nasty ones. Cool whites are what gave fluorescent lighting a bad name. Most other tubes are OK.
Regards, NT
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