Flourescent tube

[smix]

'Somebody' is doing my head in by insisting on leaving the flourescent light in the kitchen switched on all the time. If I switch it off, they screech at me that when you switch a flourescent tube on it uses far more electricity than if you leave it on most of the time. They leave it switched on for hours at a time. I asked who told them this and they replied 'an electician'. The light is a 70w flourescent tube. I've tried to point out that even if it used 100x more electricty in the two seconds it takes to 'warm up', that it is only the same as having it on for 3 minutes and 20 seconds. (I'm sure that if the light ran at 7kw it would overload the lighting circuit anyway).
Anyway, they won't believe me! I just thought that if somebody else (preferably a qualified electrician) would agree with me, I might get them to see sense. Otherwise I'm sure I'll never hear the end of it!

 

[breezer]

i am sorry to say this but they are right.

When you turn on a flourescent tube you do indeed get a high voltage to "strike the tube" this voltage is produced by opening and closing the choke (coil inside the fitting)

after the tube has been "struck" the choke then limits the current that the light uses. the initial amount of current drawn is not really that great, but as i said after the tube has been "struck" the current it uses is very very little.

Other useles facts:

it is called a flourescent tube because after striking the gas inside (can't remember what it is) actullly glows and gives off very little light,(U.V) the glass tube is coated with a powder that gets "exited" or flouresses by ultra violet light

 

[masona]

We have 4 flourescent tubes in our utility room (can't remember the wattage) and my wife go in there switch the light on/off approx 3 to 4 times and total light time been on 15 minutes,so would this be cheaper to leave the lights on for the whole evening?

 

[breezer]

its debatable, but in theory yes it would, the real problem arises when they are left on for "too long" that is to say leaving them on because its cheaper than turning them off, if you see what i mean

 

[masona]

Heeeey Scobbbbby where are yer ?

Me, the old lighthouse keeper switch specialist and you are now redundant

Forget them downlighters in your lounge,use flourescent tubes instead and leave them on all the times,no more worn out wall light switch

 

[ban-all-sheds]

As I understand it it's not the power consumption that's at issue, it's the overall cost of the light you get, and the trade-off is based on the shortening of the life of the tube (and to a lesser extent the starter gear) compared to the electricity consumption of leaving it on.

I don't know where the balance point is, and I suspect that the tube manufacturers won't tell you as they want you to keep buying their products.

I did read once that if you were designing a new installation it was cheaper to have fluourescent tubes on all the time, but that factored in not only the tube life but also the materials and manpower costs of installing cables and switches vs none of that. And it was so long ago that changes in the relative prices of electricity, cable, switches, tubes and labour would mean that those particular calculations are now invalid.

Which is a very long-winded way of saying I dunno.

You could set up a test by having 2 fittings, one switched and one on all the time, but you'd have to put the unswitched one in the loft, for example, or you could never be sure that the switched one in your kitchen, or wherever it is, was turned on as often as it would be if there was no lighting already present.

But my advice is that the difference in tube cost vs energy cost is so small that it isn't worth picking a fight with SWMBO - save that for something that matters, and turn the lights on and off...

 

[Scoby_Beasley]

Heeeey Scobbbbby where are yer ?

Me, the old lighthouse keeper switch specialist and you are now redundant

Forget them downlighters in your lounge,use flourescent tubes instead and leave them on all the times,no more worn out wall light switch

Probably an excellent idea, I've just got in to an empty house, everyone else left at 9 and all the b*** lights are on

 

[paulfromswindon]

Guys, my ha'penny worth:

It is true that the flurry takes a gulp of juice when you turn it on, but in a house with a couple of tubes, it really is irrelevant. It's more of an issue in a shop or office with hundreds of fittings. You really aren't going to save enough to make it worthwhile. Modern Electronic-start fittings are much mor efficient on starting anyway.

Here's a useless fact: When they wired the World Trade Center in New York, energy was so cheap, they never bothered putting in light switches - all the lights were on all of the time.

Have a goog one

Paul