[Moorf]

A friend has finally managed to find dimmable energy-saving bulbs... but... they are $22 EACH!

Has anyone bought them cheaper in NZ? Not sure spending almost $50 is THAT cost-effective for lights we rarely use... :confused: Or, do dimmables (non-energy) cost more to run anyway?

[sweetpea]

They had some at the Palmy Bunnings today, but I didn't catch the price.

[Georgebulldog]

That's so weird you posting this. We have today just changed our light fittings & gone from 5 bulbs to 3 bulbs on 2 of our light fittings. I was only saying 5 minutes ago to the OH "I wonder if you can get dimmer energy saver light bulbs yet" & there you are posting this. :nice1
So we have 9 light bulbs now instaed of 13 but at $22 each wow This will be intersting to see if anyone has found cheaper ones, I'll be looking over the next few weeks so will let you know what I find. I'm hoping just going down by 2 bulbs will help a little

[nippa&pippa]

A friend has finally managed to find dimmable energy-saving bulbs... but... they are $22 EACH!


:D

I don't know if any difference on bills yet as our lounge lights are the light we used lots, so hopefully they help to reduce the electricity bills further :roll
Downside about these dimmable lights is if you turn too low, then the light will cut off complete but they do work :yes

[PeteS]

A friend has finally managed to find dimmable energy-saving bulbs... but... they are $22 EACH!

Has anyone bought them cheaper in NZ? Not sure spending almost $50 is THAT cost-effective for lights we rarely use... :confused: Or, do dimmables (non-energy) cost more to run anyway?

I do not beleive that dimmable energy savers will save enough power to be cost effective in comparison to normal energy savers. Or "compact fluorescent" as we call them in the trade. The sums are as follows:-

Conventional 100W lamp. 434mA

Conventional 100W lamp, @50%. 217mA

Energy saver lamp, 18W. 78mA

Energy saver lamp at 50% of 18W, 9W. 39ma

So you are chasing minimal returns for massive expenditure.

But if you really want to spend money to little effect, try replacing the low voltage dichroic lamps with the LED version. $2 to $50 is the price hike! But that's nearly down to $22, so......

AND, then there are the harmonics induced in the electricity network by dimmers. Network cost will need to go up.

But don't worry about saving power, the electricity supply industry in NZ has found a way to limit power consumption. It's called the Cook Strait Cables, aka, the DC link. It's falling over due to slips in the rain we've had. Ironic isn't it, the South of the South that needs rain to keep the hydro lakes up doesn't get any, while the North of the South gets too much and the pylons threaten to fall over!

[Caroline and Dave]

We got our energy saving bulbs here. They worked out cheaper than in shops and if you buy 4 or more postage is free

http://www.omicron.co.nz/webapps/site/67541/80609/shopping/shopping-plus.html?find_groupid=10926

[Leccy-Lee]

Eeeeww CFL lamps Yuk, I'll stick to incandescent lamps if its ok ;)
And have to second Petes professional calculations above.

[Moorf]

Cool - in that case we won't bother with the dimmables... this forum answers just about every question!! So, about this boil.....

[Caroline and Dave]

Cool - in that case we won't bother with the dimmables... this forum answers just about every question!! So, about this boil.....

You asked :)

http://dermnetnz.org/bacterial/boils.html

[Leccy-Lee]

LOL

[bob_the_engineer]

I do not beleive that dimmable energy savers will save enough power to be cost effective in comparison to normal energy savers. Or "compact fluorescent" as we call them in the trade. The sums are as follows:-

Conventional 100W lamp. 434mA

Conventional 100W lamp, @50%. 217mA

Energy saver lamp, 18W. 78mA

Energy saver lamp at 50% of 18W, 9W. 39ma

So you are chasing minimal returns for massive expenditure.

But if you really want to spend money to little effect, try replacing the low voltage dichroic lamps with the LED version. $2 to $50 is the price hike! But that's nearly down to $22, so......

AND, then there are the harmonics induced in the electricity network by dimmers. Network cost will need to go up.

But don't worry about saving power, the electricity supply industry in NZ has found a way to limit power consumption. It's called the Cook Strait Cables, aka, the DC link. It's falling over due to slips in the rain we've had. Ironic isn't it, the South of the South that needs rain to keep the hydro lakes up doesn't get any, while the North of the South gets too much and the pylons threaten to fall over!


I’m not an electrician, and I’m certainly not in the know about the intricacies of dimmers, various lamps and efficiencies.

Just a thought that flashed through my mind (excuse the pun) when I read your sums on power use in conventional lamps.

(and so bob starts his dull jibber jabber)

If you take any metal and heat it, the electron sphere of influence that dictates collision rate in the metal increases.

A dimmer will inherently pulse energy into the metal, so much so that a zero cross over has to be included to prevent you shaking the lamp to pieces.

Now I’m quite sure that the amount of energy you pour into an incandescent bulb isn’t proportional to the light you get out of it, I think its top heavy i.e a small variation in the maximum power produces the variation in light. Add to that the increased current due to the reduced filament temperature, so I would have thought that you would be shoving almost as much energy into an incandescent bulb for a dimmer light level.

So I don’t think its correct when you say “Conventional 100W lamp, @50%. 217mA” particularly if you mean 50% brightness.

Onto the “compact fluorescent” I don’t know much about them, I think they use a gas discharge principle. That is you take a tube full of gas and stick a small heater at each end, then you spike a high voltage across them to get the initial breakdown in the gas. I think that’s what the starter circuit does. Once the breakdown has occurred you can run a stream of electrons through the gas at a much lower potential. Let me re-iterate I’m guessing here. I think the flowing electrons throw the outer shell electrons (in the gas) into a higher energy level, and when they decay they emit a photon that’s below 400nm (UV’ish). That photon is absorbed by a fluorescent coating in the tube, then re-emitted as a photon in the 400-700nm range (visible).

The tubes are strange shapes, quite honestly I’m not sure about how that works.

Anyway if I wanted to dim a fluorescent tube my first approach would be to vary the rate of electron flow in the gas. That is to say I’d start to play with the frequency of the current I pass into the tube. I wouldn’t want to allow a complete breakdown in conduction through the gas, because that would involve an energy hungry re-start. I’m guessing that’s where the “dim too low and it switches off” part comes from.

Sure you get a switching losses, but I’d expect that to be tiny even at tens of thousands of switches per second.
Nothing approaching the losses I mentioned for the sphere of influence effect.

So onto the two points I’d like to make.

My first is, if you read all that you now understand why most people would rather not start a conversation with me LOL, yes I’m dull (another fantastically funny pun from bob).

The other is I think the figures your giving are rather misleading, I’m willing to accept my little theory is wrong, but I’d have to grab a scope, current and voltage probe and measure it first (a meter won’t give an accurate result).

I think the efficiency of a dimmed energy saving lamp is superior to the efficiency of a standard lamp.

Bob