2 x 24W T5's - what do they use in electric ?

[tubamanandy]

Any ideas roughtly what 2 x 24W T5's use in electricity per hour ?

I know its not as simple as Watts=Volts X Amps because I believe they only use a large amount of electricity when first starting up then level out at a much lower rate.

Can someone enlighten me ?

 

[foxfish]

1000w = approx. 0.12p per hour so approx. 0.6p per hour... 0.6 x 8 = 4.8.... 4.8 x 7 = 33p a week ... or about £17 a year.

 

[ian_m]

They use 48Watts. Watts is energy per second, so the amount of electricity per second is 48 Joules/second. Not really useful.

Startup current surge does occur however it is short and not really relevant when lights are on for hours at a time.

You really want £ per hour. I pay £0.15 per 1000Whr.

So cost per hour is 48/1000 x 0.15 = 0.72pence per hour, bargain.

 

[tubamanandy]

So they do use the full 48W and not just for starting, looks like its a simple watts=volts x amps calculation then assuming you know your electricity costs

 

[ian_m]

Actually all that is not quite true. The efficiency of the ballast driving the lights has not been taken into account. A cheap inductor style ballast will have 20-30% losses (on top of 48W) and an electronic ballast usually less than 10%. So actual power consumed may be 48W+10% (53W) to 48W+30% (63W).

And that is not even taking into account the power factor. Power factor - Wikipedia, the free encyclopedia

 

[dw1305]

Hi all,
I think "Ian_m"'s figures are about right, you need to add about 25% over the rated value for electronically ballasted linear T5's. As soon as you start twisting the tubes to (get CFL's) the efficiency will go down, in proportion to how folded the lamps are.

cheers Darrel

 

[ian_m]

Or plug in one of these to measure the power (and power factor) directly.

15A Plug In Energy Saving Monitor : Power and Energy Monitors : Maplin Electronics

or

13A Plug In Energy Saving Monitor : Power and Energy Monitors : Maplin Electronics


Not done it for the fish tank for ages. I know 50Watts light, 200Watt heater, 15W canister filter, but would be interesting to log over a week and see how much it has cost.

Anyway, I read a blog where a "big boy" marine person, 700 gallon tank was consuming 2800W 24/7. At my leccy rates that's 2800/1000 * £0.15 * 24 -> £10 a day....£3600 a year just in electric.....

 

[foxfish]

Several of the Koi ponds I maintain use 2kw - 4kw of pumps & with additional heating in the winter can see large electricity consumption but, the same owners might employ £1000 worth of gardeners a week, drive a Porsche 4 x 4 around town & own a 7 bed house ... so I guess it is all relevant to income!