Little confusion here :

Energy is quantified in Joules. Things that are energy and therefore can be measured in Joules are for example :

 - Energy contained in a battery

 - Energy contained in a volume of fuel

 - Energy it takes to heat up some volume by a predetermined temperature difference

 - Energy it takes to lift a mass to a predetermined height



Power is how fast the energy is getting moved, converted and such. Power is measured in Watts, which equal Joules/Sec

 - The 70W Metal Halide lamp converts 70 Joules of Energy into (light + heat + ...) every second it works

The unit allready contains the division by time within, so there is no such thing as "Watts a day", cause that means "Joules a second a day" - It makes no sense in the sense we are trying to use it here

(there are possible cases where Watts/Day can be meaningful. For example, when you say something like "the electricity damands of our town are growing by 100 watts a day" - That is, one day the average load was 100000W and the next day it was 100100W)



When you multiply (and not divide !) Power with Time, then you get Energy :

 - The 70W Metal Halide lamp converts 70 Joules of Energy into (light + heat + ...) every second it works. Over a minute that is 4200 Joules

 - If you were to run it on battery, a battery that contains 42000 joules would last 10 minutes

 - If you connect 2 70W Halides, the battery with 42000 joules would last 5 minutes



Units can be converted. For example, power company measures energy consumption in KWh That is KW multiplied with Hours. 1KWh = 1000 * 3600 = 3.6M Joules

Little confusion here :

Energy is quantified in Joules. Things that are energy and therefore can be measured in Joules are for example :

 - Energy contained in a battery

 - Energy contained in a volume of fuel

 - Energy it takes to heat up some volume by a predetermined temperature difference

 - Energy it takes to lift a mass to a predetermined height



Power is how fast the energy is getting moved, converted and such. Power is measured in Watts, which equal Joules/Sec

 - The 70W Metal Halide lamp converts 70 Joules of Energy into (light + heat + ...) every second it works

The unit allready contains the division by time within, so there is no such thing as "Watts a day", cause that means "Joules a second a day" - It makes no sense in the sense we are trying to use it here

(there are possible cases where Watts/Day can be meaningful. For example, when you say something like "the electricity damands of our town are growing by 100 watts a day" - That is, one day the average load was 100000W and the next day it was 100100W)



When you multiply (and not divide !) Power with Time, then you get Energy :

 - The 70W Metal Halide lamp converts 70 Joules of Energy into (light + heat + ...) every second it works. Over a minute that is 4200 Joules

 - If you were to run it on battery, a battery that contains 42000 joules would last 10 minutes

 - If you connect 2 70W Halides, the battery with 42000 joules would last 5 minutes



Units can be converted. For example, power company measures energy consumption in KWh That is KW multiplied with Hours. 1KWh = 1000 * 3600 = 3.6M Joules

I think you are getting confused. Running a 70W MH light (About 10% efficient, Lets round down to 60W) is using 70W of instantaneous power, Or 70 Watts in an hour.
Because nothing is 100% efficient, 60 Watts will get converted to heat in 1 hour.
60 Watts X 24 Hours in a day = 1440 Watts in 1 day.

Another thing you can convert is Watts to BTU/h, 1440 x 3.4 = 4896 Total BTU.
Some proof of this is connecting a meter/measuerer to the MH lamp, And calculating how much power is being drawn.

Joules are also useful here, But Watts is usually the better term.

@mbulb146 the torchieres were not previously double ended halogen, but rather just E26 medium screw. I installed new pulse rated lampholders, and the ballasts for both fixtures are Advance 100w M90 F-cans remote mounted in a closet adjacent to the living room, I drilled a 1/2" hole at the bottom of the wall for the lamp cords.

The definition of power (Watts) allready contains the division by time inside it :

70 Watts = 70 Joules/Sec

Joules can be converted to various equivalent units, which all sign energy. One of them is Watt Hours (more commonly KW Hours is used, but Watt Hours is a legit unit). Note that this is multiplication : Watts * Hours. You power the 70W lamp for 3 hours, that is 210 Watt Hours. If you divide that by Hours, you come back to Watts... And that is the 70 Watts power


In the sense we use here, there is no meaning to units like Watts in Day. When you multiply power with time you get energy, that can be for example Watt Hours



For the explanation i skipped everything related to efficiency. Realistic performance of MH lamps is on the order of :

0.91 efficient ballast (modern lowloss ballast)

0.1..0.2 efficient lamp (varies greatly with lamp type)

0.9 efficient reflectors in lantern

The definition of power (Watts) allready contains the division by time inside it :

70 Watts = 70 Joules/Sec

Joules can be converted to various equivalent units, which all sign energy. One of them is Watt Hours (more commonly KW Hours is used, but Watt Hours is a legit unit). Note that this is multiplication : Watts * Hours. You power the 70W lamp for 3 hours, that is 210 Watt Hours. If you divide that by Hours, you come back to Watts... And that is the 70 Watts power


In the sense we use here, there is no meaning to units like Watts in Day. When you multiply power with time you get energy, that can be for example Watt Hours



For the explanation i skipped everything related to efficiency. Realistic performance of MH lamps is on the order of :

0.91 efficient ballast (modern lowloss ballast)

0.1..0.2 efficient lamp (varies greatly with lamp type)

0.9 efficient reflectors in lantern

Oops, I should have said Watt Hours per Day. This makes those odd X" KWH per Year!" ratings invalid.

I think the reason my post did not have WH in it is because it was late at night.

Actually WH/Year that is a unit that makes sense. It is a unit of power... But of average power



Watts = Joules / Sec = Energy / Time = Power

Watt Hours = ( Energy / Time ) * Time = Energy

Watt Hours / Year = [ ( Energy / Time ) * Time ] / Time = Energy / Time = Power



lets say the 70 Watt lamp is working 8 Hours / Day - That is 1/3 of the day

70 Watts * 8 Hours / Day * 365 1/4 Days / Year = 204540 Watt Hours / Year



The 70 Watt lamp uses 70 Watts for 1/3 of the day, nothing the rest of the day. On average (over a day or longer period), it can be said to have average power of 70 / 3 ~= 23 1/3 Watts

Now lets see how the 204540 Watt Hours / Year reflect this. That is, we see that "Watt Hours / Year" is a unit of power, and it means that it can be converted to any other unit of power by simple unit conversion. Lets see how it converts to Watts :



1 Year = 365 1/4 Days

1 Day = 24 Hours

1 Year = 365 1/4 * 24 = 8766 Hours



204540 Watt Hours / Year = [ replace the Year with its equivalent in Hours ]

204540 Watt Hours / [ 8766 Hours ] = [ Hours divided by Hours = the units cancel out ]

204540 Watt / [ 8766 ] = 204540/8766 Watts = 23 1/3 Watts

Or generally the rule is, 8766 Watt Hours / Year = 1 Watt



What happened here, we did the exact same calculation but backwards...

In the forward direction, this would mean, that a 23 1/3 Watt lamp working all the time would use the same amount of electricity over a year. That is indeed correct :

23 1/3 Watts * 24 Hours / Day * 365 1/4 Days / Year = 204540 Watt Hours / Year = 204540 Watt Hours / Year

Ya'll lost me.  But that is what I get for not going to college/University.

Ya'll lost me.  But that is what I get for not going to college/University.

What do you know?
It's basic arithmetic.

I'm also really bad with math lol.
I live in Ontario Canada where the cost of electricity has been going up twice a year, Seems when we save more energy, they jack the price up because they aren't selling enough electricity so I have given up lol. As a matter of fact its rising another $3 or so this month. Looks like when i move to the country, i'll be getting off grid options!

The power company does want users to save energy. One reason is, electricity usage grows over the years anyway, and the grid have to be upgraded over time to handle the growing load. When users save energy they slow down this grow, and to the power company this means, that they can postpone expensive upgrades to powerplants, transformers, power lines and so on

I would hope that the money is going towards electrical upgrades etc. The skyrocketing cost has become a top issue here for years now. Currently the average home will see around 30$ more on their bill as rates have just increased May 1st

I would hope that the money is going towards electrical upgrades etc. The skyrocketing cost has become a top issue here for years now. Currently the average home will see around 30$ more on their bill as rates have just increased May 1st

What is the $/KW price? It is about $.125 Per KW here.

Summer (May1 to Oct 31st)
Off peak (7pm to 7am) is 8.7 cents per kWh
Mid peak (7-11am & 5-7pm) is 13.2 cents per kWh
On peak (11am - 5pm) is 18 cents per kWh

Weekends/ Holidays
8.7 cents per kWh

Winter (November 1 - April 30)
Off peak (7pm to 7am) is 8.7 cents per kWh
Mid peak (11am - 5pm) is 13.2 cents per kWh
On peak  (7-11am & 5-7pm) is 18 cents per kWh

My wife bought some LED bulbs, which cost about 10 bucks each in the supermarket.  One of them stopped working after a month.  No problem, they have a g'tee for 5 years.  Except, who keeps supermarket receipts for 5 years?

Anyway, I hate LEDs in the house.  Unshaded bulbs leave an after image on my retina even if I am not looking at them directly.  Also, especially with torches, the light is bright but you can't see any detail:  for example trying to read the specs engraved on an automotive bulk, or the serial number etched onto a plastic back panel.

Perhaps it is my age, but I like the crisp sharp vision you get under HPS street lamps, and I hate the HID car headlamps.  There is a good reason for the latter.  The human eye recovers much more quickly from the dazzle of a warm light than a cold light.  Back in the 70s or 80s all the cars in France had bright yellow headlights.  No dazzle and they looked way cool (no pun intended).

I've slowly let them in myself...
2 Philips A19 8.5w 2700K LEDs are the only ones in current use and they're great for what they are, though the color is a little drab, arguably worse than a lot of CFLs, but OK for the hallway lights they're in.  I had some "Designer's Edge" 3w 6400K PAR30s in use but took them out of service after a few years.  They date to 2011 or so, pretty primitive by today's standards and they were never that bright to begin with.  I also have this "Firefly" LED PAR20 lamp that looks like something NASA would build, it's a 9.5w 40w replacement but has horrid 60Hz flicker I can't stand.  (linear magnetic ballasted fluorescents don't bother me at all though).

Mostly still CFLs in use, (2700K, 3000K 5000K, 6500K, not depending on application, just what I bought and installed) though as they die I think I'll go LED, probably 5000K daylight. Or if I get some LEDs cheap I'll convert everything.  Even the little places like the refrigerator bulbs will get LEDs eventually, or at least that's my plan. 

Linear fluorescents, though?  Not unless the ballasts fail, then I might go with LED tubes.  But I like my magnetic T12s too much to replace them.  F32T8s, maybe, also as they die.