School me on Metal Halide electricity use

[Reefing102]

So as some of you may know, I run metal halide lighting on my larger display tank. The one concept I have issues understanding is how the lighting electricity use is calculated.

So my fixture is 2 150 watt HQI bulbs with 2 150w electronic ballasts. So am I running 600W of power or just 300W? I don’t have a killawatt meter or whatever to measure it.

 

[blaxsun]

Probably 300 watts when they're on.

 

[DeniseAndy]

No idea, but my electric bills are high. I also run T5s and a chiller. Granted, our AC runs constant in the summer too.

I run 3 250w for a good 4hrs a day. Compared to the rest of my home, they add to the bill, but not that much.

 

[Bpb]

That’s 300 watts.

 

[Reefing102]

Thanks for the responses so far! I run my halides 7.5 hours a day. No heat issues. No chiller. I’m glad I’m only at 300 watts and not 600

 

[ZombieEngineer]

It depends on the efficiency of the ballasts you have. Worst case is 88% efficiency. Maybe 96% if you got a really high end ballast.

Wall Power = lamp Power/ efficiency

So for your case it's 300W / 0.88 to 300W / 0.96


So between 312 and 341 watts.

If you plug them into a wattmeter like a kill-a-watt or an apex EB832 outlet, you can get an exact number.

 

[blaxsun]

Waiting for the inevitable "metal halides are totally worth it" comment...

 

[YOYOYOReefer]

your power meter doesnt care what kind of bulb it is
one 150 watt mh fixture burns the same as one 150 watt t5 or one 150 watt led, or one 150 watt heater... all the same a watt is a watt.

 

[ZombieEngineer]

your power meter doesnt care what kind of bulb it is
one 150 watt mh fixture burns the same as one 150 watt t5 or one 150 watt led, or one 150 watt heater... all the same a watt is a watt.

That is not correct. All of those are the power consumption of the bulb itself not the power draw from the wall. The actual draw is

Bulb power / ballast efficiency.

This varies depending on technology and quality of ballast. Magnetic MH ballasts are the worst at 88% and LED power supplies are the best around 98%.

 

[Reefing102]

It depends on the efficiency of the ballasts you have. Worst case is 88% efficiency. Maybe 96% if you got a really high end ballast.

Wall Power = lamp Power/ efficiency

So for your case it's 300W / 0.88 to 300W / 0.96


So between 312 and 341 watts.

If you plug them into a wattmeter like a kill-a-watt or an apex EB832 outlet, you can get an exact number.

Thanks! This is what I was looking for. I knew there was something out there. These are newer electronic ballasts but still “cheap” in comparison to other, I’m sure more efficient ballasts. Still even if it’s 341, that’s better than 600 lol

 

[YOYOYOReefer]

and if your really super concerned about 10 watt tops per fixture difference you might pick a cheaper hobby
all ballasts require some energy to work.

 

[ZombieEngineer]

and if your really super concerned about 10 watt tops per fixture difference you might pick a cheaper hobby
all ballasts require some energy to work.

Never said I was concerned about it. Just correcting your assertion that they are all the same. Most people do not understand that 150W bulb does not actually mean 150W.

 

[YOYOYOReefer]

its always a combo of the bulb and ballast when talking mh.
i run overdriven 400 radiums on pfo hqi ballasts.. s i forget but i think they draw about 450 watts or so , on eballasts same bulbs draw closer to the 400 rating ... but you cant do that with the redesigned radium bulbs only the old ones.

 

[Reefing102]

and if your really super concerned about 10 watt tops per fixture difference you might pick a cheaper hobby
all ballasts require some energy to work.

Definitely not. Was just trying to understand the concept. The effect the ballast may have had as I recalled seeing some really odd numbers and percentages and was wondering where they had come from. Thanks for all the help!

 

[YOYOYOReefer]

ya the HQI term causes some confusion , and people used to overdrive bulbs (on purpose) 250 on an M80 ballast or a 400 Radium bulp on a "son of agro " or "pfo Ballast , were what many people diy'd back when lighting was not so easy to find

 

[oreo54]

ya the HQI term causes some confusion...

Especially if you go to the original meaning .

Hydrargyrum quartz iodide (HQI) is a trademark name of Osram's brand of metal halide lamps[1] made for general floodlighting, arena floodlighting, shop and commercial and industrial lighting. Hydrargyrum is the Latin name for the element mercury. When heated, mercury vapour is created inside the lamp, and deposited when it cools.