Actual Amperage for M18?

T

tommygdawg

Well-known member
Hey all,

Pretty simple question here. Assume money isn't an issue (because, keepin' it real, aint no way I aint buying Chinese knockoffs), what's the actual amperage draw of the M18 with an 1800 watt bulb? According to the math, with a power factor of 0.98 and minimal to no line loss, it shouldn't draw anywhere above 15.3 amps. But I've seen some people say that it draws 20, while others say 15. What is the actual number? If it is 20 (or close to it), why is that number so high??

Now, the money part. If I was going to buy another HMI (genuine Arri or knockoff), would I be better served buying a 1.2k or getting a 1.8k and just using the 1.8k bulb when I need some extra punch (likely with a generator)? I really want to avoid generators as often as possible because who likes generators?

Thank you!
 
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I have had them pop 20A breakers.
Remember your stinger length and gauge will play a role as well.
They draw right around 19.5 amps.
You will also need a junior stand.
 
Also had M18(s) pop 20A breakers (120V 60Hz) so often utilize 1.8K/1.2K ballasts with 1.2K globes.

Never had a breaker pop with a 1600W Joker, but haven't used them as often as the M18, & never ran side-by-side tests.
 
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Roger that, thanks guys. I would assume the 1.8k/1.2k with a 1.2k globe would pull the same as a 1.2k ballast?

Any idea why the 1.8k pulls 19-20 amps (assuming no line loss)?
 
You can't really assume no line loss because line loss is almost always the culprit. That coupled with soft breakers and it won't hold.

Just avoid stingers with them and only use the head feeder and you'll be fine.
 
RyanT said:
You can't really assume no line loss because line loss is almost always the culprit. That coupled with soft breakers and it won't hold.

Just avoid stingers with them and only use the head feeder and you'll be fine.
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Thanks, Ryan. Just out of curiosity, do you tend to notice a 20ish amp draw with them too? I certainly would never expect no line loss, but would even a small amount of line loss account for adding an additional 3-5 amps beyond the 15.3 the math gives you?
 
Well, the basic math (which I'm still learning). 1800W/120V = 15A. With a power factor of .98 that would make it 15.3A. Of course there will be line loss and resistance and all that, but I guess I just didn't expect those things to account for going from 15.3 to 19.5
 
tommygdawg said:
Thanks, Ryan. Just out of curiosity, do you tend to notice a 20ish amp draw with them too? I certainly would never expect no line loss, but would even a small amount of line loss account for adding an additional 3-5 amps beyond the 15.3 the math gives you?
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Sounds right to me. 15.3 amps...

I just don't use stingers with them. Maybe a 25' or 50', but no more. Some breakers are soft and I think that accounts for most other situations...sometimes it's just a bit unexplainable. At that point I just take it down on the dimmer a pinch and my issues go away.
 
The reading was from my Fluke True RMS meter.

We ended up giving them their own 30a leg from a generator, but in the end I stopped renting the M18, and now rent the Joker 1.6K when needed.
 
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RyanT said:
Sounds right to me. 15.3 amps...

I just don't use stingers with them. Maybe a 25' or 50', but no more. Some breakers are soft and I think that accounts for most other situations...sometimes it's just a bit unexplainable. At that point I just take it down on the dimmer a pinch and my issues go away.
Click to expand...

David W. Jones said:
The reading was from my Fluke True RMS meter.

We ended up giving them their own 30a leg from a generator, but in the end I stopped renting the M18, and now rent the Joker 1.6K when needed.
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Thanks, guys. I'm in the market to buy a light, but unfortunately not at the price of a genuine Arri. It's too bad Joker seems to be the only that makes a 1600 (ie no one in China!). Also, please don't think I'm trying to contradict your readings, David. I'm just interested in understanding why it draws 19.5 amps. Ryan's idea actually seems like a pretty decent one, just keep an 1800 globe in the fixture and bump it down on the dimmer a bit.
 
It is always nice to have accurate readings. Especially when using power from a location. If I'm using location power I tend to check their breaker box to know what I have available.

I also have a secondary meter I purchased when I misplaced my nice $400 Fluke, and it works very well. It is a lower cost compact Fieldpiece SC260 True RMS clamp meter which is around $120. It doesn't have all the bells and whistles of my bigger unit, but it has most everything I would need. These things are big with the HVAC folks, and a handy tool to have in your kit. Just something to think about.

All the best!

Dave
 
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