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Power distribution problems
Hi gang… (cross posting in lighting design, hope no one minds)…
I need some help from those of you with more electrical knowledge than me (which won’t be hard to find, I’m no electrician)…
I need to figure out an easier way to split power distribution to instruments.
Here’s the deal… it seems that lately we are tripping breakers left and right when shooting on location. For smaller shoots we usually travel with a few tungsten instruments, but lately we have been shooting in some larger venues that require us to break out the daylight gear. For those, we usually use two 1200w HMIs, one 800w Joker-Bug, and a few smaller instruments.
It seems that no matter how careful we are, and how much we try to spread out the power, we end up overloading a circuit and tripping a breaker somewhere.
Now, I know the right way to do this… carefully plan the location, find where all the outlets are, get with the building engineers to determine where all the breaker boxes are and what breaker goes where, etc etc. But in practicality we usually can’t do that. These shoots are very run-n-gun.
Some examples….
Once this week when shooting promos in a TV studio, even though were were told where to juice from, one single 1200w HMI tripped a breaker that shut down all the computers in their weather department. Not good. It took them fifteen minutes just to find an engineer who even knew where the breaker box was.
The next day we were shooting a political commercial in an old church, and kept tripping breakers even though we were snaking cable and running instruments to outlets on multiple floors. In a 100-year-old building you can’t be sure that the wiring plot makes any sense. No one from the church working that day knew where their breakers were either… we just had to search until we finally found the boxes.
Couple of weeks ago in a car dealer’s showroom we tripped a breaker that shut down computers in the accounting department in a completely different part of the building. Who is wiring these places?
And yes, these are very low-budget shoots so we can’t afford a genny.
So… speaking just off the top of my head… is there such a thing as some kind of an electrical gadget that one could, say, plug into a regular Edison outlet and it show you what kind of load is already on that circuit?
Or any other solutions that anyone has to suggest?
Thanks,
T2
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Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com
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16 Replies
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Todd,
You must estimate power use at 18 amos for a 1200w hmi and 12 amps for the 800 Joker. This is the amount of power it takes to strike the units.
1200’s are problematical in practical use, whereas the 800’s which put out the same amount of light (although in a slightly smaller pattern) make life a lot simpler. They are also less weight and bulk. I highly recommend them for the type of location work you describe vis a vis the 1200’s.
When splitting power on a real location, even if you are very careful and logical you can still get skunked, as you own experience confirms. Even modern, high end buildings can be wired in a nonsensical way and codes do differ from jurisdiction to jurisdiction.
Here’s a few guidelines though; a quad box (four outlets in one box) on the wall is supposed to be a dedicated circuit and most times is. Bathrooms and kitchens are very likely separate circuits from others.
When I shoot in an unknown location, I always ask about the location of the fuse box. You’d be surprised how often folks don’t even know where it is and it’s best to find it in advance and inspect it to give you some idea of how many circuits are available, how they’re identified (if at all) and what sized breakers (or fuses) are in place.
If necessary you can always turn circuits off to determine where they come out in the set, although obviously you don’t want to turn folks computers off with out warning. For that matter, in a business environment, I always ask people to backup what they’re working on in case we happen to overload a circuit and blow a fuse.
Finally, if you are committed to using the compliment of 1200’s and 800’s as you describe, plan to bring plenty of extension cords to reach far away and separate circuits.
Hope some of this helps.
JS
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Hi John…
Thanks for the (good) tips… unfortunately those are mostly the things I’ve tried already.
Changing my instruments isn’t really an option right now. I’d love to have a truck full of Joker-Bugs, but at $6500 a piece (or thereabouts, the last time I checked), I can’t afford to get any more at the moment. I think the 1200s that I have must not pulse that hot when they strike as I have never had any problem with them on a 15amp breaker as long as nothing else big is on the same circuit. The Joker alone is usually not a worry.
Seems that most of the buildings that I run into aren’t wired anywhere near the way they are supposed to be. That includes my own facilitiy, where I swear the electricians must have been drunk when they built the place. In one section of my building I have FIVE quad boxes on one 15amp breaker… in another, there are SEVEN four-bangers on one. Our wardrobe/prop storage room is on the same breaker as the lobby, even though they are a great distance from each other and even on different floors. And it’s not some retrofitted nightmare, it was a brand-new building when we moved in. Sadly it seems to be just about par for the course, at least at the places we go.
We do always ask on location where the breaker or fuse box is… but 9 times out of 10 they just look at us blankly as if we had asked them to explain the pythagorean theorem. When we do find it, breakers are hardly ever labeled, and most of these locations are working businesses still in action so we can’t really start flippin’ them to see what’s what. Even on the semi-rare occasions that we do rent an entire facility as a shoot location (church or school or restaurant or whatever) there is still somebody invariably there trying to do some work, usually on a computer.
Ok, now I’ve moved into whining mode. Sorry about that, it’s just frustrating.
T2
__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com
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It appears the name of the gadget you’re looking for is called an ammeter. https://en.wikipedia.org/wiki/Ammeter
I did a quick search and they seem cheap, so that makes me skeptical it’s actually the correct gadget.
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I called my grandfather. He’s a retired electrician: Please see if this link works (hope it’s what you’re looking for). I searched Home Depot for “clamp meter.” https://www.homedepot.com/webapp/wcs/stores/servlet/Search?keyword=clamp+meter&langId=-1&storeId=10051&catalogId=10053
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Yes, a clamp style ammeter is the appropriate tool to read the current load on an electric line. The problem is that the clamp must go around the wire carrying each hot leg that you want to read. This is practical with banded feeder cable, but impossible to do with wires bunched together inside a conduit in a wall. There rarely is enough room to use it inside a fuse box either (Danger Wil Robinson!) so your theory is correct but the implementation is not. Sorry. There is no easy way to find out the load on practical circuits in a house or office, the best you can do is survey the situation and make an educated guess.
JS
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Hi Richard…
Thanks for your reply, and I really appreciate you taking time to call your grandfather. That was above and beyond the call.
John beat me to the punch, though… but he’s right, that gadget unfortunately won’t do what I would need it to… not without hacking into walls and conduit, etc., plus it doesn’t solve the problem of easily knowing what circuit goes where, which breakers feed each outlet, and such.
I guess I was looking for some kind of “MiracleMeter” that one would plug into an outlet and it would analyze what’s going on with a particular circuit, what loads are already present, etc. Oh well… I don’t think the tool that I need exists, outside of say some kind of sensor gadget in a science fiction movie.
Much thanks, anyway…
T2
__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com
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In order to use an ampmeter, you must first locate the box and then identify the circuits. You can, however, buy a device that plugs into a wall outlet and sends a signal down the wire. You then pass a detector over the breakers and that will indicate which breaker the outlet belongs to. This is out of the question in Todd’s situation.
When we’re stuck with the questionable amperage, we try to pull it off with fluorescents. That doesn’t work when traveling.
Without going to a more efficient light like a Frezzi or a Joker, Todd is in an almost impossible position.
We have all of our impoetant computers on battery backups. Too bad about the weather thing. That must have been a panic filled moment. I keep laughing about it because it’s happened to us a few times when we wrwe assured that the circuit was clear.
Steve Wargo
Tempe, Arizona
It’s a dry heat!Sony HDCAM F-900 & HDW-2000/1 deck
5 Final Cut (not quite PRO) systems
Sony HVR-M25 HDV deck
2-Sony EX-1 HD . -
Actually, Steve… that’s kinda interesting. I wasn’t aware of a device like that. It wouldn’t solve all my problems by any stretch, but could be a tad useful.
It’s not really an impossible situation, at all… just a bit inconvenient. I’ve yet to be in a situation where we absolutely couldn’t use the instruments we have… it just takes a bit of tiresome trial-and-error (and often annoying people) that we would like to do without. I’m big on convenience.
I’m probably stuck with the instruments I have for now. I can’t buy more Jokers unless I were to sell the 1200s… just can’t justify the cost. It’d be nice though… almost as much light with a head half the size and a ballast probably a quarter the weight. Wouldn’t have to lug around as many bigass junior stands, either. Sigh… maybe next year.
I didn’t sweat the weather thing at all, was a bit amused myself… especially since we were there shooting promos for the weather team… and using their suggestions as to where to juice from…. haa.
T2
__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com
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No worries.
I have another idea. In your system, you have several known factors: namely your lights, and you know the circuit breaks at 15 or 20 amps. It’s relatively easy to measure the volts, and then do some math. The hard part is the actual formula. Anyway, I have an email into my cousin, a mechanical engineer who works with a brilliant electrical engineer. Keep your fingers crossed!
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The actual formula is the easiest part.
Watts = volts x amps, or
amps = watts divides by volts.
The hard part is knowing which plugs are wired to which breaker and what else is using power on that breaker. This is where good street sense and a logical mind become your greatest assets. Don’t panic, find out where the fuse box is, try to seperate the usage to different circuits and observe which lights go out when you blow a fuse (breaker), This will tell you everything you need to know.
JS
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