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Determining Available Power

Published : 6th Dec. 2006

I'll be happy to move this to a different discussion list, as it's filled with a number of amateur questions.

In the mean time –

What's the best way to determine available power on a circuit? I do a lot of news/doc shoots using available power in locations where it's difficult to determine what circuits are being shared by whom, and in some cases need a building supervisor to access breakers. Is there some sort of a meter that can tell you the available power on a circuit by doing like a split-second draw? As a general rule, I use a kit that uses about 1650, but have connected closer to 2,000 in certain cases. Recently I forced the breaker when I turned on about 1,800 in a small office that was on the same circuit as 2 other offices. This was a mistake and I won't be pushing that high any time I'm unsure. Besides going to the breaker box and actually testing, is there anything else I can do to check what's available?

And in case anyone is curious, these larger wattages on small doc/news shoots are because I tend to prefer using a combination of ND and/or shutter speed to shoot wide open on 1/2" or smaller cameras. Also occasionally like to use windows and match that exposure with key if it's a bit overcast and I can get away with it.

Jim Eagan
NY shooter/editor


Jim Eagan writes :

class="style15">>>In the mean time - What's the best way to determine available power >>on a circuit?

The only way to determine the available power is to read the rating on the circuit breaker for that circuit and then use an ammeter to measure the current already being drawn through that breaker.

For example, if the circuit you want to use is rated for 20amps, and the draw or load on the breaker measures 8 amps, you've got 12 amps available.

I do a lot of news/doc shoots using available power in locations where it's difficult to determine what circuits are being shared by whom, and in some cases need a building supervisor to access breakers.

Is there some sort of a meter that can tell you the available power on a circuit by doing like a split-second draw?

Sort of, but only by tripping the breaker. It's essentially a device for testing breakers.

Brian Heller
IA 600 DP


class="style15">>>In the mean time - What's the best way to determine available power >>on a circuit?

What say the reg laments in your country? Here, in Spain, you know you will never get more than 7 Amperes or 15 from the type of the socket.

That's one of my restrictions I establish to my alumns when they plan to shoot on location: count the number of sockets and see what type they are.

Paco Rosso
www.pacorosso.com
Luz, colour, fotografía.


Jim Eagan writes :

class="style15">>>In the mean time - What's the best way to determine available power >>on a circuit?

If you can get access to the buss bars you can use a clamping ammeter, which scissors around a single conductor and reads the current flowing through it. Or you can sometimes scissor it around the wire coming from a breaker, but it depends on how old the box is (older usually is easier.)

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614


>>Jim Eagan writes:.

>>In the mean time - What's the best way to determine available power >>on a circuit?

>Brian Heller writes :

>>The only way to determine the available power is to read the rating on >>the circuit breaker for that circuit and then use an ammeter to measure >>the current already being drawn through that breaker.

Greenlee and others make circuit breaker tracers. You plug a small generator into a given outlet, then go to the panel box with a tracer wand that has a tone that tells you when you're holding it over the breaker associated with the outlet you're sensing. A fairly short amount of time spent in an office or home with an assistant plugging the generator into outlets and you or your gaffer tracing breakers and keeping track of which circuit feeds which would let you know which outlets are on which breakers. If necessary you could string an extension cord or two and move the locations plug-in electrical lights etc. around so you had a circuit or two that was all yours. That way you'd know you had all the amps available from a given breaker.

I have a Greenlee I use from time to time, it takes a little practice to get real quick at tracing breakers but the gadget really works well. Mine came from Lowe's and I think I've seen them at Home Depot. Any general electrical supply house probably has, or can get them

Hal (the electrical bloodhound) Smith
Edmond, OK


Thanks for the help. I've heard about these before, but they were (mistakenly) referred to as "amp-meters". I see Radio Shack carries AC/DC ones for $20. I was told in a lighting class that a jolt of 10-15 amps can be lethal. Are there risks I should be aware of? And is a volt-meter or multi-meter at all helpful in this scenario? A friend of a friend is an electrician, so I'm probably going to have him show me the procedure here since I'm not following it all (what are buss bars?).

Jim Eagan
NY shooter/editor


Jim,

If you're replying to my post, I am not talking about a volt and amp meter. The Greenlee generator generates a small signal (like a small radio transmitter) that travels back over the location's electrical wiring to the panel box where it can be picked up with a receiver probe. The only direct electrical contact is the generator and it's as safe as any UL approved electrical plug. Obviously a big advantage is being able to trace circuits without turning breakers on and off.

I beg to differ with your lighting class. The amount of current that can kill you is measured in THOUSANDTHS of an ampere!!! The voltage available to "push" current through your body is what sets up lethality. In general, somewhere around 70 volts AC or DC is the maximum that is really safe to get in contact with, it'll bite you but won't kill you. That is why the National Electrical Code has a different set of rules for lower voltages - they're not as apt to be lethal. If your skin is cut open, like in surgery, I've heard that even 6 volts or so can be a problem. In an operating rooms the maximum allowable amperages are in the millionth of an amp range.

If you do want to measure voltage and amperage with a meter, make certain you use a meter and leads that have UL/CE compliance labelling for at least 600 volts and read the instructions twice. Stick with professional grade meters like Fluke, Wavetek, Greenlee, etc., they've got reputations to maintain - almost every electrician, engineer, and technician of my acquaintance (including myself) use Fluke's gear. In my day business (radio engineering) I have to measure voltages in the high thousands from time to time. The probes I use are rated for at least 25,000 volts - and I've got a lot of experience and training over the years in how to work safely in equipment with 4 and 5 times what is used in an electric chair.

Old school electricians and gaffers will tell you that 440 AC is the worst to get in contact with, you've got a better chance of not getting hurt by lower voltages, and muscle contraction will fling your hand and arm away from higher voltage circuits. So 440 is the range where you stay and fry for a bit longer. But don't go licking fixture sockets to see if they're hot, assume anything over 70 volts intends to kill you. :D

Hal (been there, done that, OUCH!) Smith
Edmond, OK


Without tracing circuits, either off/on with a plugged in light or buzzer, or using the circuit chaser thing which almost the same, but you don't have to turn circuits on or off, There isn't a way to tell. Still how will you know what circuit that fridge is on, without testing it?

Personally I think it is important to check both outlets of a duplex receptacle as sometimes they are two different circuits, which can be nice.

I've a box I built that separates the legs of a 220/240 outlet. I've found this very useful when shooting in Manhattan and the only decent/non lethal looking outlet is an air conditioner outlet. Air conditioner outlets usually aren't shared, so once they are split by my box into 110/120 I've got two separate circuits with 20 amps each. Of course this only works in the U.S., and is of no help if you need the air conditioner running.

I've also found bathroom outlets tend to be isolated to the bathroom, but are usually 15 amps.

Again the 224/240 splitter only works in the U.s., because in the U.S. the power scheme is 110/120 and by using two different legs we get 220/240. In Europe this sort of splitter will not work.

Steven Gladstone
New York Based Cinematographer
Gladstone Films
www.gladstonefilms.com


Hal, the Greenlee sounds very helpful in some but not all scenarios. That would be good to use if I had the time/ability to reconnect components on a line. Usually I'm in a situation where lets say I've got 45 minutes from location arrival to setup. Usually I do not know where the breaker box is, people working at the location do not know where it is. And most equipment sharing the circuits cannot be re-connected to a new circuit as that would disrupt their work (on computers, etc.). I will keep the Greenlee in mind (is it pricey?), but for the time being, an ammeter sounds like it will let me read the available power as long as I am able to locate the breaker box. Once I know available, I can determine lighting scheme with no worries about overload.

This is slightly off topic, but I've also connected out of the more expensive battery-backup surge protectors that shut down after say 750 or 1000 watts were connected. Some apparently have internal breakers that shut off on a given draw. I found them more annoying than anything else. On another occasion, without watching where everyone was hooking in, we had about 2,500 going on one circuit and nothing tripped. But within a few minutes I checked the lines and they were very hot.. In that case, I suspect the breakers were faulty and that could have been a disaster.

Jim Eagan
NY shooter/editor


Jim,

The Greenlee's go for about $65 - probably one can be found cheaper in an eBay store. UPS's seem to be getting cheaper and cheaper, they've become a computer commodity and most people figure cheaper is better.

Hal (don't give me cheap, give me good) Smith
Edmond, OK


>>Greenlee and others make circuit breaker tracers. You plug a small >>generator into a given outlet, then go to the panel box with a tracer >>wand that has a tone that tells you when you're holding it over the >>breaker associated with the outlet you're sensing.

This assumes that the plugs are wired correctly. If not, you could be sending the signal over the neutral. Does the device has a possibility to switch prongs to send the signal across?

If of course the signal is sent across both live and neutral, then my question can be dismissed

>>I was told in a lighting class that a jolt of 10-15 amps can be lethal. Are >>there risks I should be aware of?

Yes. 30 milli-amps can kill you already.

cheers


Martin Heffels
/filmmaker/DP/editor/
Maastricht, the Netherlands


>>This is slightly off topic, but I've also connected out of the more >>expensive battery-backup surge protectors that shut down after say >>750 or 1000 watts were connected.

Speaking as an IT tech, if I found you plugging anything into a UPS box or circuit that I had not vetted first you would find your butt on the street before you could blink. Those units are designed to protect the computer equipment connected to them. Plugging lights and other strange devices into them is a Bad Idea.

Marty Brenneis
Industrial Magician


Jim,

The rule of thumb that I use is 1000 watts per circuit [120v] if it's not a kitchen or industrial (machine) type place (usually 15a to 20a available when clean). If it is, I'll push to 2000w as these circuits are rated at 30 and sometimes 100 amps.

Jared Hoy
Gaffer || BBE
Los Angeles, CA


Martin Heffels wrote:

>>This assumes that the plugs are wired correctly. If not, you could be >>sending the signal over the neutral. Does the device has a >>possibility to switch prongs to send the signal across?

Not the inexpensive versions.

>>If of course the signal is sent across both live and neutral, then my >>question can be dismissed.

Like lots of other things, manufacturers make different versions of their products, including the Circuit Breaker Finder -- a reversed neutral being only one problem that inexpensive finders can't handle.

In a normal sized home with standard wiring and appliances the "shirt pocket finder" works pretty good. In larger homes with sub-panels, surge-protectors, and automated appliances using the house wiring to "talk" to each other, it does not do so well. There are more expensive versions that do work better in these environments, but no version is foolproof.

In a larger office building, manufacturing or industrial site, with, for example, a lot of motor noise on the lines forget about it.

In those situations, do yourself a big favour, get in touch with the house electrician and give him a case of good beer. For instance, you may not overload any individual breaker, but the cumulative load created by loading up several individual circuits may overload a much larger breaker downstream, thus disrupting a lot more than your filming.

One other thing, finding the breaker before it has tripped is of little value for film work. Unless you remove the panel cover and measure the loads with an ammeter, it's of little value. These devices are intended to help an electrician locate a breaker in order to shut off power before commencing work on that circuit. Finding and resetting a tripped breaker is rather elementary.

BTW, there are any number of excellent "do it yourself" guides to home wiring that explain how household wiring functions. There are also any number of technical school textbooks that do a more thorough job. I'm not suggesting that anyone not familiar with electricity start re-wiring their homes, but a basic understanding of what's going on behind the walls would help immensely in these discussions.

Brian Heller
IA 600 DP


Marty, good to know. My mistake of plugging into the UPS was not as bad as it sounds, since I did it in an office I work at, and was able to shut off any equipment that was connected. And if I remember correctly, this UPS had 1k being drawn between 2 500 lights. It beeped then shut down. No fuses went, just simply needed to be restarted. And not to get farther off-topic here, but how do surge protector strips and UPS boxes affect the amperage? Is there an additional draw due to the splitting?

Jim Eagan
NY shooter/editor


The surge protector strips don't draw any extra current, so you can just sum the current of all the things plugged into them. HOWEVER, most of them have internal 15A breakers or fuses, so they will pop the internal fuse with a 15A load even if they are plugged into a 20A outlet.

This is a big problem with a particular craft services organization that keeps plugging two coffee makers into one power strip and complaining that their power is no good. Coffee makers pull a surprising amount of current.

UPSes come in two flavours... one is a standby type, which has a pass-through mode where power from the wall is directed to the output until it detects power loss, and then switches over to internal inverter. The other is an online type that runs on inverter all the time.

If you plug a load into the same outlet as a UPS, which has a high starting current draw (like some HMI ballasts), a standby UPS may see enough of a line sag when the lights are turned on for it to go into inverter mode and start beeping briefly. You can ignore this.

Don't plug anything into the output of a UPS. Some online UPS units will go berserk with highly inductive loads (like HMI ballasts). Just don't go there.

So, in short, add up the currents of everything together and make sure it doesn't exceed the current at the outlet. If you can be sure that nothing else is on a circuit, you can assume that an outlet with two parallel blades can produce 15A and an outlet with a T-shaped blade can produce 20A. If you don't know what else is on the circuit, it's best to spread the loads around as much as possible. You can buy some circuit tracer gadgets that will help you determine what outlets are on what breaker; gaffers should have one in the kit. Often in a documentary situation you don't have the time to carefully lay stuff out, though.

Scott Dorsey
Kludge Audio
Williamsburg, VA.


>>the Greenlee sounds very helpful in some but not all scenarios.

I haven't used it but have worked with electrics who did & found it immensely valuable. Your "45 minutes" scenario is on the margin, possibly.

But the first time you get that "surprise where'd the light go ?" in the middle of a take, well......

Plan B, start switching off the office's breakers and see who complains

Sam "the circuit with the coffee machine is sacred" Wells
film/.../nj


>>Coffee makers pull a surprising amount of current.

I was doing outdoor sound for a Detroit Red Wings/Outback Steakhouse golfing benefit when one of the event coordinators came running up saying that they were having electrical problems and could I help. When I followed her to the food preparation tent I found a huge diesel generator running that was there to supply power.

The problem?

No power distro system. Instead they had a 15amp power strip plugged into the "courtesy" outlet. From there a web of six orange extension cords ran to an area where there were more power strips. Each of those had 5-6 DEEP FAT FRYERS plugged into them so they could make their bloomin' onions.

That was incredibly 'special' moment

Jacques Mersereau
Video and Performance Studio Coordinator
Digital Media Commons
Duderstadt Center, Room 1356
University of Michigan
2281 Bonisteel Boulevard
Ann Arbor, MI 48109


Steven Gladstone wrote:

>>...I've a box I built that separates the legs of a 220/240 outlet.
>>I've found this very useful when shooting in Manhattan and the only >>decent/non lethal looking outlet is an air conditioner outlet....

I've made a couple of similar splitters, one with a stove plug (2 - 50 amp circuits) and another with a clothes drier plug (2 - 30 amp circuits.) These are great in residences, but in offices you'll have to run some stingers down to the snack room/kitchen to plug into the electric stove outlet.

But for these quick in and out setups, I'd first locate the breaker box for that floor. The breakers are supposed to be indexed on the chart inside the door, which will help you identify what circuits are available in the room you are using. If you see a breaker shared by two rooms, just be sure you avoid running a stinger to the second room; run it over to another room.

Also, you probably realize that a receptacle on one wall is often tied to a receptacle on the other side of that wall in the next room, so if you are unable to trace the breakers by looking on the index chart, just be sure you don't run cables to both of these receptacles. You're usually safe by skipping the adjacent room and going for the next one.

(Jim--Buss bars are heavy copper bars that breakers are attached to.
They are fed by the incoming heavy cables supplying the box. Reading the current by using a scissor type ammeter around the buss bar (or around the single cable feeding it) would tell you the total current being drawn on that leg. I hadn't read your original post, so didn't realize that this would be impractical for your needs. This is good mainly when you are doing a tie-in.)

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614


So going through these responses, I can see the meters and tracers being helpful in some cases. But as a general rule of thumb for "quick" location shoots, using 1k max on an office or home circuit is a safe place to start. And if you know you'll need more, bring a generator? As a doc/news shooter, sometimes there just isn't the time to go to the breaker box, taking readings, etc.

Is it bad practice to go to a location, mention to everyone else possibly on the line that you will be drawing 1k in a few minutes, please save any documents you are working on. The 1k draw most likely won't trip anything, but if does, people will have been warned ahead of time.

Or instead, would it be safer for me to find more efficient lights (like the newer gas filled ones) and reduce consumption to about 500, where I can safely plug in to just about anywhere. And I'm not a huge fan of using fluorescents, but I suppose that's another option.

Jim Eagan
NY shooter/editor


>>Plan B, start switching off the office's breakers and see who >>complains

I've lit lots of sit down interviews with a 'plug in the wall' package.

Given that there are usually time constraints that prohibit exploring which outlet is on which breaker, and that even mapping the circuits won't always tell you what kind of load is on each circuit, here's what I usually do.

First thing, find out where the breaker box is. It's a lot easier to find before people are panicking. When you find it, make sure you can open it - sometimes it's locked. Look at it, and see if there are 15 or 20 amp breakers. The age and condition of the box will tell you something about the age and condition of the rest of the location. If the condition of the wiring looks old, then you may want to reconsider what kind of lights you'll use. If you discover fuses, you may want to send someone out for spares if there aren't any nearby. Warn the rest of the people working in the space (especially if it's an office) that they should save their work....

Then, utilize the circuits that are most likely to be independent from other outlets. The two places that usually have the most power available are the kitchen and the bathroom. A toaster can draw 8 or 10 amps by itself - coffee maker a similar amount.

Unplug the coffee maker/toaster/whatever, and plug the biggest light you plan to use into the outlet where the appliances were plugged in. This gives you the best chance that your largest load (say, 1200w HMI which draws about, well theoretically 10amps, but realistically a bit more)will not trip a breaker. If you're using several smaller units, you can run an extension cord from the outlet to the set, and then use load up that circuit to the equivalent of the toaster/microwave/normal kitchen load. For instance, two 650watt lights is 10amps, roughly equivalent to the toaster. Distribute the rest of the load (presumably smaller lights) using different outlets.

Hallways, especially in hotels and usually in offices, may have independent circuits. This is the place where the vacuum cleaner/floor polisher/etc will be plugged in at night. I try to avoid using outlets that are already heavily used, and go for those that are more isolated, even if it means more extension cords.

When a breaker does trip, the instinct is to reset the breaker as soon as possible, especially when people are complaining that they've lost power.

Resist this impulse - don't reset it right away. Use the opportunity while the power is off to find out what other outlets share the same breaker as the tripped outlet you've plugged your light into. Take a small light or one of those 'plug in circuit testers' and find out what other outlets are still on, and which are off. Redistribute your load (move one or two of your small lights that went out) to an outlet that is still on. Then reset the breaker. Since you've already found the breaker box, and know that you have access to it, you know that you can do this quickly.

The rest of the advice (don't plug things into UPS's, get a circuit finder) sound good - good luck Jim!

Ted Hayash
CLT
Los Angeles, CA


Thanks for the advice Ted, all very useful practices I will keep in mind for upcoming shoots. I should mention that I've shot perhaps 150 or more interviews in offices, labs, factories, and a few homes in the last couple years. It wasn't until the last few months when I've been using 1.5k -plus kits that I've encountered problems and thus realized I should learn more about power supplies.

Like Jared said, I've found that 1k is a very safe number and have never had a single issue with that much draw. I always do a cursory look around the location to see if there's anything else major plugged in nearby, air conditioner, etc. And I never put them all on the same wall-outlet... often will wire from different offices or at least from different outlet in same office. Anyway, my blissful ignorance is over and I feel lucky that there were no disasters. From now on I'll request from producer that I get a few minutes at start to check the breaker box, and if possible wire from clearly marked circuits (kitchen, etc.). This may sound very ignorant, but I feel a little disappointed with the current state of electrical power. In this age of technology, it would be nice if there were "smart" outlets that could tell you how much power is available. But until then... will deal with the workarounds.

Jim Eagan
NY shooter/editor


>> In this age of technology, it would be nice if there were "smart" outlets >>that could tell you how much power is available. But until then... will >>deal with the workarounds.

Oh that would be complex. You would need to have a set up where the breaker was sensing how much current was being drawn as you would want to know the draw of all the outlets on that circuit/breaker. Then you would need some way to transmit that info to the outlet, and a display in the outlet, making all this simple and fairly reliable equipment more complex, expensive, prone to failure, and insurance claims as people would start to overload outlets because they read it once and it said 1,000 watts so they figured they could just keep putting 1,000 watts into all the outlets.

True story, I have a friend who called me wanting to put more power into his apartment, and asked if replacing the 15 amp circuit breakers with 20 would be okay. After telling him no, it was dangerous and he could burn down the building, he kept asking but 20 is more than 15 wouldn't it work. Ten minutes later I finally made him promise not to try it.

By the way, I don't have any problem telling people to shut down their computer when I'm shooting interviews. I tell them the chances of anything happening are slight, but I don't want them to lose anything if it happens. People seem appreciative.

As far as shooting in office buildings, often times there are orange receptacles, which may be isolated, the IT person might know (if they aren't just graduated from the popcorn counter).

Steven Gladstone
New York Based Cinematographer
Gladstone Films
www.gladstonefilms.com


Another point that is sometimes forgotten is that the voltage drop increases as the load increases. A nominal 120 volt circuit may have the voltage vary considerably depending on what else is on the circuit and even the time of day. Even a 10 volt drop (down to 110 volts) will reduce the light output of a 3200K tungsten halogen lamp by over 20 percent, and the reduce the colour temperature by about 100 Kelvin.

Use an accurate AC voltmeter to verify the line voltage under load, and compensate accordingly. Avoid using circuits where the load may vary unexpectedly (e.g., a refrigerator or dehumidifier turning on), or you may see the light vary during a take.

During summer, "brownouts" may cause a considerable reduction in voltage, as power companies struggle to meet energy demands with high air conditioning loads.

John Pytlak
Eastman Kodak Company


I'm starting to realize why generators are such a common film tool, even when indoors. Does anyone have any recommendations on about 2k size generators? I was looking at the Honda ED2000i that seems conveniently sized and quiet. Is Honda a good brand? Any reason why I wouldn't want to use something like this on a shoot that will be drawing about 1,800 max?

Jim Eagan
NY shooter/editor


>>Any reason why I wouldn't want to use [a small Gennie] on a shoot that >>will be drawing about 1,800 max?

Hi Jim,

As I'm sure you realise, generators create a whole new bunch of problems. Say you're filming an interview on the 8th floor of an office building.

Where are you going to put your generator? Are you going to park it on the pavement and run cables down to it? I doubt you'd be allowed to do that. And there's no way you'd be able to run your generator anywhere inside the building.

Instead of spending your money on a gennie, I would recommend spending your money on more efficient lights so you don't need to draw so much power.

Best of luck,

Jack Kelly
London
Dir/Prod/Camera


>>And I'm not a huge fan of using fluorescents, but I suppose that's >>another option

Despite my aversion to discharge lighting, I made my peace with KinoFlos when necessary.

This was called "Situation Ethics" in the sixties

500 W Rifas can get the job done....also....

Sam Wells


Jack, this is true (although I could probably use the gennie next to a window). More efficient lights are probably a good place to start. Currently use a Rifa 500, Lowell DP, 2 Totas, and a couple Arri 150s. I suspect the best solution might be to get a rifa 250 to key, eliminate my indoor 1/8 ND, and go from there. There's something about using the bigger units with ND’s that I like though, it's interesting to layer them with a lower ambient fill and I can all sorts of nice effects. But scaling down is apparently the only option unless I have the time to deal with the breaker box beforehand.

Jim Eagan
NY shooter/editor


Jim Eagan wrote:

>> Jack, this is true (although I could probably use the gennie next to a >>window).

Not legally, and doing so would probably invalidate your insurance.

Perhaps you should consider bringing an experienced and knowledgeable gaffer/electrician with you on a few shoots until you get a handle on how to find sufficient power yourself.

Brian Heller
IA 600 DP


I think Jim has enough experience and knowledge, he is just facing the same situation that we face when we walk into a location, and there isn't time or the ability to shifting through an offices electrical box.

It would be nice to have the outlets be smart and tell us how much was left on a circuit, but such a system would be so complex and expensive, and in the end be unreliable I think.

I did a shoot in a conference room at a major drug companies corporate headquarters. There is no running to the box to check outlets, it just isn't happening without the building engineer. So you do your best, and in some offices I've seen outlets numbered, which has helped.

So we try to spread out the load. Jim a 1200 watt HMI will give a lot of punch for the power it uses, and shooting with natural light from windows becomes simpler then. I'm sure you know this, but it might be something to think about.

What about a DC driven HMI.

Steven Gladstone
New York Based Cinematographer
Gladstone Films
www.gladstonefilms.com


Right, I do a lot of shoots in labs, hospitals, offices, etc. and when I ask about breaker box and it always takes a good 5-10 minutes to find the person the knows where the breaker is, often it's a hike to get there, and often they want to supervise. On some shoots this is fine, but generally this is time out of the producer's day that they would prefer to be spending elsewhere. So I'm looking into lower wattage lighting plans for these shoots, perhaps by purchasing new lights, and also reduce my tendency to use ND’s or higher shutters indoors.

Jim Eagan
NY shooter/editor


Steven Gladstone wrote :

>>It would be nice to have the outlets be smart and tell us how much >>was left on a circuit, but such a system would be so complex and >>expensive, and in the end be unreliable I think.

You can always use a clamp-meter to check per phase what load you have, so you will have an idea what you will have left over. Of course it doesn't tell you which phase an outlet is connected to. but you could find that out by using a small light, like a 500W, and switch that on & off while checking the clamp-meter. To provide having a "hit" from a refrigerator switching on at the same time, you would need to switch the light on&off a few times.

Cheers

Martin Heffels
/filmmaker/DP/editor/
Maastricht, the Netherlands



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