We've all done it, be it blow drying our hair or plugging too many things into one socket. At some point in your life you've tripped a breaker. Now, imagine doing just that but you're in the middle of a shoot. Not only does it throw off your entire shoot, but it's embarrassing and can make you look unprofessional. Thankfully our friends over at Story & Heart have put together a helpful infographic to avoid this exact scenario.
Understanding the Basics
What does this mean exactly? First one has to understand how circuit breakers work, and there is some math involved. Most standard wall sockets in the United States are fixed 120V outlets. It goes without saying that this varies throughout the world, so be mindful of where you are shooting and adjust your numbers accordingly. Once you are able to identify what outlets are on the same breaker it's time to do some recon. Story & Heart states, "If you look at a breaker that protects the circuit of the outlets in the room that you're filming in and it says 15 Amps, you now have all of the information you need."
The Math
Now that we have all of the info we need let's look at our equation Power = Voltage x Current. 120(voltage) x 15(amp) = 1800W. The next step is to compare your lights and see what their wattage, for example say your lights are 400W, 400 x 3 = 1200W. This is less than 1800 which means you will not blow the fuse.
Try to keep this in mind when you are shooting your next project. Remember that you can unplug anything that is not being used as well, but just make sure you put it back how you found it. Have any other tips on how to not blow a fuse, let us know? Feel free to check out Story & Heart for other film related tips as well.
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This definitely holds true for modeling lamps and hot lamps because they are a constant draw lighting source. What I've never figured out though is if a power pack is labeled as 1000 watts, it might not be pulling 8 amps all at once. The capacitors are loading up that much amperage and releasing it when you fire your lights but the packs might be pull less amperage from the wall over the course of the 1-10 seconds it takes to refresh.
The average wall outlet in the US is 15 amps so if you have the chance to build out your studio, you might want to upgrade the outlets to 20 amps. You will also need 12 gauge wire and a 20 amp breaker for each outlet vs the 14 gauge wire and 15 amp breakers needed for 15 amp outlets. In my studio I ran each outlet separately so every power pack can be plugged into its own 20 amp breaker without any worry of anything overloading any one circuit. Obviously you would need to do a remodel to wire it up like this but it is definitely a nice thing to have. I remember when we first started Fstoppers in Lee's garage studio, we would film in the winter with space heaters on and blow the circuit all the time. Fun times
I always plug my packs into power strips, so if I do happen to blow something at least it'll be in arms reach. Back 100 years ago when I was assisting I remember people going on location with multi speedo 2400 and 4800 packs, they'd blow stuff all the time and we'd have to find a building engineer to get it going again, ugh total pain. These days so much less power is needed from lighting, my little dynalites and profoto compacts, have never blown anything.
So, around the old continent well have like 15amps x 230v, and that means 3450W. Kind of cool.
That's something i've allways been aware of, computer science and electronics at the university made me wonder what would happen if i exceed the power delivered by the socket or power pack.
I'm thinking about using a pure sine inverter to build my own power pack with a 12v battery, so i've been into this stuff...not to explode my lights and powerpack.
Not all fuses are 15A in "the old continent"
In my country, 10A is pretty regular. Brings you still to 2300W. But also 16A is possible, for the group wich containts your washing-machine for instance. Whoops out even 200W more than 3450W
While I appreciate the effort put into this article it's not actually very accurate because it fails to consider power factor. The circuit breakers that you speak of are rightfully called Thermal Magnetic Molded Case Circuit Breakers (Thermal-Mag MCCB's). They operate on apparent power not real power like you discuss in the article. For studio strobes the difference between real power and apparent power (power factor) is somewhere between 20% and 50%. Source: I'm a power systems EE.