Let’s *try* to understand ⚡️electricity⚡️ Part II
Last week I discussed volts, amps, watts, and resistance and how their relationship affects our lights on a circuit.
Today I’m going to give you practical tips that you can use on set when deciding how much power you’ll need to supply your lights. Let’s dive a little deeper into amps.
The amperage of a circuit is important to consider because all components of an electrical distribution system must have enough capacity to carry the current. If your cables are too small, they will heat up and could start a fire. Ain’t nobody got time for that.
To calculate the amperage of your lights, divide the wattage by your voltage. In the US on a household circuit, that would be 120V. For example, a 500W light on a 120V circuit pulls 4.2A. That same light on a 240V system would be 2.1A. Easy, right?
Well, if you’re like me and easily confused by numbers greater than 100, there is a quick way to do that calculation in your head. Instead of dividing by 120, divide by 100. Dividing by 100 over estimates the amperage and builds in a little buffer margin into your load calculation. This is known as the paper method. For example, that 500W light would be 5A. It’s always smart to factor in a safety margin. Most household circuits are 15 or 20A. Again, always over estimate your load. That way if a client plugs a laptop into your circuit, you won’t trip the breaker :)
Next week I’ll do my best to describe a real scenario of working on location and how I approach load balancing on house power.
The image above was relatively simple to light after we rigged our lights to the ceiling. Titan Tubes replaced the fluorescents overhead for an effect on cue. Crossfades played in the side offices, LiteMat 4 in the background, an Intellytech Mega LC over talent, a LiteMat 2L as the key with a bottomer to keep light off the cubicle walls, a couple Aputure MCs under the cabinet for a little extra 🤌 and as an eye light in the closeups.
HS Grace Martin
Tyler Kaschke is a freelance gaffer with a grip truck based in Lafayette, Colorado serving Boulder, Denver, Golden, Fort Collins, Colorado Springs and the Rocky Mountain region at large.
For more about understanding electricity and other set lighting tips, follow me on Instagram @colorado_gaffer