Shooting on location indoors - power considerations

[sbryan]

Just wondering what I need to know for running a three point lighting system in a home. I'm going to be using a 650W, 300W, and 150W Tungsten light.

I suppose I should be running extension cords to the kitchen because it normally has 20 amp circuits as opposed to 15.

I'm new to the lighting lexicon so forgive me if I phrase this incorrectly, but how do I know how much wattage I can pull from a circuit safely?

For the purpose of lighting for video, not building a home, how do watts, volts, and amps relate (primer would be helpful)?

What instruments should I acquire for testing?

How do I employ practical lighting? You can use a 100 watt bulb in a 60 watt fixture, but not a 60 watt bulb in a 100 watt fixture? Is that correct?

I've used china ball lights, reflectors, and other soft lighting until now so forgive me for my rookie status!

 

[Barry_Green]

Those three lights, together, only draw 1100 watts, or less than 10 amps; you should be able to run them on pretty much any household circuit (depending on what else is on that circuit, of course!) But even 15-amp wiring should handle all three.

As for how much wattage you can get from a circuit, 1500 watts from a 15-amp, 2000 watts from a 20-amp, which leaves a little to spare. But you really shouldn't push any one circuit that hard if you don't have to. Spread it out a little, especially in an older home as the wiring may not be up to snuff. Frequently the kitchen and bathroom will be on different circuits, so you can run a cord to each and have a good measure of peace of mind that you won't blow a circuit (unless someone turns on the microwave; some microwaves can use up most of a circuit by themselves!)

The maximum # of watts you can handle would be volts * amps, so a 15-amp circuit on 120v AC gives you technically 1800 watts. I round down to 1500 just for a margin of safety.

Make sure your power cords can handle the draw too; don't try plugging 1100 watts of power into a thin little extension cord, get a good 14-gauge or better cord to handle the draw. If your power cords get warm, you've got a problem and you need beefier cords.

As for practicals, don't exceed the rating on the fixture. So you have it backwards -- a 60-watt fixture can support a maximum of 60 watts; putting 100w in there puts you at a potential fire risk. A 100w fixture can support any size up to 100w, so a 60w bulb in a 100w fixture is no problem.

 

[modus]

Be concerned for the homeowner's stuff too. Always be aware of what else is plugged in elsewhere in the room. If an important-looking computer or other device is running off the same breaker you may want to either power it down or draw your power from another source.