How do you determine if power outlets will support lights?

M

Mark-P

Well-known member
I am going to borrow an Arri lighting kit to use in my apartment to do some practice shoots. How can I determine if my power outlets have enough power to support the energy requirements of the lights?

Thanks!
 
Normal, modern apartment buildings will typically have at least 15a plugs and breakers as will a house. That's pretty much a given based on building codes. (Unless you live in an area without building codes and they do exist!). With older construction all bets are off and you have to do a little more leg work to verify what's going on.

Normal, modern commercial construction like offices will have 20a plugs and breakers.

For your reference, a 15a plug/circuit should normally support up to around 1200w load without too much problem--but of course your mileage may vary based on all the variables involved including the quality of the wiring in the walls.
 
Tungsten lighting is extremely power-hungry. On a 15-amp circuit you could use maybe two 650w lights, as long as nothing else is powered on that circuit.

For shorthand, a 15-amp circuit should support 1500 watts. A 20-amp circuit should be able to support 2000 watts. There's some margin of error there, but it's a shorthand rule that should give you some ideas.

Frequently bathrooms or kitchens will be on their own circuits, as will laundry rooms, so you might have success if you just route the lights around the apartment to various locations (i.e., plug one into the kitchen, one into the living room, one into the bathroom). That's probably being excessively overprotective, but it should make sure that you have no problems working with a small Arri kit.
 
If you have access to your breaker box, you will see how many and what size circuits you have...

If you look at an outlet and one of the slots is a "t" then it is rated as 20 amps (assuming a professional installed it correctly).

Code requires a separate circuit(from fridge, stove if electric) in the kitchen so an outlet on a wall above a counter should be its own circuit. Also true in the bathroom...code requires a dedicated circuit.

Sometimes you can tell when lights on are the same circuit by flicking on/off and watching the other light to see if there is a blink...

Technically you can run 1800 watts off a 15amp circuit and 2400 watts off a 20 amp circuit but for a margin of error...like Barry says...use 1 amp = 100 watts.

Also, outlets on either side of a shared wall are often the same circuit so avoid that when spreading out...

Perhaps you know this but make sure your stingers are rated for the draw...household stingers are generally not rated for over 15amps so if you were using a 2k that would warm that sucker up...although an arrikit won't have over a 1k in it, but if you cube tap a couple lights together then keep an eye on it. Also, if you are using dimmers make sure they are rated for the fixture you are dimming.

RJS
 
>Sometimes you can tell when lights on are the same circuit
>by flicking on/off and watching the other light to see if there is a blink...

Oooh, Good tip! Better than diggin out the fox and hound...
 
If a 15a plug could support around 1200w, does this mean I could safely plug in a 650 into one plug and another into another plug and so on without worrying about the aggregate of the total energy requirements of all of the lights?

Cool Lights said:
Normal, modern apartment buildings will typically have at least 15a plugs and breakers as will a house. That's pretty much a given based on building codes. (Unless you live in an area without building codes and they do exist!). With older construction all bets are off and you have to do a little more leg work to verify what's going on.

Normal, modern commercial construction like offices will have 20a plugs and breakers.

For your reference, a 15a plug/circuit should normally support up to around 1200w load without too much problem--but of course your mileage may vary based on all the variables involved including the quality of the wiring in the walls.
Click to expand...
 
Should have read all the posts before I asked my previous question.

Barry_Green said:
Tungsten lighting is extremely power-hungry. On a 15-amp circuit you could use maybe two 650w lights, as long as nothing else is powered on that circuit.

For shorthand, a 15-amp circuit should support 1500 watts. A 20-amp circuit should be able to support 2000 watts. There's some margin of error there, but it's a shorthand rule that should give you some ideas.

Frequently bathrooms or kitchens will be on their own circuits, as will laundry rooms, so you might have success if you just route the lights around the apartment to various locations (i.e., plug one into the kitchen, one into the living room, one into the bathroom). That's probably being excessively overprotective, but it should make sure that you have no problems working with a small Arri kit.
Click to expand...
 
monkeyking said:
Turn off the coffee pot. That and the toaster/microwave can ruin your day if on the same circuit.
Click to expand...

Does a coffee pot, toaster, microwave, and other similar devices draw much power if they are not being used?


Thanks so much everyone for taking the time to respond!!!!!!!!!
 
They draw no power to speak of, just make sure that craft services doesn't fire any of those up when the lights are on the same circuit.

Hair dryers and large CRT televisions too...
 
Mark-P said:
What type of damage is being caused if the lights go out?
Click to expand...

A breaker tripping is no big deal...just flip the breaker back on or change the fuse if that's the case...in the bathroom or other wet area a gfi outlet is probably used so don't forget to check that...a breaker tripping ruins your day if something else goes down...or a performance is interrupted.

If a stinger is overloaded it will get very warm and could melt...could cause a fire. I've seen the ends melt but have not seen a fire. Good SOP to glance at all connections/sometimes touch suspect stingers and make sure to keep a nose out for unknown smells (non-human)!

The bigger concern for overloading circuits is when you are in the midst of an area that you don't want to have a circuit go down...like an office full of pcs or a hospital, etc...although those places should have dedicated/protected circuits for their critical stuff...but don't count on it! I was shooting in a Target store in their data area and innocently plugged a 1k into a 20 amp rated circuit...circuit went down along with their computers which ran the checkout lanes...they freaked in a big way...my responsibility...but a 1k in a 20amp circuit should not go down....those computers should have been on a protected/iso circuit with battery backup if they were so important.


Appliances would draw negligable power if not being used...but better to unplug them lest someone forget and nuke a cup of coffee...

Not sure I understand this question: If a 15a plug could support around 1200w, does this mean I could safely plug in a 650 into one plug and another into another plug and so on without worrying about the aggregate of the total energy requirements of all of the lights?

1 circuit could consist of multiple outlets and sometimes practical lights(like cieling lights)...you could plug several lights into those multiple outlets as long as you are not exceeding 15a(or 20a)...ex: if your arri kit consists of a 1k, 2 -650 and a 300...and let's say you assume all your circuits are 15amps...then you could plug in the two 650s in one circuit (for example a bedroom) and you could plug in the 1k and 300 into another circuit(for example the kitchen). You needn't run separate power for each fixture...you could cube tap them into a single stinger...1k and 300 into cube tap into stinger running into kitchen....the two 650s into a cube tap running into whereever else.

If you are going to be working with lighting it would be good(if not required) to have a rudimentary understanding of electricity and even a little bit about how wiring is done...checkout a household wiring book (like from home depot). Then find a book like "The Set Lighting Technicians Handbook" by Harry Box (yes it is his name) might be a little advanced but there is tons of good info in there.

Good Luck!

RJS
 
Yeah, I guess we should have clarified that -- 1 circuit does not mean one outlet! There are almost always multiple outlets on each circuit. You may find that all the wall outlets downstairs are shared on one circuit, and all the wall outlets upstairs are shared on another circuit. Then the garage, bathroom, laundry room and kitchen may have their own circuits.
 
When shooting in a small room, using normal house power, I run power from the other side of the house for half of what I need and the other half from the room i am in. I have had problems before I started doing this so i just avoid it up front now. Avoid using "power strips" if you were leaning in that direction.
 
Nothing wrong with using power strips as long as you are working within the specs of the power strip and the circuit its plugged into...as a matter of fact I use a power strip when I want to simultaneously turn off a group of lights for an effect...as someone flipping a switch off/on leaving or entering a room.

Another thought: If you will be doing a lot of shooting in a location and have access (such as your own place) and you will be utilizing a lot of fixtures just map out the circuits...if you are on your own plug in a boom box with music playing and flip the breaker you think it is plugged into then label each outlet with its circuit. Obviously you do not want to be flipping breakers that something important is plugged into. Some locations you can request to talk to maintenance staff and they will mark the outlets/circuits for you...and if you are real lucky they will even drop you a distro box with all the power you need!

Another thought just to confuse matters more: just because you have 10 (or however many) - 15 amp rated circuits does not mean that you can use them all simultaneously...a small household breaker box may have 20 breakers in it maybe 15 - 15a circuits and 5 - 20 amp circuits...this would add up to 335 amps and a household generally has 160 amps coming into the house. If you plugged a 1k into every circuit in the house you may blow the fuse out on the pole, which i've seen...

I never did it but people still occasionally tie in to the breaker box...I avoided this mostly because I didn't want to die...also, technically I believe you need to be a licensed electrician...one other thought as it applies to electricity: if you do not know what you are doing it is probably best not to do it.

RJS
 
Just a quick note. This all applies if you in the US with 110v/15amp circuts. If your not, then you have to redo the math. For instance here in australia, we have 240v/10amp. So that means on one circut we can run a 2k, or technically a little more (2400w to be exact but you want some headroomas barry said so really only a blonde.) Im not sure about europe and the rest of the world, but if your somewhere else you have to redo all the math. Which is why its wise to know all the basics of voltage, current and so forth.
 
in Germany we have 230V and household circuits breakers are 16A.
Gives you a little more headroom, 3kW is not a problem, even 3.5kW is ok if you don't switch it on all at the same time.
 
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