Lighting Question

[highmarcs]

I want to get a very basic three light lighting kit that puts out a total of 1250 watts.

I want to shoot in a very, very, old house. From maybe 1900. It did have it's fuse box replaced about five years ago for a breaker box, when they added central air to the residence.

Can I use a lightkit in such a place. Is that alot of wattage to draw. Will it blow something or burn the place down?

[Chewy]

welcome to the forum

since a hair dryer draws that much power or more you should be safe

of course 2 hair dryers on the same 15 amp circuit tend to trip the breaker

[highmarcs]

A hairdryer draws that much? Really?

I have used hairdryers on high in this house before and nothing bad happened.

But, should I maybe run exstensions and plug each light into a different room on a different circuit. Besides when I do any taping, of course the air, all the t.v.s, other lights,fans, dishwasher, and clothes washer will all be off?

Are AMPS pulled more important than wattage?

I'm worried because I had an electrician tell me once that he wouldn't install a combo lightswitch/a.c.plug in my bathroom because the old wiring of the house wouldn't be able to handle it. Was he giving me a line of bull to get a big rewire job out of me? Like I said, I've used a hairdryer on high in the neighboring bedroom before with no trouble. I had it on for a Loooooong time too, because I was drying a very fluffy dog with a dense undercoat after a bath. If I remember correctly, I think the lamps in the room may have dimmed ever so slightly in the room, but that was about it.

[drfsupercenter]

Hair driers use like 2KW, or 2000W.

Amps are what make the circuit breaker trip, but watts are nothing more than amps multiplied by volts, so those two will vary directly.

Having too many things on one circuit can be bad... but if a hair drier doesn't blow the fuse, a 1250W light set won't either.

[Chewy]

you wanted him to break code with your request, if you had paid him to run a new dedicated circuit then it would have been fine

a lot of older houses used 20 amp breakers on 12/2 wire

[ed klein]

If you are sure your total wattage is 1250 watts I would do the following.

1. If you have a fairly new circuit breaker box then look for a spare position to install a new 15 amp circuit breaker for the new lights.

2. Turn the main circuit breaker off coming into the circuit breaker box, then install the new 15 amp circut breaker using the hot black 14 awg lead.

3. The white return lead goes to the white section of the circuit breaker panel.

4. The green lead safety goes to the bottom of the circuit breaker panel where all the other green leads are located.

5. Use 14AWG romex wiring, (black, white, and green leads) to run your circuits. Also, called 2 wire with ground.

Watts is a product of volts times amps for DC circuits only but for simple AC circuits you can use that calculation to. Normal running current for 1250 watt load is approximately 10 amps.

DON'T PUT ANY MOTOR CIRCUITS ON YOU NEW LIGHTING CIRCUIT THEN DRAW 3 TIMES THE NORMAL RUNNING CURRENT ON START UP AND WILL TRIP YOU NEW 15 AMP CIRCUIT BREAKER.

[RFBurns]

In the engineering world, we use what is called "the safety margin" for determining maximum capacity on delivery systems (wireing, outlets, breakers etc).

This safety margin is usually a +/- 5 percent tolorance yielding a total of 10 percent across the value. The +/- 5 percent is used on light loads under 10 amps.

For higher loads and voltages the safety margin jumps up to +/- 10 percent and sometimes up to +/- 20 percent. This applies to 20+ amps and at the higher supply voltages of 220 or more, single or multi phase.

The basic rule of thumb is give your systems enough headroom for load surge at powerup or load sag, more commonly known as "inrush current". Any large wattage or amperage device such as studio/filming lights that average 1000 watts or more will produce at turn on a spike load on the voltage and delivery system (wireing/breakers), and only for a few milliseconds, but it is enough time of a spike load to trip breakers or possibly make connections along the wireing to break or spark or worse..get hot enough to break its connection possibly causing a fire.

Old homes from the early era, especially homes that when build did not have any electrical wireing, will have very light capacity wireing and outlets. These electrical systems are not safe with today's codes, which is why they are being replaced with more current up to date delivery systems.

Another thing to consider is this. Duty cycle. A hairdryer is not a continuous duty device, meaning it is not on for long periods of time. Chances are that your lights for filming will remain on alot longer than the use of a hairdryer. The continuous load will put more strain on the old wireing system and is a potential for disaster.

What I would do is get a roll of 240vac romex wire and connect to the main breaker box into a seperate little breaker box. Tie into one leg of the 240 mains and ground (giving 120vac) into the new little breaker box with its own breaker. A 20 amp breaker will handle 2 1000 watt studio lights just fine. Then run the rest of the romex to an outlet assembly for your lights. This way you are not using any of the old house internal wireing at all and provides you a safe way to power your lights for filming and taking power directly from the AC mains as it enters the primary breaker box, bypassing any and all of the house's old wireing and outlets.