Stinger / Extention cords for Lighting... Gauge/length/watts?

MadHMC150

MadHMC150

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Hi All,

I gathered some good info already but wanted to know exactly what stingers will work well with the lights I have been using.

After running about 2500watts through an old 100' extension cord (prob 14ga) - I melted the plug off... Thank god it got me through the shoot since I had no option at the time.


So- most of the time I am using a few Arrilight 650's, Tota 1000's and other misc lights from 600-1000 with or without dimmers. Oh and can't forget the Mole 2k.

Should each light have its own stinger? Will this new 12ga stinger replacement with a 3 plug splitter run 3 lights? What exactly is the recommendation for gauge to watts ratio that is not going to burn down the set?

-Thanks
 
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Let's figure out the amperage for a 1K instrument.
Using Ohm's Law, the current (amperes) is equal to the power (watts)
divided by the voltage, in other words, 1000/120 = 8.33.
However, most American grips use 100 volts to do the math,
because it makes the calculation easier, and also provides a safety factor.
So that 1K fixture pulls 1000watts/100volts = 10 amperes.

Now check out the Voltage Drop Calculators here:
http://www.lightshow.cc/explorer/Calculators/Power_/power_.html
We want to keep our voltage drop under 5%, both for safety and for color temperature.

Running the numbers, your 1K instrument on 100 feet of 18 gauge copper,
will have a voltage drop of 6 %. That's too much already. You were running
2500 watts, which is a drop of 15%!! That lost power becomes heat,
which is what melted your connector. It also meant your lights were
running much warmer than 3200°K.

You neglected to mention the rating of the fuse or circuit breaker.
They are typically 16 - 20 amps, so your 2K Mole needs its own breaker,
and if you're running the stinger 100 feet, the cable would have to be
at least 10 gauge.

Time to go to the hardware store...
 
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Thanks, just what I was looking for.

So my 12ga 50" can run up to 2500watts which includes the grip safety factor. It would have a voltage drop of less then 4.8, which is acceptable..

The breakers were beefy, not sure exactly but it was a sound stage made for it. I wasn't using the mole 2k either.
 
You should pick up several stingers. No matter what the breaker is rated for, I wouldn't run 2500w through a 12g stinger. All the pre made stingers I've ever seen, were rated for 15A and I've made a few stingers myself and all the ends I've ever found locally were all rated for 15A.
 
You want find any edison stinger that will handle a 2500 watt load. You will need to step up to bates connectors and a heavier cable.
 
MadHMC150 said:
Thanks, just what I was looking for.

So my 12ga 50" can run up to 2500watts which includes the grip safety factor. It would have a voltage drop of less then 4.8, which is acceptable..

The breakers were beefy, not sure exactly but it was a sound stage made for it. I wasn't using the mole 2k either.
Click to expand...

I hate to be "that" guy, but this thinking scares the hell out of me! Sure a perfect 12 gauge SO cable may be able to take that BUT your standard 15amp Edison connector is only rated for 15 amps. Hence the reason that you melted the connectors. The next thing that people fail to take into account is the resistance added by the connectors, I have seen many fail under much lower loads because the connector was not making a good connection. Even with a 20amp bates you shouldn't exceed 18 amps on the line. Then there is the whole factor of the breakers and what their rating is. Most standard panel breakers are only rated for 80% loading. If you use a true lighting distro or dimmer rack then those breakers are usually fully magnetic and rated for 100% load.

Here is something that may be a little more detailed than what is needed here but it is good information on breakers and derating cable.
http://www.etcconnect.com/img/whitepapers/AN101_100__Cont_Load_4pg.pdf
 
bclighting what do you mean most standard breakers are rated 80% loading. you mean my wall socket if it is 15amps type socket, that means it is really only capable of safely doing 80% of that which i imagine is somewhere around 12amps?
 
I'm not an EC (electrical contractor) so I can't really rattle off the true codes and NEC ratings. There are many factors at play when it comes to breakers. I believe one of the biggest is heat. If you had a panel loaded with 40-20amp breakers all continual loaded to near 20 amps you would have a big problem. I know that because I had to deal with a dimmer install that had that problem. Their solution there was to bump the breakers to 25 amps which can be done on 12 ga wire. The age of the breaker is the next thing. Older breakers tend to not hold as well but even more dangerous than that are the old ones that do not trip at all. Your wall socket will most likely work just fine up to the full 15 amps when you need it. If you were pulling that on it 24/7 and you had a panel full of breakers that had a good load then you may have issues.

Not to confuse even more but there are also breakers that are rated for high temps and ratings. You can expect the price of them to be double or triple standard breakers.

To break it down to the basics: Just because it says 20 amps doesn't mean that you should be loading it that high. Keep some headroom, it adds peace of mind. No one needs a breaker to trip in the middle of a shot ;)
 
Great info, thanks guys. Still leaves me to believe its not an exact science since there is so many variables... I am just going to check on cables a lot more often and use a good stinger for each big light (1k+). The other night, I ran about 2200watts through the 50' 12ga for a few hours and it was cool as can be.
 
bclighting said:
To break it down to the basics: Just because it says 20 amps doesn't mean that you should be loading it that high. Keep some headroom, it adds peace of mind. No one needs a breaker to trip in the middle of a shot ;)
Click to expand...

Absolutely, its all a bit different here in Australia being on 240 - but general rule of thumb is to allow 25% overhead.
 
Bates 20A on 14/3 would be appropriate for a 2k, not 12/3 SO on a 15 amp Edison - unless that were a Nema 5-20 type.
 
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