Posted 20 August 2008 - 02:04 AM
gelling the lights....can you even put a sheet of cto infront of a source this big with out it being in danger of melting? how would I go about doing this?
Stands, I often see condors or other cherry pickers used to get lights up higher....how high would I be able to get on stands? I dont need to get above 10 or 15ft. what kind of crew is generally needed to handle rigging up and operating 12ks...I'm having a key grip come on board with more experience then I have had, but would like to gather as much info as I can.
power, what power do sources this big run off of 480? I have never delt with anything above 240, but I do have a gaffer coming in with a good deal of experience as well.
Posted 20 August 2008 - 04:06 AM
However, if you are working with an inexperienced crew, or an understaffed crew, then I could see why you would need to get involved.
Fist thing, what country are you shooting in? Please let us know because the voltage is different depending on the country. I live in Los Angeles so I will answer your questions about power as they relate to the US. If you are in Europe or any other country that uses 240 as standard voltage, let us know so someone on here can answer for you.
In the US, your 1.2K, 2.5K, and 4K will run off of 120V. 1.2K Uses a stinger, 2.5K and 4K use a 60Amp Bates cable. 6Ks are sometimes 120 Volts, but usually 240V (for single phase, 208V for 3 phase). The 12K will run off of 240V. You should have at least 2 people to mount the 12K on a stand, 3 is better. These use 240V 100Amp Bates cable and draw power from 2 legs. Make sure your crew knows how to work with these lights. Never stand in front of them when they are coming on.
On the bigger lights, I would not recommend gelling the lights directly. Put the gel on a 4x4 frame so you can give the gel some distance from the light. If you are using narrow lenses, you will probably need to put a 4x4 frame of heatshield in front of the light, which would be behind the gel. If you are using a 12K Par, I would use the heatshield even on the wider lenses if you have it, Don't use any of these lights without a lens or you will melt the gel almost immediately.
Crank Stands like the crank-o-vator are pretty good and can go pretty high. I like the American Road Runner stand for the big lights sometimes. American Grip's website says the Roadrunner 220 has a maximum height of 11'3." Make sure you have the stand safetied if you go at full height. Don't forget to get enough ladders so your electricians can operate them. And make sure they are tall enough so they are not standing on the top 2 steps (Dangerous and illegal).
Obviously if you need to go really high and have the budget and crew with the experience, then you would want to use something like a condor.
Best of luck
Posted 20 August 2008 - 07:13 PM
couple follow up questions.
what do you mean by
"for single phase, 208V for 3 phase"
I don't have any experience with or have heard the term "phases" before.
"These use 240V 100Amp Bates cable and draw power from 2 legs"
so does this just mean its running off 2 separate outlets or sources to draw power or?
thanks for any more information on this!
Posted 21 August 2008 - 03:48 AM
Another question I have for you, Are you using a generator or mains power such as from a stage?
Here is my answers to your questions:
What do you mean by "for single phase, 208V for 3 phase"?
Let me clarify the wording. I think my use of parentheses was misleading, I meant to say you have 240 Volts (V) when using a single phase system and you have 208V when you are working with a 3 phase system.
I will attempt to explain phases, but I'll try to keep it simple.
There are two main ways to configure an AC (alternating current) power source (such as a generator). The 2 ways are single phase and 3 phase. Some generators are one or the other or both (can be changed with a switch, but power must be off when switching). If a power source is single phase, there are four separate lines coming out of the source. One line is the ground, the next is the neutral, and the remaining 2 are your hot legs which are your "phases." The connectors for these lines on the generator and your cable are color coded. Green is your ground, white is your neutral, red is a hot leg and blue is a hot leg. You run the matching cables from there to your distribution boxes. The power coming from the generator is 240V, but the neutral splits the voltage between the two hot legs making them each pull half which is of course 120V. So, the voltage between the red and neutral is 120V and the voltage between the blue and neutral is 120V. The voltage between the red and blue without the neutral is 240V. On a 120V Distro box, each outlet will have the ground, neutral, and one of the hot legs. If you are using a 240V light such as a 12K, you will need a 240V outlet (whether it is available on the box or made with a snakebite using the other side of a passthrough box. The latter method is not nearly as safe because you have no breaker protection, so I would recommend getting a box that has some 240V outlets.) This is one outlet, but it has no neutral. It just has the ground and your 2 hot legs. The term single phase can be a bit confusing since there are 2 hot legs.
In a three phase system. You have your ground, your neutral, and three hot legs. The color coding is the same with the addition of the 3rd hot leg being black. In this system 208V comes out of the generator. The neutral splits the voltage. The voltage between the neutral and each hot leg is still 120V, but the voltage between each hot legs (Red and Blue, Red and Black, Blue and Black) is 208V. If you have a box with 208V outlets each outlet will be one of these combinations: Red and Blue, Red and Black, Blue and Black. 12Ks also run off of 208V. The ballasts and handle the difference in voltage and take care of it. This is not the case with tungsten lights. A 20K tungsten light has several different types of globes that can go in the unit. They have 208V globes, 220V Globes, 240V globes. Don't use a 208V globe with single phase because the 240V will overvolt possibly making the globe explode. IF you use a 240V globe with three phase (208V from the power), you will get weaker output and reduced color temperature.
IF you want to learn this stuff, pick up a copy of Set Lighting Technicians Handbook by Harry C. Box. This book explains it better than I ever could. Then get as much practice as you can.
It sounds like you are fairly new at dealing with power distribution. Be very careful and do not start plugging things in without checking with someone who knows what they are doing. If the Gaffer is experienced with this stuff and knows how to do it safely, let he/she be in charge of this. If the gaffer is the only one on set with this type of experience, only let this person be in charge. No one should do anything electrical without talking to the Gaffer first (normally this distribution stuff would be handled by the best boy electric) It is important to learn this stuff, but learn to do it right and safe because if you are shooting this thing, you may not have time to double check that you are doing everything safely. I don't mean to scare you but make sure everyone on your electrical crew has a healthy respect for electricity (because improperly hooking things up can be harmful if not fatal).
You said the crew is inexperienced. This is understandable since they are not being paid, but using larger lights like this, especially raised high up in the air, you really should have some crew who knows how to safely work with this stuff. It is going to be very difficult for the gaffer and key grip to work effectively and safely with an inexperienced crew. This also increases the likelihood of equipment breaking.
What is the reason for the production not paying for the crew. Is this a student film? If not, you should explain to production that they really should pay for a more experienced crew. One thing I would recommend is to have all of the electrics at least read the electricity and distribution chapters of the Harry Box book (I swear, I don't work for the publisher). Then have them go to the rental house and ask if they could show them how to hook up a generator and do basic cable runs. If you are a student in Los Angeles, send me an email with your name and I can give you some resources for places that teach this stuff for free.
Best of luck
Posted 22 August 2008 - 01:18 AM