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style="margin-bottom: 0">300' To The Gennie

Published : 4thj April 2007

>500amp generator, pulling about 350a and a 300' run to the set. What size camloc should we use?

>Thanks

>David Winters | DP | Los Angeles |


>David,

>What lamps are your running? And what is the distro beyond your first D-box drop? You should be okay with banded 5-wire. [I assume you are running three phase] the voltage drop over 300` is fairly negligible, I think it's like MAYBE 12 volts, if you are pulling max load on the cable, about 300a per leg.

>I'd suggest you run the genie a little hot, at about 124 v per leg should be more than fine. If your best ir worried (of if the gear owner is private) you could consider running 200' of 2/0 and the rest in 5 wire, but I don't see that as a problem.

>Jared Hoy
Gaffer || BBE || Cinematographer
Los Angeles, CA


>David Winters wrote :

class="style2">>>500amp generator, pulling about 350a and a 300' run to the set. What >>size camloc should we use?

>Assuming a 3 phase 4 wire 120/208 set up and assuming that by CamLoc you mean wire size, then 4/0 (Four ought) should be fine. Otherwise you will have a theoretical voltage drop of roughly 5.5 volts at the end of your 300' run -- assuming full 120/208VAC at the generator.

>Cable and connector condition will have some effect. Often the voltage can be boosted slightly at the generator.

>4/0 is generally rated at 310 amps for power transmission, but that's fairly conservative so the 350 amps is not a problem.

>To calculate voltage drop :

>Voltage drop = amps X feet X 18.7 (for single phase, for three phase use 21.6) divided by the cross section of the conductor in circular mills (C.M)

>4/0 has a cross section of 211600 C.M. You do the math.

>Brian Heller
IA 600 DP


>Brian Heller wrote :

class="style2">>>4/0 is generally rated at 310 amps for power transmission, but that's >>fairly conservative so the 350 amps is not a problem.

>I think he is talking about 350 total not per leg, more like 125 leg which is the high end for #2 banded.

>4/0 is not necessary. 2/0 would be fine esp if you might go over the350amps.

>John Roche, gaffer
NYC


>John Roche wrote:

class="style2">>>I think he is talking about 350 total not per leg, more like 125 leg >>which is the high end for #2 banded.

>I was never very good at mind reading, which is why I included the formula.

>However, my admittedly hasty calculations give a voltage drop of about 17 volts for #2 wire, and about half that or 8.5 for 2/0.

>Brian Heller
IA 600 DP


>Hi Brian, David and Jared, hope you're doing well.

class="style2">>>4/0 is generally rated at 310 amps for power transmission, but that's >>fairly conservative so the 350 amps is not a problem.

>I think 5-wire banded (#2 gauge) will be fine. 150+ amps per leg. 4/0 is rated at over 300 amps, but in a single-phase 4-wire system, you have two legs of it, so 600amps. In a three-phase 5-wire system, you have three legs of it, so over 900 amps.

>As to the question of camlock size, there are indeed two sizes of camlock : big and small.

>We generally use the larger, 400amp rated size, but there is a smaller size available. Maybe you have a vendor trying to use this type? I can't say I'm that familiar with it, and don't know for how much power it's rated. Google doesn't seem to be helping me this morning with this.

>Best,
Graham Futerfas
LA based DP, also former set lighting technician
www.GFuterfas.com


>Graham Futerfas wrote :

class="style2">>>I think 5-wire banded (#2 gauge) will be fine. 150+ amps per leg. 4/0 >>is rated at over 300 amps, but in a single-phase 4-wire system, you >>have two legs of it, so 600amps.

>I agree, but the voltage drop is still over 10% for a 125 amp per leg load for a 300' run using a balanced three phase 5 wire system, so if voltage is a concern....

class="style2">>>As to the question of camlock size, there are indeed two sizes of >>camlock : big and small. We generally use the larger, 400amp rated >>size, but there is a smaller size available

>The standard Cam-Lock connector for film work is the middle size or 4/0 size which is rated to 400 amps/600 volts. The largest is for 350-750MCM or 690 amps. The smallest is for # 8 to #4 wire and will handle 150 amps continuous.

>Try Googling: "Crouse-Hinds Cam-Lock".

>Brian Heller
IA 600 DP


>Thanks for all of the replies.

>I must make an effort to learn more about power distro, cable gauge, and voltage drop. On every job I'm always too busy lining up the first shot and getting the look underway. This is a 3 day job in Dec, old building downtown LA, third floor. Approx 100a per leg, three phase. Multiple, rock and roll strip lights (120w x 12 globes), Intelligent lights (Mac 250s and Prowash 250w), DMX controlled Kinos, and Tweeines. From the parking lot up to the 3rd floor main distro drop will be about 300', from there 25-75' to each head. Once we get a gaffer and bbe booked I won't have to deal with it, but for now I'm helping production with a budget and trying to get my complete wish list. The strip lights will be on the floor, everything else will be rigged overhead.

>Will we be ok with banded 5 wire or do I need to budget 2/0 for the 300' run?

>David Winters | DP | Los Angeles |


>David Winter writes :

class="style2">>>Will we be ok with banded 5 wire or do I need to budget 2/0 for the >>300' run?

>Personally I would run the 2/0 and not worry any more about it. Cable is relatively inexpensive. When I was a gaffer I always over-cabled because it avoids any potential overheating problems from a large load.

>Sometimes the load may not be as perfectly balanced as figured out to be on paper. This gives you a little head room for an unbalanced load, avoids potential overheating problems, and eliminates voltage drop which may affect any light with a ballast.

>That's my 2 cents.

>Jim Sofranko
NY/DP


>Here is a link to a voltage drop calculator;

>http://www.lexproducts.com/technical/calculator.htm

>And one example of entertainment feeder spec here :

>http://www.lexproducts.com/technical/specsFeederCable.htm

>If its new entertainment grade #2 you top out at 190amps per leg if its older welding type grade #2 more like 125 amps per leg.

>With entertainment #2 At 125 amps per leg with a 300ft run you end up w/ about 112v

>So can you boost voltage at genny?
Are you positive you will not exceed 350amps?
Are you positive its 300ft and not more?
Can you be sure to balance the legs closely?
What is ambient temp? Below 30C?

>If no to any above, for piece of mind go with 2/0. 2/0 will give you 115v at 300ft at 125 amps per leg w/o any voltage boost from genny.

>One other thing I forgot is the return on the neutral leg. Depending on what you are running, it COULD be necessary to have a heavier gauge neutral. (Esp if you run #2 hots -- you see this in theatrical set ups w/ dimmer racks and the like, they double the size of the neutral)

>My 2 or 3 cents.

>Best,

>John Roche, gaffer
http://www.libertylightinglimited.com/


>Jim Sofranko wrote :

class="style2">>>Personally I would run the 2/0 and not worry any more about it.

>That would be my call also.

>Too many things can come up/change at last minute and bite you in the ass.

>John Roche, gaffer


>I would plan on ordering maybe 100` in 2/0 and 300' in banded 5-wire and let your BBE decide what to make his juicers run. that is a good point about over gauzing the neutral if you're nervous about it.

>Jared Hoy
Los Angeles, CA
Gaffer || BBE || Cinematographer
818.795.3838


class="style2">>>Will we be ok with banded 5 wire or do I need to budget 2/0 for the >>300' run?

>David

>You need to think this out a little more.

>What's the lamp size in the strips... 500w each = 20a per leg.?

>How many are you using?

>Now how are you controlling your movers?
Are you using dimmers?

>100amps on a gennie gets you around 75amps full load per leg.

>Time for you to get that gaffer and programmer.

Later

>Tod Olivieri
LD/programmer
FT.Lauderdale, FL


>David,

>I would go with the banded. You can't exceed 500amps because of your gennie, and I think even the banded would handle that for a short period of time. 2/0 will take a lot longer to run and set up, and it doesn't sound like you're powering all that much. The strip lights are less than 2000watts, and the other lights all seem like less than 1Ks. If the voltage is low, just adjust it with one person at the gennie and one person at the end of the run with a multimeter and a walkie.

>Based on a 500amp gennie, I really think 2/0 is overkill. Banded is the practical solution.

>Graham Futerfas
LA based DP -- Local 600 and 728
www.GFuterfas.com