my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Lamphouse wire size and type (Page 1)

This topic comprises 3 pages: 1  2  3

Author Topic: Lamphouse wire size and type Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 01-02-2010 11:06 AM                     So what is the right or best type of wire to use for the DC connections of a lamphouse? Also, what is the proper wire size? I know it depends on amperage and length. What is the best way to determine this?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-02-2010 11:38 AM                     Welding cable...can't beat it...it is high strand count for flexibility...available in most sizes in black or red. The longer the run, the higher the amperage, the larger the gauge. Without commenting further, Strong uses 4awg for 2500-Watts and smaller and 2awg for 150A and smaller...on runs less than 10-feet. We will often use 1/0 for larger lamps (4KW-7KW). Steve  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 01-02-2010 11:42 AM                     "Ask an electrician." Size of the cable should be determined by the maximum allowable voltage drop you are willing to tolerate, which should be primarily dictated by length of the run, but also has to do with what your rectifiers can support. Length (and current) dictates voltage drop, which dictates the wire gauge. Look this up in the NEC, or your favorite table. For short runs that flex, welding cable is expensive but nice. For long runs (unlikely in modern booths, but possible), THHN is cheap and reasonable. (Hmm, I see Steve posted while I was typing. Well, I'll post this anyway...) --jhawk  |  IP: Logged Tom Sauter Expert Film Handler Posts: 163 From: Buffalo, NY, USA Registered: Sep 2000 posted 01-02-2010 11:45 AM                        Once in a pinch where a loose lamphouse connection overheated and burned all the wiring, an auto parts store was able to supply me with battery cables of the correct guage and stranding. They even had nice shiny new terminals! Its important to note that insulation that is UV and high heat resistant is important inside a lamphouse, so read specifications carefully.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-02-2010 11:46 AM                     Welding cable is not that expensive for what it is. #4 is good for 100 amps continous. Note also that N.E.C. specifies that wire feeds for Arc Light or Xenon circuits should be the next larger size than one might ordinarily use for a given circuit. So be sure to use the next larger size wire for that feed so you pass inspection. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-02-2010 02:22 PM                     Yeah...I've never had welding cable be a cost issue. Many places will sell you cut-lengths so you only need buy what you need. THHN is a poor choice, I my opinion, as the connection to a typical lug in the lamphouse or rectifier is not likely to be optimal. Welding cable just plain works well. Steve  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 01-02-2010 02:27 PM                     Typical welding cable has a 60 degree C jacket. I usually dress that type cable at high temperature points with 3M #27 glass tape. Better is 90 degree C rated HOFR welding cable. Best is 150 degree C silicon/glass jacket cable or thermal / U.V. resistant cable such as Cobra X-Flex 150.  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 01-02-2010 02:34 PM                     The case where we used THHN was a 50' run from rectifiers to lamphouses. That's probably atypical. But THHN was substantially cheaper than welding/battery cable. Though looking at the pricing now, they are closer than I recall. --jhawk  |  IP: Logged Ian Parfrey Phenomenal Film Handler Posts: 1049 From: Imbil Australia 26 deg 27' 42.66" S 152 deg 42' 23.40" E Registered: Feb 2009 posted 01-02-2010 03:04 PM                     John. Do you know what kind of voltage drop you had over that 50' run?  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 01-02-2010 03:28 PM                     This was 4AWG and 2k bulbs, and I think the 4AWG was undersized. My notes (fragmentary, I might be misreading) suggest we saw about a 4V drop under load (way too much!). On the other hand, it (90C THHN 4AWG) was much better than what it replaced (60C TWG 6AWG). Why do you ask? I guess we can measure it easily enough. --jhawk  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-02-2010 04:01 PM                        For longer runs "code" diameters are not large enough. Poor lamp life can be attributed to voltage drop (only during ignition) across long lengths of cable. Inrush current at 4000 watts is easily over 1000 amps; for that reason, Strong has specified up to #000 for high wattage bulbs. This makes the case for having the rectifier nearby, like in a console. You will note that Christie uses wire on the smallish size. Part of their regulation is that very voltage drop. Louis  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 01-02-2010 04:22 PM                     Since I'm only dealing with 2K lamps and the runs are no longer than 5 or 6 feet, #4 welding cable sounds good.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-02-2010 04:42 PM                     Yeah...do a google search...you'll find suppliers that supply red and black by the foot.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-02-2010 06:54 PM                     Note though that welding cable is not 600 volt cable so it should be ennclosed in flex, conduit or what ever. If you need cable with 600 volt rating as a few local codes specify then locomotive cable is the only route you can go. It's identical to welding cable except for it's 600 volt rating. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-02-2010 10:40 PM                     actually welding cable must be in free air as its insulation is not rated for in flex we buy what is CSA rated entertainment cable now days for our dc leads  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1  2  3

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.