tom_kat
way upstate new york/lake george area
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Joined: 02/28/2005
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I'm one of those when it comes to 12 volt wiring that use a larger gauge then necessary ,having worked in trucking fleets for 20 years and seeing the small burnt up wiring because it was over loaded and to small or at the minimum size for what the circuit was for I choose to go larger and not have to worry about it again.its not that expensive to do it right the first time then to have to go back later and repair it again or maybe start a fire or melt up a whole bunch of wireing because one wire was to small.
1985 Class A Holiday Rambler Imperial 33 +1979 Class C Holiday Rambler Statesman 1000 = 24 ft
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javaseuf
Southern Cal
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Joined: 03/30/2005
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Larry & Linda wrote:Actually copper in this sense is cheap.
It is much more cost effective to have only one size wire to deal with than have to worry about running three sizes and not have a wire large enough when something needs to be hooked up. Same thing applies to having a wire too short
Larry
Exactally! When I was building Class A's, we used a pre-made wiring harness that was built on a 40' table in the factory. The jig for the harnesses was designed to be used for all of the models and lengths of coaches we built. To take the time to change-out wire to different gauges would be time consuming in labor so the extra cost for the next gauge of wire is a wash as far as money.
Also, most manufactures that pre-wire their harnesses, make one harness for a mutitude of models so one model may have more of a load and require 12 gauge and another may only be a 23' coach with only two lights on the same wire and yes, could use 14 gauge but too expensive and time consuming to shut down an assembly line to change out reels of wire.
Steve
2007 Springdale 291RKL
2003 F150 King Ranch
2001 Dodge Van w/Wheelchair Ramp
1991 Palomino Mustang PUP
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"Politically Incorrect And Proud Of It" 
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Dennis Bham
Alabama
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Joined: 03/13/2008
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The load that a wire is supplying is not the only concern as to what size to use for that run. It is just one piece of information used in choosing the appropriate size wire and fuse or breaker for the task. Wire size is determined by the fuse or breaker size feeding it. Fuse or breaker size is selected according to the total load it supplies.
For example, if a single fuse or breaker (say 15A) is used to feed multiple loads, then all the wires used for each separate piece of that total load downstream from the fuse or breaker must be sized to safely operate the fuse/breaker in the event of a fault without overheating the wire. If you used a very small gauge wire for one 1 AMP/12 watt load on that common circuit fused at 15A, the wire could become overheated and be a fire hazard by a fault at that small load location.
Dennis
'08 Chevy 2500HD Duramax 4x4, Crew Cab, Std Bed e/w 18K Superglide
'08 Cougar 292RKS, e/w 16" Sendel wheels & BFG Commercial TA tires
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res08hao
La Mirada, CA
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Joined: 07/15/2002
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I am going to make a blanket statement: the rv industry as a whole is the least skilled and poorest assembled product made anywhere on earth. There are few if any legal requirements, the skill of the workers are minimal, the management mostly does not care about the product. Of course there are exceptions, but as a general statement it is true.
It is also probably true that no two rv units are built the same because they are mostly eye-balled. The wiring I see behind the walls of my Coachmen look like a high-school shop project. Heck, be grateful they used copper instead of coat hangers or piano wire.
over the hill and enjoying the view
diesel pickup and 5th wheel trailer.
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snownyet
Western NY
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Joined: 07/11/2005
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Im thinking about scrapping out the excess copper in our rig to pay for fuel? LOL
2007 Montana Mountaineer 307RKD
2006 Chevrolet 2500 4x4 crew Duramax/allison
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SpoiledRotten
Central Mississippi
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Joined: 06/14/2004
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I wired my new barn last month and I threw away about 8 inches of unused copper wire. Please don't tell anyone.
Just the 3 of us...SpoiledRotten, TotallyRotten, and ALittleRotten
2000 F-250 Lariat, CC
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2005 33RL2 New Vision - AKA "SpoiledRotten"
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tom_kat
way upstate new york/lake george area
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shame on you for throwing it out,i keep it around its good for something sometime when you might need a jumper wire.
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travelnutz
West Michigan - On the Lakeshore
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Joined: 04/09/2006
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When dealing with 12 Volt DC, there's a real obvious need for using a very heavy gauge copper wire. People who deal with the awesome amperage coming out of a vehicle's alternator/battery know the difference!!! Also, the current loss associated with too small a wire size and/or the resulting fire from wires getting hundreds of degrees in temperature quickly due to the inherent resistance is very real. 12 Volt DC item's use requires approx 10 times the amperage required for 120 volt AC. 10 times 12 equals 120! 20 times that of 240 volt AC which is merely 2 - 120 volt circuits. DON'T CHEAT or cheap out!!! Overkill in wire gauge is not the hurt bump. Undersize wire gauge is! As to the extra length? Extra length/size is a real blessing not a scourge in homes, boats, and RV's etc. 1/2" short or exact length is not only frustrating, it's insane!!! Both conditions cause a lot of rubbing situations which compromise the wire's insulation and expose the bare wire. Weight is not crucial as in an aircraft. A manufacturer is not going to lower your cost of an RV just because they had shortened the wire length in their units. Thanks for PLENTY of extra length!
I have always wired my vehicle alternators/batteries output to the RV with #2 or #4 welder wire. Very fine and flexible heavy current carrying wire that's fused at each end with an 80 amp slow blow marine fuse. Not overkill but rather a very wise move! Ever notice your battery isolator under your vehicle hood is usually 100 amp or more? That's why it's of that size. Very simple common sense to this engineer!
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davelinde
Freehold, New Jersey
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Joined: 11/02/2003
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SpoiledRotten wrote:I wired my new barn last month and I threw away about 8 inches of unused copper wire. Please don't tell anyone.
Years ago after my uncle sold his electrical contracting business (and opened a campground of all things) he would pick up occasional contract work to help with expenses. During the summer I worked as his helper. Sometimes we were asked to quote the trim-out of something another contractor had roughed or we were asked to come finish a DIY started project.
More than once we ran across roughed out jobs with little to no slack in the boxes. My uncle would not even quote them.
Dave Lindemulder
Tammy, Mark & Kirsten
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jwcgc29
Wirtz, Virginia
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Joined: 10/04/2007
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Well...I certainly touched off a firestorm with my question and reply...need to be more careful in the future. I appreciate all the constructive input regarding the issue I raised and thank those respondents for not taking issue with the specifics of the verbiage I included in my OP or reply. For a bunch of folks that love to talk about relaxing, some members sure can get testy about the nuances in the delivery of any given message. I agree...RELAX....even if you dont like exactly how I state my case, please.....RELAX.
08 Carriage Cameo F34CK3
07 GMC Sierra 2500 HD 6.6 Duramax
00 Chevrolet Tahoe (retired T/V)
55 Beautiful, brunette RV loving Wife
06 Cavalier King Charles Spaniel "Roxy"
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