replace wire/what guage

[vinnytruck]

Good Afternoon guys, can anybody tell me what wire guage to purchase so I can rewire the "M". I know black, but looked around and nobody is talking guage size. I will buy a roll. Have 24v system thanks vinnytruck

[w30bob]

Hi Vinny,

The majority of the truck was wired in 14ga Prestolite wire. So far the only wiring I've found in 12ga is the jumper harness that feeds the circuit breakers under the dash. If you want to use the Prestolite I belive Saturn Surplus sells it in bulk, as do other surplus dealers. I'd suggest you ask when the wire was manufactured and only use fresh stuff if you're going that route. Personally I plan to use the latest and greatest automotive wiring when I re-do my harnesses, as that stuff is unbelieveably durable. I'm talking the cross linked polyethylene stuff that everyone sells these days. The only issue with the poly is that its rubber coating is thinner than on the Prestolite so the rubber sleeves on the Douglas connectors will be loose. I plan to fix that by using the 12ga poly, as it's OD is the same as 14ga Prestolite. Can't hurt to upsize when it comes to wiring.

How's that for a long convoluted answer to such a simple question?

regards,
bob

[jimmy_stikx]

Bob,

I was looking at the prestolite wire and converting the connections to the packard style where I can.

I need to do it because honestly, whoever did wiring on it before left it looking like a rat's nest and the lights barely work at all.

[w30bob]

Jimmy,

You're not alone brother......I think MOST M37's have rat's nests for wiring. It is amazing when you think about it just how f%$#ked up wiring can get. Scared the heck out of me.

bob

[vinnytruck]

Hi Guys, thanks for all the responces... Hows this stranded THHN #12_ this is used in electrical piping and a friend has alot, but not black. Whats you thoughts??????? vinnytruck

[w30bob]

Hi Vinny,

Well.....I didn't know much about THHN, so I looked it up. Gee this internet thingy is great.

Here's what it said;

THHN Wire stands for Thermoplastic High Heat-resistant Nylon coated. THHN can come in stranded or solid conductors depending on the size. It is either manufactured in copper or aluminum and covered in a PVC (polyvinyl chloride) insulation with a nylon jacket. THHN is UL listed with a rated 90 degrees Celsius in dry locations or 75 degrees Celsius in wet applications with a THWN rating. The vast majority of THHN building wire carries a dual rating on the cable marked THHN / THWN for both the wet and dry temperature rating. THHN building wire may also be used for wiring of machine tools, control circuits or on certain appliances.

THHN building wire has several main distinctions compared to other building wire products. THHN uses a thinner PVC insulation which is a key factor in terms of its electrical properties. This thinner insulation can often lead to a current leakage and even a breakdown during chemical or environmental exposure. The PVC insulation in THHN also creates a toxic smoke when burned therefore making it undesireable in certain applications.

THHN is not a very flexible product due to its nylon coating. This can often be a factor for many contractors or end users since there is usually a preference to use a product that saves energy and time during installation. However, THHN building wire has grown in popularity since it is a cost effective alternative compared to other types of building wire such as XHHW building wire. Despite some of its down falls, many users of THHN building wire have found this products to be sufficient for meeting their projects specifications.

I also looked up the ampacity for #12 stranded (copper I assume and not aluminum) and it's rated at 20 amps. I think most of the breakers in the M37 are 15amp....but there may be a 20amp breaker in there, for what I don't know....radios or a heater maybe. That might be cutting it a bit close.....but drop Majorhitt a PM....he's an electrician.

So reading what I found it sounds like THHN is made for use inside buildings, not so much out in the elements. The things that caught my eye are the lack of flexibility, possible current leakage, and low amp rating. But I don't know how that rates to the stock Prestolite wiring. Maybe someone can jump in here and help us out.

regards,
bob

[powerwagontim]

It would be a nightmare now and forever to use THHN in a vehicle. It is stranded, but the strands are MUCH larger, ie. not nearly as flexible.
Tim

[PoW]

That, and the bullet terminals won't fit 12Ga, unless you use all the larger belled ones with the larger wire hole.

#14 marine is a better choice. High strand count like the original.

http://www.waytekwire.com/item/MW14-0-1 ... RINE-WIRE/

One place to look, probably outlast you & the truck.

DG