Wiring - THHN??

[steved]

Its not Cummins... yet. Getting ready to rewire the M37, the old wire is laying bare on the frame in several places and I really don't want barbecued M37 at some point.



I have sort of decided on stranded THHN wire to work with, since it is high temp, for wet locations, and has the extra nylon sheath. Other than its stiff (making it a little more miserable to work with), I think it will work the best for the wiring on this truck. Being an older military truck, most of the wiring is exposed and there's not much to it really... lights, charging, and ignition is about it.



What does everyone else use for wire?? Any pros/cons to using THHN?

 

[tkerrigan]

Just make sure that there are lots of strands of copper. MTW or automotive wire is very soft, easy to bend, and is vibration resistant because of the number of strands and soft covering.

 

[steved]

Its not extremely fine stranded, the number 19 sticks with me. The THHN is also rated MTW if memory serves me?? I know its not as flexible as wire you find in the automotive section, but its a whole lot tougher (insulation).



I've used it in automotive applications before, wiring accessories and what not, with good results... I currently have most everything in my 04 hooked up with THHN, like the CB and other low-draw items.

 

[LMcCary]

I have rewired a lot of cars, trucks and tractors with THHN. That being said, if it is exposed to sunlight, you must tape or cover it. Actually the most flexible wire is SIS (if my memory serves me) which is very flexible, coated with either tin or silver alloy, but more expensive. It is used in most high end machine tool switch panels and flexible switch controls.

The most important item in the wiring harness is the connecters. Use high quality, heat shrink connecters with a mastic seal that melts to seal the wire. The best connectors is the Deutsch weather seal or AMP with the gold plated pin and socket like Caterpillar uses on their engines.

Next best thing, and very important is to fasten the wire harness down so it does hang by its own weight.

LMcCary

 

[CKelley1]

i agree , go with cabling used to wire trailer lights and brakes . you can get it at napa or car quest, if there is a surplus store near you ,look for so cable in the electrical

 

[Alphacowboy]

Steve, what ever wire you end up using, make sure its fully protected by some type of wire loom. Wires not in a loom are just asking for trouble.

 

[steved]

Steve, what ever wire you end up using, make sure its fully protected by some type of wire loom. Wires not in a loom are just asking for trouble.

I'll probably wrap it with friction tape (or fabric tape) to keep it *looking* the period-specific part...

 

[hcole]

As an electrician for almost 40 years and using all kinds of insulated wires I would say that thhn wire is one of the BEST kinds of wire to wire an automobile. It is oil and gas resistant and only the outer nylon covering is subject to cracking IF left in sunlight continually. Regular automotive wire insulation will also crack if left in sunlight. The wire will be exposed in this case. I have used this thhn wire a lot in cars and trucks over the years with excellent results.

 

[Dieselnut59]

THHN is good enough to use to power a fluorescent, metal halide or high pressure sodium light ballast and you should have no problem with it in a vehicle where it is not constantly flexing. Protect it from UV. I have noticed in light fixtures, where the light is exposed to it, the insulation does deteriorate. Use loom or tape, as you mentioned, in areas exposed to light. Heat should not be a problem. Ballasts get HOT, often so hot you cannot touch them. I believe THHN is rated for 120C.

 

[AKAMAC]

Period specific would be more like THWN or MTW as they are not jacketed and are rated at 105ºC.

 

[steved]

Period specific would be more like THWN or MTW as they are not jacketed and are rated at 105ºC.

Hardly... rubber-coated fabric (rubber-coated cotton more specifically)...

 

[CKelley1]

that is why i sugested so. the thhn is not flexable enough for what he is doing he needs more strands than thhn has. the trailer brake wire from napa or car quest comes in many gauges and grades and is used on tractor-trailers acros the usa, canada and mexico

 

[steved]

that is why i sugested so. the thhn is not flexable enough for what he is doing he needs more strands than thhn has. the trailer brake wire from napa or car quest comes in many gauges and grades and is used on tractor-trailers acros the usa, canada and mexico

The runs are simple, and mostly straight... nothing requiring a super flexible wire...



My main concern is temperature, in the engine compartment...