Difference between commercial and automotive wiring?

[farm boy00]

" I'm not worried too badly about flexability because this is bent hard in electrical boxes all the time and used in flexable tubing for line sets to rooftop units. "
That's not the type flexibility automotive wire require's. The ability to bend,straighten,bend,straighten,bend repeatedly without breaking insulation or conductor is flex I'm referring to. Repeatedly bend a THHN and automotive wire of same guage and THHN will break long before automotive. 10k viberations can equal 1 hundred sharp back and forth bends when it come's to work hardening and fracturing. This is turning into a debate,your question has been answered.

Thanks for the explanation.

 

[jaxs]

Thanks for the explanation.

You are welcome and don't overlook to include fuse(s) in the project. It suck's to have a short start a fire when least expected. :hissyfit:

 

[Birdhunter1]

So if THHN wire is bad to use why would you recommend something like thermostat wire? It is a solid wire that is easy to break which almost everyone says is bad to use.

That is a good question, it depends on where you run the wire and how you secure it. I typically secure it where it has flex and can move a little bit, i don't strap it to things that move, it is typically short runs and if passing through a firewall or box I use a grommet, and this will really make heads spin.. I use wire nuts often, but only in places dry like in the cab or in a box.

Call me crazy, say its foolish, say it won't last, but I had that Ranger for 10 1/2 years and I've done the same on a tractor I've had for 12 years and the only wire I have ever had to repair was if it got caught on something and literally ripped off.

 

[wagne223]

I thought this forum was for asking questions and trying to figure out answers and gaining knowledge but I guess I must be wrong on that.

That is exactly what the forum is for.

It seemed to me you were discounting the answers and information that was given and intended to do the project with the house wire anyway.

If I misunderstood your responses and my assessment is incorrect then I apologize.

 

[chim]

So if THHN wire is bad to use why would you recommend something like thermostat wire? It is a solid wire that is easy to break which almost everyone says is bad to use.

Maybe some posters don't realize THHN is available in either solid or stranded conductors? THHN is an insulation type, and does not designate stranded or solid conductor. MOST is marked "THHN/THWN", and I don't recall the last time I didn't see that dual designation. Most people in the trade use the name "THHN" alone, regardless of the marking (just as they call all NMC "Romex" and all facial tissues are "Kleenex").

The "W" means it is moisture resistant. Each individual strand in THHN is a little larger than those in the wire used for extension cords. However, wiring on a piece of equipment doesn't require the flexibility of an extension cord. It has a decent rating for heat (167F wet, 194F dry) and is gasoline and oil resistant. I avoid contact between the wiring and hot engine parts. The dry temperature rating applies to THHN, THWN and THHN/THWN. The wet temperature rating applies to THHN/THWN and THWN.

I've used different stranded conductor wires for tractor and misc. vehicle wiring for years and never had a problem. For heavier loads I've used THHN, trailer wire (flat 2 and flat 4) or whatever was handy. I have several LED blinkers that I wired with tinned stranded multi conductor cable that was left over from a sound or fire alarm system installation. One run gave power plus synchro and pattern change.

 

[Howling]

Wire has two parts: Conductor and insulation.

Conductor:
Typically copper. Other materials are used for specialty wires.

The conductor can be a single strand or multiple strands grouped together. Trade offs on cost and flexibility. Single strand or solid wire is easier to make cheaper. Most house and building wiring is solid, once in place doesn't need to be flexed. Wire with more and finer strands is more flexible. Battery and welding cables tended to be fine stranded wires. Typical wire used for appliances, equipment and vehicles are a medium stranding.

The size (or gauge) is measurement of the amount of copper in the strand. This size determines the how much current the wire can safety carry. Solid or stranded wires or the same gauge have basically the same amount of copper and same current rating. The current rating for a specific wire gauge comes from a variety of codes and standards based on use: building (residential, commercial), industrial equipment, appliances, vehicles, power distribution, etc.

Insulation
The insulation is the stuff around the conductor that keeps the current flowing in the wire and not to places you don't want it.

The type code (THHN, etc) defines the insulation material on the wire. Some types (THHN, MTW, GPT) are single conductor wires. Other types (NMC, SOOW) are multi-conductor cables (multiple wires grouped together).

The insulation type will define where it can be used (per the code) and wire properties.
- Wet or dry locations.
- Resistance to solvents and greases.
- Exposed or protected/ encased.
- Abrasion resistance.
- Thickness and flexibility.
- Maximum voltage the wire can be used for.
- Temperature rating.

THHN is used in a lot of building wiring and is commonly available.

There are a multiple wire types used in automotive wiring including GXL, SXL, GPT, SGX, etc.

I have done industrial equipment and control system design for 30 years and have specified and used a lot of wire.

 

[Dave M7040]

I will get to my point in a round about way.

Corroding steel brake lines are a problem on older vehicles driven in corrosive environments such as where road salt is used.

I took part in a Government study assessing the merits of copper alloy brake lines. The copper products turned out not to have the required durability from a phenomenon called work hardening.

The copper became brittle from movement, pressure pulses and vibration and would crack.

Copper wire behaves the same way. Fine strands tolerate the hardening as each strand undergoes less flexing than a single solid wire.

Best wire is marine grade tinned copper wire sold on Amazon. Each strand is completely coated in tin. Oxygen in the air we breath will defuse right through plastic wire insulation and slowly start corroding each strand. The tin coating prevents this from happening.

This link is to one of many different sizes and styles of tinned wire.

Amazon.com: 16 Ga (True American Wire Gauge) Tinned Oxygen Free Copper OFC Duplex 16/2 dual conductor AWG AC Marine Boat Wire with Type 3 Stranding: Industrial & Scientific

Dave M7040