Does anyone know the exact name of the type of wire HD uses for its turn signals and taillights or where they source it from? I believe it's 18 gauge wire but what I'm asking is, is it THHN,THWN,THW or something else? All the 18 gauge stranded wire that I find at my local automotive stores has a much thicker insulator, that seems to be much softer than the factory wire that HD uses. The insulator around HD wires looks thinner and also seems harder. I contacted the dealership and they said they don't sell the wire. They also couldn't give me an answer to what they use in their factories.

Also, does hd use solid or stranded wire? I almost want to say I thought they used solid wire.

 

The wire gauge for those lights is probably 18. The type is typically referred to as general purpose or "primary" wire. Automotive wire is normally stranded. The gauge and insulation is determined by application but any quality automotive wire from a good source will be more than adequate. Do not use household wire and I would not use cheap automotive parts store wire except in an emergency.

If you can get it, aircraft rated wire is more expensive, but it is also far superior to automotive wire.

Here is a decent overview... http://www.wiringdepot.com/blog/Unde...utomotive-Wire

 

Most of the wire I have found is 20AWG. It is written on the insulation. You should hopefully have enough wire showing past the conduit sleeving to see it.

 

automotive wire is a cross-link polymer thermoplastic insulation and is heat and oil resistant. as far as mil thickness, depends upon voltage and amperage and insulation type as you mentioned. automotive copper will be of a softer grade as you called it as i do not think many houses take in vibration unless on a fault line. as mr. skinman suggested, primary wire from an auto outlet will do. just a suggestion, i use 16ga wire especially where the system has both gauges, easier.
TWP is thin wall insulation lead free 105*c
TXL is a thin wall insulation used in commercial trucking
SXL is a thick wall
GXL is in between

 

THW stranded

 

Cheap wire, like Harbor Freight is made from soy. Mice love it.