Electrical Wire Identification

For wire 1, google says "For 150 amps in THWN wire size is 1/0"

I cannot find wire 2. Perhaps compare it to wire 1, assuming it actually is 1/0. You can consult a wire table for that.

I would think all you'd need is a simple ruler to measure the diameter.

Are the markings printed on the wire as if from the wire manufacturer? Or is he talking about printed labels that were possibly installed by the coach manufacturer? I only ask because a 1/0 wire is a big wire which I find hard to believe is in a factory built RV.

OP: Please post make and model of your dad's coach

The wire markings idetify the wire's FUNCTION not the size but the purpose.

Beyond that I can not help.. For BIG I"m tlaking battery size big. a ruler might help
For smaller an adjustable wrench (The one that made crescent famous)

Then measure the gap in the jaws or take it (Tape over the adjuster) to the store with you.

NOTE if you are trying to add to or replace a 18 ga wire and all you have is 16 or 14. NO PROBLEM. the other way around PROBLEM You can always "Go big"

Image next to a fingernail?

As said..always go bigger on any manufacturer’s wire size you are replacing.

OP here, to make a short story long...

Dad's coach is a 07 or 08 Fleetwood Bounder Diesel.

He recently had the 12v JC Refrigeration compressor unit installed and has had several problems with it. I've been helping him troubleshoot the problems.

The latest problem could possibly be a result of excessive voltage drop in the 12v supply to the JC unit. The JC unit is supplied with a connector that plugs directly into the 12v supply wires to the original Norcold unit after the Norcold is unplugged. They also state that the 12v supply wires should be minimum 10 gage. I have doubts that the original factory wiring to the Norcold was 10 gage, thus the question about the markings.

I checked my wiring diagrams for my rig. They use a different coding.
Factory refer is more likely around 16 gauge.

wa8yxm wrote:
For smaller an adjustable wrench (The one that made crescent famous)

I always thought the rolls made crescent famous.

Seems like the wrong approach to me. Send him to the store and buy an cheap digital voltmeter. Measure the voltage at the refer with the comperssor running, no shore power and battery partially discharged. If it meets mfg specs then wiring is OK. Next repeat but measure at the battery terminals to make sure batteries are OK. Better yet have the batteries load tested. What did he find?

Otherwise measure the distance for new wires and use a wiring calculator to find the wire ga needed for the new wires. And go directly from the refer to the battery with a fuse unless there is some really heavy wire nearby that can be used.