Welding Cable temp rating.

[akschu]

Reading through a few threads about starter and alternator wiring I see a lot of people recommending welding cable because it is cheaper and more flexible. Fair enough, that makes sense, but when I search amazon or some other outfit for the cable I notice that nearly all cable has a temp rating of 105c which is 221f. The ETFE insulation on the standard M22759/16 milspec stuff is 150c or 302f.

Over here @DanH suggests that under cowl temps can exceed the temp rating of the welding cable which could cause problems after hot restart or in flight with the alternator.

What are people doing to mitigate this risk? Firesleeve? I'm tempted to just pay the money and deal with the stiffness and install aircraft cable just to be safe, but figured I'd post in case I'm missing something.

Thanks!

 

[Carl Froehlich]

I run any wire or engine control cable that is under the engine in fire sleeve. If nothing else, it adds an abrasion barrier.

Years ago I was skeptical of using welding cable. As a test I took a piece of #2 welding cable and a piece of #2 Tefzel cable and put a torch to them. The welding cable smoked but did not hold a flame. The Tefzel melted. Since then I used #2, #4 and #6 welding cable in all my projects.

And no, I did not measure the temperatures during this torch test.

Side note - the welding cable is much more resitant to abrasion than the Tefzel. I do recommend verifying the welding cable you use is US made.

Carl

 

[akschu]

I run any wire or engine control cable that is under the engine in fire sleeve. If nothing else, it adds an abrasion barrier.

Years ago I was skeptical of using welding cable. As a test I took a piece of #2 welding cable and a piece of #2 Tefzel cable and put a torch to them. The welding cable smoked but did not hold a flame. The Tefzel melted. Since then I used #2, #4 and #6 welding cable in all my projects.

And no, I did not measure the temperatures during this torch test.

Side note - the welding cable is much more resitant to abrasion than the Tefzel. I do recommend verifying the welding cable you use is US made.

Carl

Appreciate the reply,

Seems like #2 is for the starter and #6 for the alternator, what are you using #4 for?

 

[Carl Froehlich]

Appreciate the reply,

Seems like #2 is for the starter and #6 for the alternator, what are you using #4 for?

I have a dual battery install (both PC-625s). The #4 is used to connect the two batteries to separate master solenoids. The combined output of the two masters feeds the #2 for the starter. A black #2 is the engine ground cable - grounded on the starter ground lug.

Carl

 

[DanH]

Like Carl, I've been flying welding cable (#2) for a long time. My lower cowl air temperature runs warmer than most, and the cable has never shown any sign of distress.

Like real estate, the most important thing is location, location, location. Run it too close to a hot pipe, and all bets are off.

BTW, the 228F in the referenced thread was temperature taken at the cowl exit, thus it included all the heat added by many feet of hot exhaust pipe. A cable run well inboard of the downpipes, along the sump flange, isn't going to be that warm.

All that said, I don't know anything about Chinese cable from Amazon.

 

[akschu]

Like Carl, I've been flying welding cable (#2) for a long time. My lower cowl air temperature runs warmer than most, and the cable has never shown any sign of distress.

Like real estate, the most important thing is location, location, location. Run it too close to a hot pipe, and all bets are off.

BTW, the 228F in the referenced thread was temperature taken at the cowl exit, thus it included all the heat added by many feet of hot exhaust pipe. A cable run well inboard of the downpipes, along the sump flange, isn't going to be that warm.

All that said, I don't know anything about Chinese cable from Amazon.

Are you also protecting it with fire sleeve?

 

[DanH]

Are you also protecting it with fire sleeve?

Nope.

 

[johnbright]

This is what I have in my notes:

• Wires 8 awg and larger can be welding cable for much greater flexibility versus M22759/16 Tefzel insulated hookup wire.
  • Insulation choices vary but B&C is a trusted source and sells EPDM insulated Flex-A-Prene (they call it Super-Flex) which is rated to 105C (221F). B&C offers only 4 awg. (The B&C website says it's Neoprene insulated but that is incorrect AFAIK, Flex-A-Prene is EPDM.)
  • I found awg 8 through 4/0 EPDM insulated welding cable on eBay from AC/DC Wire And Supply cut to length in one foot increments. What I received circa 2023 is Flex-A-Prene brand.
  • Bob Nuckolls says any brand that's EPDM insulated is good.
  • Neoprene insulated welding cable is also sold and is rated 150F (66C), seems like a bad idea.

 

[Freemasm]

An option if you go this route:

Welding Cable

WindyNation welding battery cable is a high-quality pure copper flexible cable manufactured in the USA! Sold in 4/0, 2/0, 1/0, 2, 4, 6, and 8 Gauge lengths ranging from 5 to 400 Feet, and black/red insulation. Bundle and save! Purchase welding battery cable with 10 pieces of cable lugs and 3...

www.windynation.com

This product could be ordered through Home Depot in the past but with free two day shipping, it probably isn’t needed.