Welding Cable - Any Downsides when used for Starter Motor???

[Jammer]

Originally Posted by Wotname

Cable was purchased yesterday. The insulation is fairly impressive and complies with The Australian standards quoted upthread. The outer appears to be PVC and the inner may well be.

I think you will find that the inner layer is polyethylene, possibly crosslinked, possibly not.


Ordinarily when they use all PVC they do it in one layer.

[Reefmagnet]

Originally Posted by Jammer

I think you will find that the inner layer is polyethylene, possibly crosslinked, possibly not.


Ordinarily when they use all PVC they do it in one layer.

PVC also melts. Not really suitable for a good quality welding lead!

[Jammer]

Originally Posted by a64pilot

[...] as far as shorting and catching fire, surely you fuse at the battery don’t you?

Large fuses don't provide effective protection against shorts.

"Shorts" are never zero resistance. With, say, a 10 amp fuse, this doesn't matter much, because either the fuse will blow, or there will be some fairly modest amount of heat dissipated from the short -- under 120 watts, because that's the most the fuse will allow. 120 watts is around the upper end of what is widely considered an amount of power that doesn't pose significant fire danger.

For example, the UL standards for appliances and electronics become considerably more stringent where the available fault power exceeds certain power thresholds -- I can't remember what they are exactly and there are different ones -- but they're around 60 and 125 watts or so. Above these levels the rules become more stringent for fireproof materials, distance between conductors, and so on. UL standards don't apply to boats but the safety principle is the same.

A starter motor lead that is fused at, say, 200 amps, can easily short out against a resistive object (for example, a steel bracket) that will conduct enough current -- maybe 100 amps for example -- to become dangerously hot without blowing the fuse. 100 amps is 1200 watts at 12v and that's enough to turn a steel object orange hot.

Therefore, while fusing the starter motor lead is a best practice, and one that can potentially prevent a fire, it is not by itself a sufficient level of protection to overcome the hazard posed by deterioration of insulation.

[Wotname]

Originally Posted by Jammer

I think you will find that the inner layer is polyethylene, possibly crosslinked, possibly not.


Ordinarily when they use all PVC they do it in one layer.

Originally Posted by Reefmagnet

PVC also melts. Not really suitable for a good quality welding lead!

I'm not entirely clear from the literature I have found so far but it seems like both layers are V90TH PVC (to AS3808) however they feel different.

The outer sheath is stamped 90C and other sources suggest 75C continuous but can withstand 105C for 500 hours per annum.

Needless to say, the engine room does not approach these temperatures nor does the duty cycle of starting allow for internal temperatures to get anywhere near these numbers.

[Wotname]

Originally Posted by Compass790

OMG I'm never going on that boat if I ever make it to Tassie!

Originally Posted by Reefmagnet

If thar crazy enuff to use welding cable they'll prolly have soldered connections too!!!


Deathtrap!

Originally Posted by Jim Cate

Unless you make it quickly the boat will likely have been consumed by righteous flames and consigned to the pit... so hurry on down!

I'm already calling the firies in a kinda preemptive strike. Gotta protect my pal Wottie...

Jim

Thanks for the laughs guys .

Now tell me, should I solder then crimp or crimp first and then solder - asking for a friend

[Wotname]

Originally Posted by Jammer

I think you will find that the inner layer is polyethylene, possibly crosslinked, possibly not.


Ordinarily when they use all PVC they do it in one layer.

The outer is stiffer and the inner "more rubbery".

Is there a simple DIY test for PVC and PE?

I will be keen to see how both layers respond to the diesel immersion experiment!

[Wotname]

As for Locomotive Cable, forget it, this is Tasmania where boat ownership is very high and locomotive ownership almost non existent. If I can't find suitable marine cable, there ain't going to be loco cable in the shops!

[donradcliffe]

I have also pulled welding cable out of a boat which had turned to dust. I think the guys who have had good experience must have been in fresh water. I was able to source tinned cable in Malaysia by ordering from west marine.

[Dsanduril]

Originally Posted by Wotname

I'm not entirely clear from the literature I have found so far but it seems like both layers are V90TH PVC (to AS3808) however they feel different.

The outer sheath is stamped 90C and other sources suggest 75C continuous but can withstand 105C for 500 hours per annum.

Needless to say, the engine room does not approach these temperatures nor does the duty cycle of starting allow for internal temperatures to get anywhere near these numbers.

For what it's worth (absolutely zero in Tas where it simply isn't applicable) UL 83 specifically mentions two (or three) layers of the same insulation to facilitate applying colored sheaths over a wire made with a single insulation color:

PVC insulation that is applied in up to 3 integral layers of differing colors (same compound) to facilitate color changeovers is to be treated as a single layer.

Got to believe that was put in the standard by the manufacturers to reflect how they actually make wire, because the whole rest of the standard says it has to be one layer, and then there's that one little nugget that says "three layers is one layer".

[Wotname]

Originally Posted by Wotname

Thanks for the laughs guys .

Now tell me, should I solder then crimp or crimp first and then solder - asking for a friend

OK, I have worked it out, it is best to apply crimping pressure while the solder is between the solidus and liquidus temperatures. This should ensure a good quality COLD joint!!!



And for those readers who have less perfect reading comprehension and can't follow a thread conversation - this a JOKE.

[Wotname]

Originally Posted by Dsanduril

.............
Got to believe that was put in the standard by the manufacturers to reflect how they actually make wire, because the whole rest of the standard says it has to be one layer, and then there's that one little nugget that says "three layers is one layer".

That is classic - thanks for finding and posting it.

Marketing / Sales manager - 'our cable has three layers of insulation"

Technical Compliance manager - 'our cable uses the three into one insulation construction method'.

[Mickeyrouse]

Aside from insulation and tinning, it my understanding that welding cable has a smaller wire count per a given diameter, thus is slightly less flexible. Once installed, it’s not going to be asked to make any more twists and turns. But is going to vibrate every time the engine runs, and bump every time the boat comes off a wave.
I have been able to source marine-grade cable for a tolerable premium over welding cable. When I re-wired our boat, I used about 120 ft of 1/0. Seems like it was about $2/ft more- well worth it in peace of mind. I think to do otherwise is yet one more opportunity for false economy. And for what it’s worth, Nigel Calder does not speak favorably of substituting marine-grade with welding cable.

[Lineguy]

Originally Posted by Hartleyg

There are big differences in the insulation used on welding wire - neoprene (and similar like "Carolprene", etc.)) are fine in the engine room, but EPDM is not. Unfortunately, EPDM is VERY common nowadays - if the wire comes in any color besides black, it's probably EPDM.

The problem with EPDM is its susceptibility to deterioration in the presence of oil, diesel fuel, etc.


Otherwise, just make sure your joints are properly sealed (adhesive-lined heat shrink, etc.) and welding wire works fine. My preference with welding wire is to crimp, solder then heatshrink (belt & suspenders approach!).



Hartley
S/V Atsa

I worked for an electrical utility for several years. We had some issues with copper neutral/ground connections in underground systems with corrosive, wet acidic environments. We went to welding cable, de-ox like Penetrox or similar, compression connections, self amalgamating tape, then vinyl tape or shrink tubing where applicable. Connections are still holding up over 15+ years.

[sailingharry]

Originally Posted by Dsanduril

Where, show us the law.

I stand corrected. Thanks. And that's not said tongue in cheek -- I'm always striving to learn, and the older I get the more I realize half of what I "learned" isn't always right (or remembered right....).


And before I posted this, I followed your links, I googled, I pulled up the current CFR, and, well, "learned."

[Cadence]

Originally Posted by sailingharry

I stand corrected. Thanks. And that's not said tongue in cheek -- I'm always striving to learn, and the older I get the more I realize half of what I "learned" isn't always right (or remembered right....).


And before I posted this, I followed your links, I googled, I pulled up the current CFR, and, well, "learned."

Being old's a bitch. But some of what you have learned maybe more valid that what some young Turks have to say. Turks being figurative.