Builders' wire

[Californio]

Hey folks,

I just installed a piece of 8AWG stranded builder's wire from the alternator to the + battery terminal to cure a low charging-voltage problem. Easy to do--just get 12 feet of the wire, put it in a piece of 3/8" polyvinyl tubing for extra protection, solder some good-quality copper eye connectors on (I had to use a torch as the soldering iron wouldn't heat wire that big), and connect at both ends.

Result: before 12.5 volts, now 14.5 volts at the battery.

Question I have, though, is this: is it ok to use builder's wire in an automotive situation? What's the difference? If it's not as heat resistant for engine compartment use, why not put an additional piece of tubing around it, as in fuel line?

Sure is cheap and it definitely carries the current.

??

[syncrodoka]

I dunno what builder's wire is?
I do know that automotive wire is more pliable to resist breakage from the vibrations transmitted while driving.

[buildyourown]

I'm afraid he might be talking about Romex?
If so, that is a horrible ghetto repair. Step up and spend the $10 on a real wire.

[TroySmith80]

Maybe he means single-strand wire? If so, yeah, vibration will likely get it eventually. You want something very soft and flexy for automotive applications.
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1984 Westfalia Wolfsburg - 2.5L Subaru - Sold - Preparing to move to the dark side (4x4 Ford van)

[PDXWesty]

Stranded copper wire used for building (THHN) doesn't stand up well to the heat and vibration in an automotive application. The copper strands are too big and rigid and are prone to crack. Auto or marine wire has many more strands and is more flexible. That's why they don't use building wire. Also, the wire insualtion holds up better to solvents and higher temperature and are less flammable on marine and automotive wire.
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89 Westy 2.1 Auto

[greenbus pilot]

I have a #6 welding cable from my alternator to the battery. Many fine strands in welding cable, and I got it free from work(after crimping on the appropriate lugs). Welding cable is THE way to wire a car.
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Sent from a white van down the street.

[simd0ggie]

In addition to stranded wire being more flexible, it also helps reduce electrical noise. Welding cable is fine, especially for areas with more vibration, but any stranded wire will do. Solid wire and romex are a no-no. MTW has a more flexible insulation and finer stranding, and it generally the type you'll find at Autozone and Radio Shack. THHN is stiffer & thicker stranded, but much more abrasion resistant, and is what you'll find at home depot.

Adding shrink tube will not make it any more heat resistant, it will only help with abrasion.
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-Matt
'85 Westfalia w/EJ25, '14 Tiguan R-Line 4 Motion

"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.”

[Californio]

What I used was stranded 8AWG from the hardware store. Cheap, but it sounds like there's a reason.

I've never seen 8AWG in the local auto parts places--why I used the builders' wire. To my mind the 10 and 12AWG automotive wires just don't carry enough current for a 12 foot run. Looks like time to search marine supply places online...anybody have a good source?

True, Romex would have that ghetto look...especially if you run it outside...

[simd0ggie]

Just go to the local electrical distributor and ask for 8AWG MTW wire.
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-Matt
'85 Westfalia w/EJ25, '14 Tiguan R-Line 4 Motion

"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.”

[PDXWesty]

I got mine here. Super fast shipping and pretty low prices for marine grade wire. He'll even make a custom cable and put ends on it if you like or provide them with the wire. Check out the site.

http://gregsmarinewiresupply.com/

You can get 6 ga marine battery cable for $0.99/ft
8 ga for $0.67/ft
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89 Westy 2.1 Auto

[Californio]

That's the kind of place I was looking for. All I could find online was 100' rolls of automotive wire, costing $100 or so. Thanks for the link.

[W1K1]

Go to your local auto battery store, ours makes cables any length/gauge with the ends crimped. And it was cheaper than the stiff cheap cables from Canadian Tire.
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http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[syncrodoka]

West Marine stores carry some heavy guage wire in bulk that is sold by the foot.

[PDXWesty]

[thummmper]

walters whlsl electrical supply or whatever supply stocks multistrand for auto/machinery.
the reason you don't want single strand wire is because electricity travels over the surface of metal, not through it. the jacketing is specialized for the intended use as well. like these guys said, the heat and vibration play into it.
Next time you drive past a power substation, look at the ridgid jumpers they use on the jungle gyms---hollow thickwall copper tubing for all those amps.

[syncrodoka]

[fatboypaul]

When I rewired my boat I came across a wire supply company that was excellent, this is their address.
http://genuinedealz.com/
Way cheaper than West Marine, fast free shipping, and they never messed up an order.
I'm also losing voltage between the alternator (14.4v) and the battery(13.6v). I'm a little confused as to why.

[Californio]

13.6 V isn't bad. That's about normal voltage drop for 12' of 10AWG wire. Mine was less than 12.5. Adding the 8AWG wire brings it up to past 14.

[PDXWesty]

[Perales]

VC has this cable for 12 bucks which they put together. If you want longer, they might be able to accommodate you.


http://www.van-cafe.com/home/van/page_780_235/alternator_cable_upgrade.html
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-- 1987 Westfalia automatic (Captain Vino)