View Full Version : General Wire Info - Mostly

Jimz Bird
07-17-2011, 05:35 PM
This is kind of an extension of another thread that I didn't want to get to far off topic so I thought it best to start a new one.

Like most of us, I have a real concern for the safe operation of our Classics. Wiring, Brakes and Reliability are some top issues.

Here is a site with lots of good stuff. It is mostly an EFI site but worth a look around at the tech stuff and products.

Here is a handy chart on Wire Gauge Sizes to use.


Also "How To Solder Like a Pro"


Battery Cable/Mega Fuse Assembly Solder


The bottom photo on that page shows the Mega Fuse wire completed. This is even more heavy duty than Dave mentioned and may be more than some need but it can't hurt to be extreme with some of this stuff.

In my case, my wiring is even older than most of the Birds here so I will opt for overboard.:D

Consider High Power Headlights, A/C, Electric Fuel pump, Auxiliary electric cooling fan. Some or ALL of those will be a real strain on the system. Of Course Relays are a must here also.

Side note on the Ford 3G Alternator - They are up to 130 Amp on such as Taurus and some others. There is also a large case and small case. The large has better ventilation and cools better. New after market ones go even higher amps. (That Heavy Duty cable is looking better all the time)

07-17-2011, 10:31 PM
Thanks - taught me something to make it easier.

07-18-2011, 04:49 AM
Good thread, Jim.

I would like to comment on each of your suggested sites:

1. Wire ampacity is determined by three factors; length, the cross section of copper wire and the type of insulation. Voltage and Watts mean nothing. Current creates heat.

Insulation performs two tasks, it determines the wire's voltage limit and the rate at which the wire sheds heat. These ratings are always printed on the wire. I use (minimum) 60C stranded copper wire that is gas and oil resistant.

We commonly use automotive wire, MTW, or THHN. They are all covered in the National Electrical Code, and those tables should be followed for real safety.

There is more... Automotive loads are DC, which 'never lets go'. 60-cycle house current is derated .707 times DC current. in real terms, 10-amps of DC equals 7.07-amps of AC (or RMS). This means your car wire needs to be larger than AC applications. Duty Cycle plays a big role for intermittent loads, like horns, starter motors, or flashers because the wire cools down between loads. Never skimp on alternator, headlight, or tail light wire sizes.

2 & 3. Don't solder. None of the OEM's do (and neither do utility companies) for good reasons. Use quality, plated, copper lugs (like in the picture) or splicing sleeves and crimp. How often do you need this service? Rarely. Any electrician will be more than happy to crimp a few connections for you for free OR, you can use a hammer. The idea is to squeeze the conductors tightly together to keep resistance at a minimum. Solder spreads the strands and keeps them far apart, (and it wicks up the wire). When serious current arrives, the solder will melt first and the spliced conductors may fall apart. Mechanical lugs work better than solder connections.

The picture shows 'Welding Wire' which has hundreds of very fine strands. This is the ultimate starter motor and engine ground wire. Welding wire tends to spread out when stripped. Some electricians use copper foil to keep all the strands together before inserting in the lug. Crimping makes it all one solid piece. - Dave

Jimz Bird
07-18-2011, 11:05 AM
This crimp vs solder seems to be quite a topic:


Proper Tools and Proper Technique appears to be part of the issue. Particularly with the thick cables. The tools are very expensive to do those large crimps properly. These are not your average hand crimper.


Perhaps best to consider having a battery shop or a nautical Marine shop do it for you or rent a proper tool.

Either way - BE SURE to put the In-Line fuse in.

07-18-2011, 10:27 PM
Jim, do you have any Electrical Contractors in your area? They ALL have huge crimp tools as part of their trade.

If you show up with a connector and wire, and tell them it's for your classic car, I guarantee you a few electricians will offer to crimp them for free. Otherwise, Harbor Freight has a hydraulic crimp tool (size 0 thru #14) for fifty bucks:
http://www.harborfreight.com/media/catalog/product/cache/1/thumbnail/370x370/9df78eab33525d08d6e5fb8d27136e95/i/m/image_1701.jpgAfter using it for your job, you can sell it for about the same money.

The solder/no-solder posts don't say what size wires they are working with. Most of our wires are small (#14 and smaller). Something is seriously wrong when someone can't squeeze enough pressure on hand-held crimpers, to properly crimp a #14 connector. I use Sta-Kon WT111M pliers. They are 9-1/2" long and look like this:
http://lh4.googleusercontent.com/public/RLvmmYElmwG2vxIIRd5SxtoadPU4R1_skcsLbRyGntGAMqJoCU W7KqiTFQrlOsM9aO9buhJ1r3fRuMQAUkGtD8fdW8gdTYLoEskQ muwLMRezXhxb5Ri7JIssx4XH00wMLBwnw5I_iFc6TQWhkdjivT 6LKYw_3JxMywdUNotice the leverage on these crimpers. Sta-Kon also makes lugs (connectors). All their stuff is top drawer.

Each connection should be pulled ****-hard. If wires come out, do it over. This applies to wire nuts, too. A loose connection creates heat from arcing, then carbon sets-up. Electrical failures most always occur at a connection, rarely in the middle of the wire. - Dave

Edit: I ran across this handy hammer-crimp tool for $16. It crimps wires from #8 thru 4-0:
http://ecx.images-amazon.com/images/I/31BpdZXLqLL._SL500_AA300_.jpgHere's the link:

Jimz Bird
07-19-2011, 09:38 AM
Ahhh, good reminder. My neighbor down the street is a retired Master Electrician, He still has tons of stuff in his garage. No doubt he or one of his buds has what I will need.

Thanks AGAIN!!