Quote:
Originally Posted by ratdude747
My "2 strands" rule was for wires with a larger number of strands. Like 10 or more. Also note that the copper strands do connect internally (inside the wire), so the justification was that it's only missing for a short part, not the whole wire.
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So, the current carrying ability of the wire is specifically related to the cross sectional area of the wire, measured in circular mils. The strands are bare copper and do connect internally to each other but reducing circular mils at any point reduces the entire wire to the smaller gauge and therefor higher resistance.
I showed several teams over the weekend the method I use for stripping large gauge wire without damaging the wire. Using a sharp knife or box cutters, push the blade onto the insulation while the wire is laying flat on a table. Then roll the wire. This will allow the blade to travel through the insulation without cutting any strands. Do not move the blade, let the rolling action move it around the wire. When you have rolled all the way around the wire, then bend the wire at the cut and you should see copper. Continue to bend all around the wire. The insulation may be pulled off at this point with your fingers. If the insulation is really tight, take the blade and place it almost parallel to the wire and skim some of the insulation that you want to remove. Think like you are filleting a fish. As you remove the thicker part of the insulation, it will be easy to remove with your fingers. This method also does not disturb the lay of the strands, making it easier to insert in a terminal.
BTW, if you are using screw terminals like these...
https://www.grainger.com/product/BLA...onnector-3LT05
You must insert enough wire so that the copper is visible for at least 1/8" on the opposite side of the contact from where the wire enters. When you tighten the screw, the end of the wire showing will spread out to help assist with wire retention. If you do not do this, when you tighten the screw, it will simply push the wire out of the terminal and that leads to failure. I really prefer these types...
https://www.grainger.com/product/THO...pression-6MFT9 You can crimp them in a vise if you do not have the right crimper. To do this, insert the wire into the terminal. Then place the wire and terminal in the corner of the jaws at a 45 degrees for only half of the terminal. Tighten the vise until you can't any more. Remove the terminal and rotate 180 degress and crimp the other side. When done you should have a nice "X" pattern on the terminal when complete. Then give it a real tug test to be sure it is tight. We follow up with solder at this point.