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Scotch-Lock Failure - Randy’s Electrical Corner

Posted in How To: Electrical on July 4, 2015
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I like a nice set of finely manicured nails as much as the next guy. Um, I mean on a girl. I’ve never had a manicure; my nails are a wreck. So are my cuticles. Wait, hold on—this is going the wrong way, and we are getting away from the point.

The point is, I think I’m getting old. I made a comment the other day about something bothering me about as much as someone scraping their nails on a chalkboard and the three people there were completely lost. When did chalkboards go out of style? Or when did people stop scraping their nails down them to get someone’s attention?

I’ve asked about 10-20 people about this since and no one knows what I’m talking about. The padded room, that is. Oh, no, I’m talking about Scotch-locks. Right, this is an electrical column. Scotch-locks bother me as much as nails on a chalkboard. I see them or someone mentions them, and I twitch just like someone would if you scraped your nails really hard on a chalkboard. But somehow that doesn’t mean anything anymore. When did that particular reference go out of style? Am I really getting that old?

Oh, right, back on topic here. Scotch-locks bother me because, by their very nature, they cut wires when you install them. On a Jeep, that means that you are making good and sure that you will have a failure of whatever electrical thing you hooked up. The vibrations will eventually let the connector cut all the way through the wire. I ran into an ’11 Wrangler Rubicon recently that had lights wired in with these things, and I think I passed out for a few seconds. Don’t use them. So, this column is dedicated to Scotch-locks (or whatever you call them), how they work, why they are horrible, and alternative methods of connecting wires besides these evil, evil things.

Here is how these nasty things install: You squeeze a piece of metal into the wire surrounded by a piece of plastic. The metal pierces both wires you are connecting. As a nice added bonus, it cuts both wires a little bit. Oh, and it cuts the insulation of the wires too. No, really it’s a great way to connect wires, especially in a Jeep where you guys are bouncing down trails 1,000 miles from nowhere for days on end. Here is how these nasty things install: You squeeze a piece of metal into the wire surrounded by a piece of plastic. The metal pierces both wires you are connecting. As a nice added bonus, it cuts both wires a little bit. Oh, and it cuts the insulation of the wires too. No, really it’s a great way to connect wires, especially in a Jeep where you guys are bouncing down trails 1,000 miles from nowhere for days on end.
Here’s what happens to a wire in a Jeep after being connected with one of these things for a while. Yep, it failed. Thankfully this was only an auxiliary light, but I’ve seen electric engine fans, fuel pumps, and other things wired in with these things. Guess what happens? Oh, and the other fun part of these things is that they aren’t even a little weather proof. So, even if they don’t cut through the wires totally, in basically anywhere but the desert, the wires will start to corrode the second you install one. Here’s what happens to a wire in a Jeep after being connected with one of these things for a while. Yep, it failed. Thankfully this was only an auxiliary light, but I’ve seen electric engine fans, fuel pumps, and other things wired in with these things. Guess what happens? Oh, and the other fun part of these things is that they aren’t even a little weather proof. So, even if they don’t cut through the wires totally, in basically anywhere but the desert, the wires will start to corrode the second you install one.
Look, I know it’s a pain in the butt, but if you are going to tap into a wire, this is the right way to do it. Don’t use a Scotch-lock. Use a quality wire stripper and cut the insulation—and only the insulation—about an inch back on the wire. See the cuts? Then use a utility knife to cut the inch of insulation away. Be careful to not cut the original wire with the either the knife or the strippers. Look, I know it’s a pain in the butt, but if you are going to tap into a wire, this is the right way to do it. Don’t use a Scotch-lock. Use a quality wire stripper and cut the insulation—and only the insulation—about an inch back on the wire. See the cuts? Then use a utility knife to cut the inch of insulation away. Be careful to not cut the original wire with the either the knife or the strippers.
After that, take out your trusty soldering iron I showed you guys how to use, like, 1,000 years ago. Wrap the new wire around the exposed section of old wire and solder it in. I usually wrap it with just electrical tape because I am cheap. However, some self-curing silicone tape, such as Rescue Tape (rescuetape.com) makes for a better and more weather tight seal. The problem is you can’t use marine heat shrink and if you cut the original wire, the connection is more likely to fail with the vibrations your Jeep sees. After that, take out your trusty soldering iron I showed you guys how to use, like, 1,000 years ago. Wrap the new wire around the exposed section of old wire and solder it in. I usually wrap it with just electrical tape because I am cheap. However, some self-curing silicone tape, such as Rescue Tape (rescuetape.com) makes for a better and more weather tight seal. The problem is you can’t use marine heat shrink and if you cut the original wire, the connection is more likely to fail with the vibrations your Jeep sees.

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