In The Shop: Ban Finger Twisting
May 08, 2011
Okay folks, I apologize if this devolves into a rant, but it's time to put an end to the practice of connecting electrical wires by twisting together the bare ends, then wrapping the splice with electrician's tape. I know, I know, it's quick, it's easy, it doesn't require special tools, connectors or splices, but...finger-twisting has the potential to cause SO many problems, many of them expensive.
Electronic systems on modern farm equipment often operate on as little as 4 volts. Finger-twisted connections are "loose" by nature and often get "looser" due to vibration or tension on wiring harnesses. Finger-twisted connections generally are "protected" by only a couple wraps of electrician's tape, which is prone to allow moisture in but not let it out. I can't count the number of times I've unwrapped electrician's tape to find rotted green wires that were the cause of electrical problems I was diagnosing.
I'm not a great fan of traditional crimp-on butt connectors. They give decent electrical contact, but are open to the weather at the rear of their insulated covers, allowing moisture access to the bared ends of the wires. When I have to splice electrical wires I often use crimp-on butt connectors with heat-shrink insulation. The crimps do a good job of connecting wires, and the heat shrink insulation both seals out moisture AND "glues" the splice together to add strength.
Even better are crimp-on, heat-shrink butt connectors with built-in solder. After crimping the connector, when heat is applied to shrink the insulation, it also melts a drop of solder built into the butt connector. The final splice is crimped, soldered and heat shrunk--a mechanic's dream splice.
Last week I ran across a third option: a screw-together butt connector. Instead of crimping the connector, the wires are held in place by two threaded caps that tighten the wires against a central conducting post. I'm told the threads hold better than a traditional crimp because the wires get caught/compressed in the threads for a super-secure splice.
The down-side of all my preferred methods for splicing wires is that they add cost. Heat-shrink butt connectors range from a 50 cents to a dollar or more each. Those nifty heat shrink/crimp/soldered splices range from $3 to $5 each. That can get expensive if you're repairing a 32-wire harness for a planter seed monitor.
Having said all that...yes, I confess I have twisted and taped wires together as part of emergency repairs. But I promise that as soon as the machine limped to the end of the row or into the shop, my twisted repairs were replaced by some form of good, solid weather-proof splice.