Proper wire splicing, terminating, and pulling techniques
This is a 3 part tutorial, covering wire splicing, terminating, and pulling techniques. Most of us splice wire without giving it a second thought, however, nothing should be overlooked in a boat or marine environment. So we will look into some recommendations for splicing wire. Imagine then you have a couple of wires that you need to splice together. These could be a NMEA-0183 connection from a chartplotter to a VHF radio, needing a few feet more on a length of already installed wire, or any other scenario. Typically this discussion is limited to DC, AC, or low voltage signal wiring. RF Cabling will be discussed later. While crimping is the most common, other forms of splicing exist as well, including soldering, as well as using euro-style terminals. Finally, there are some devices such as the so-called "wire-nuts", commonly used in home electrical wiring, that do not belong on a boat.
In this example, we have a 4 wire connection, but only need to connect the Red and Yellow wires. The Blue and White wires are not simply unused spares. Of course, if we were connecting all 4 wires, everything should be self-explanitory. The bare end of a wire such as this is commonly called a "pigtail". We are assuming that the wire came from the manufacturer with the ends already stripped, so the first thing we need to do is to "comb" the wires we are connecting (which simply means to move the unused wires out of the way).
We plan on using crimp barrel terminals, so we'll layout the wires and terminals prior to crimping. Note that most crimp terminals are color coded; with RED used for 22AWG to 16AWG wire, BLUE used for 14AWG to 12AWG wire, and YELLOW used for 10AWG to 8AWG wire. Of course, terminals are available for other wire sizes, but this range of wire is probably what you will see on your boat (with the possible exception of battery cables). Note that all wires must be stranded, so we won't want to use any terminals designed for solid wire. Further, to meet boating industry standards, all terminals should be insulated (i.e. refrain from using bare terminals). Lastly, terminals are available with or without adhesive heat shrink, and their use depends on your application. I like to use the heat shrink insulated terminals for any area that is prone to getting wet, but due to their cost, I use standard insulated terminals for other areas.
Investment in a high quality crimp tool cannot be over-emphasized. Refrain from using those cheap multi-purpose crimp/wire sripping tools, as they do not provide a good crimp. I typically use two different crimp tools, both of which are of the ratcheting type, and are shown below. The tool to the left is a Thomas & Betts Stake-On tool that I found used for about $20. The tool to the right is a different style ratcheting tool that I paid about $20 for at Parts Express. Even though this tool was made in China, I have had good results with it. However, some tools are too cheap for a good crimp, and you can pay up to $150 or more for a new high-quality crimper, so keep a lookout on eBay for used high-quality tools.
Whatever tool you use, it should be a ratcheting type, as this provides a good crimp. Also, most crimpers will have 3 dies - for each of the three popular sized terminal shanks. The dies are usually color-coded Yellow, Blue, and Red to match the terminal colors. Before making the crimp, inspect the terminal and see how deep it is, then strip the wire so that the wire bottoms out in the terminal. Here again, a good wire-stripper is necessary, and the more you spend, the better the tool. Find a stripper that will not nick or damage the wire. This is especially important with stranded wire, as you can bust wire strands otherwise.
To make the crimp, you can often "hold" the terminal in the crimper's jaws with the first "racthet" position - which should hold the terminal, yet not deform it. Then simply insert the wire into the terminal, then squeeze the crimper until the last ratched position is reached. This will release the jaws so you can remove the terminal. Using the same process, crimp the other wire to the terminal. When finished, tug on the wires with a pretty good pull to make sure the crimped terminal is secure.
After you are satisfied the crimps are good, you next need to return some integrity to the cable as well as protect the unused wire ends. To do this, cut the end of each unused wire off - AT A DIFFERENT LENGTH FROM IT'S NEIGHBORS - so that there is no chance for any sliver of wire to short between each wire. If you do this, you can simply leave the ends of the wire bare.
Next, dress the wires on the cable so that they all lay down as best as you can. If your properly combed the pigtails in the first step, you should not have any crossed wires, as crossed wires will result in a pregnant-snake looking splice. However, if you did - don't worry about it, as it will probably not be an issue - unless you are feeding the cable through a hole in a bulkhead, and the spliced cable becomes too large to fit through the hole.
Lastly, tape the splice using electrical tape with a spiral motion. Note that all tapes are not equal; especially if the cable is subject to freezing weather outside. If that is the case, use a low-tempurature tape, such as 3M Super 33+ vinyl tape, which provides good performance to 0 Deg F, but is also water resistant. Avoid using cloth electrical tape as it is won't stand up to outdoor use. Of course, you could also use heat shrink, but I prefer tape, especially if I am feeding the cable through the boat. Also, if used outdoors, the tape must be resistant to UV (Ultra-Violet) damage from the sun. Not all tapes exhibit this property (although 3M 33+ tape does)..
Next we'll discuss soldering techniques. Click on Soldering Techniques below to continue.