Wire Ferrules

First, I am not building or making anything (except terminating wires) but rather showing the proper method for using wire ferrules. If you are using stranded wire in a project and have never used ferrules, you might be interested in this.

Wire ferrules, also called bootlace ferrules, are used to crimp together stranded wire terminations for use in bus bars, circuit breakers, ground lugs, screw terminals, etc. When simply stripping a stranded wire and inserting into terminal, you risk having 1 or more strands of wire sticking out, posing a shock hazard to people or worse, introducing a short in a circuit.

Enter the Wire Ferrule. I have used these extensively in my solar project here at the house as well as some electronics projects. Ferrules are normally tinned copper and are available as insulated, many colors if desired, uninsulated, and in various wire sizes. I buy mine in square millimeter (mm2) size since I am in Thailand, and they can be purchased in AWG wire size as well. Ferrules are used on single wires or two wires together.

Photo 1. The common ferrules used in a solar project are typically green, black, and red. The front row are double wire 6 mm2 (10 AWG) ferrules for the first three, next is a double wire 4 mm2 ferrules and a single wire 4 mm2 ferrule. Second row are single wire 6 mm2 ferrules, the back row is single wire 4 mm2 ferrules. The two white ferrules are to show the size variation available, those come from a ferrule kit I have that has various smaller wire gauge ferrules.

Ferrules, various sizes, but for this I will be showing ferrules used with 6 mm2 (10 AWG) wire.

Ferrule Crimper, I prefer the 4 jaw ratchet type. I have not used the crimper with the different sizes in the jaws. The 4 jaw type can crimp 0.25 to 6 mm2 size ferrules.

Non-contact Wire Stripper.

Cable Cutter, very handy for larger diameter wires and for trimming up excess wire from the end of the ferrule.

Wire to practice with, again, I am using 6 mm2 (10 AWG) ground wire as I was actually fabricating some ground wires for my panel rails.

I am using two 6 mm2 ground wires so I will be using a green two wire 6 mm2 ferrule.

Now when using a single wire with a single wire ferrule, once the wire is stripped, no over twisting of the strands, once the insulation comes off, simply twist to keep the strands in the same lay as they were in the insulation.

And for double wires, NO twisting the wires together first, then it will not fit in the ferrule.

For a single wire ferrule, basically you are going to strip the same length of the metal tube, and for double wire ferrules, strip off 2-3 mm more than the length of the tube. After you do this a couple of times, you will get the hang of it.

For a single wire, just gently twist the wire as you insert into the ferrule, ensuring no strands are sticking out from the insulation, goal is to insert all strands into the ferrule with the insulation stopping against the ferrule and the end of the wire flush with end of the ferrule. If the wire is not flush with the end of the ferrule, remove the ferrule and strip 1-2 mm of insulation and insert again. If there is some strands sticking out from the end of the ferrule, we will take care of those momentarily.

For a double wire ferrule, hold both wires together side by side, with the insulation at the same level, gently place a double ferrule over the exposed wires and gently twist and they will go right in. Goal is to have the wires completely inserted into the ferrule with the insulation at the ferrule and the wires flush with the end of the ferrule. If the wires are not at the end, remove the ferrule and strip a little more off of each wire and add the ferrule again, if there is wire strands sticking out, we will take care of that momentarily.

Insert the ferrule into the crimper right up to the insulation, squeeze and the ratchet will catch, continue squeezing until the ratchet stops then you can open and release the crimped ferrule. A proper crimper ratchets closed and only releases after the ferrule is completely crimped.

If there is any strands sticking out from the end of the ferrule, just use the cable cutter to trim them flush to the ferrule.

Photo 1. A double ferrule has two 6 mm2 wires inserted into it.

Photo 2. After crimping.

Photo 3. A single 6 mm2 wire with single ferrules on each end.

Some brands of solar cable have thicker insulation than the diameter of a regular insulated ferrule. There is two ways to solve this problem.

First, you can use a razor knife and just trim off some of the insulation, the trimmed part is the length of the insulation on the ferrule.

Second, you use a uninsulated ferrule, and this is quite easy. No need to buy uninsulated ferrules, just place a ferrule on a workbench, standing on its insulation, and tap the ferrule with a scrap of wood and the ferrule will come right out. Now just crimp as described above, you just will not have the colored insulation.