So, now that I have a bench power supply (0-+/-25V at 0-1A, 0-6V at 0-5A) on my bench, I need a set of test leads for it. Considering that I have had variable experiences with power supply test leads in the past, and that bench clutter is a major issue for me, I was planning on making my own up vs. buying premade leads.
Wire
For the wire, instead of using test lead/prod wire (whether PVC or silicone insulated), I was thinking of using UL AWM 2468 or equivalent "zip lead" that is more typically used for the output leads of DC wall adapters. This has the advantages of keeping the number of leads and the amount of bench clutter down, while having reasonable properties (80°C temperature rating) and availability. It's also available with pre-molded barrel plug ends, which is useful as it's difficult to homebrew proper strain relief for a barrel plug.
However, despite these upsides, I still have doubts as to whether this type of wire would be suitable under workbench-test-lead conditions; furthermore, the thickest I can get it in is 18AWG — is this thick enough for a set of bench supply test leads, or should I be using thicker wire yet?
Connectors
Other than the barrel plug ends, I am going to be terminating these with header pins (for direct connection to breadboards) and stackable banana plugs (both on the other end of leads that connect to breadboards or PCBs, and in the banana-to-banana case). This leads me to my other main line of inquiry: what is the best way to attach stackable banana plugs to test leads? I have my choices between:
- Solder-attach (where the wire is put through a hole in the contact piece, soldered, and then folded back into the housing when the housing is fitted)
- Setscrew-attach (where a clamping setscrew is used to "pin" the lead wire to the contact assembly in a back-wired arrangement), and
- Spring-clamp-attached (where a pushbutton-operated spring-clamp replaces the setscrew for holding the wire to the contact assembly).
Which one of these would yield the best reliability under bench conditions?
Best Answer
If it is NOT for (semi-)permanent setups, but it is for acutual "heavy-duty" bench work, I'd stay away from anything than silicone-rubber-insulated multi-stranded wires. If a hot soldering iron is around it is extremely easy to melt away a simple PVC insulation, and the fact that the positive and negative wires are kept so close together means a guarantee for nasty shorts if you are unlucky (especially if the power supply can deliver high current spikes).
Moreover, good silicone rubber insulation together with multi-strands makes your life better when handling wires on your bench: they don't stick to each other and to other wires (DMMS, scopes, etc.) and it is easier to move them around without dragging lots of things with them!
Moreover, these kind of wires are made to be moved all the time. Normal PVC insulation might not survive well the "hard life" of the bench top. You could end with an insulation with cracks and cuts that can fail you just in the worst possible moment.