I would strongly suggest an inline fuse on the positive side of the power supply. I'm doing this from memory so anyone feel free to jump in and correct me, but I think I'm pretty close on my estimates. It's not surprising the 22-24 gage wire melted first. It would only be able to take maybe 5 amps max of load depending on the number of cores before heating up, and a jammed wiper motor would be attempting to pull way more than that.I'm building a simple animatronic using a single wiper motor connected to a speed controller (similar to this one fright props sells). It's hooked to a 12v 5amp power supply, and being controlled through a relay. I'm not using park, just driving it clockwise and counter clockwise. The motor just moves a set amount of degrees until it hits a limit switch, waits for input and then moves the reverse direction until it hits another limit switch.
Yesterday, when I was testing it, I forgot that I had the armature locked in a safety position and the motor tried it's hardest to move but couldn't. After 5 or so seconds, the power and ground wires from the power supply to the speed controller smoked and melted. After replacing those two wires, everything still works so no real damage. Granted, those two wires were 22 or 24 gauge, while everything else is heavier in the 14-18 range.
To prevent this from happening in the future—or more likely something getting stuck under the animatronic before it can hit it's limit switch—I should just put a fuse between the power supply and speed controller, right? Is there a good way to figure out what value fuse i'd need? Or perhaps there's something else i'm missing.
As a general rule single core wire can handle more load. For example; 12-14 gage wire stranded can typically handle 10-15 amp, and single core 25-35 amp load. So a lot depends on the quality/type of wire used. I would look at the output rating of your power supply and adjust the fuse rating to that so you don't accidentally cook your PS.