before labeling my fuse panel i wanted to double check wire gauge. i ended up making a 3/16'' wide strip of .o32 aluminum 4'' long. i put a slot in the end with the bandsaw and then opened the gap so that it would just slide over 20 ga. wire. won't fit over 18 ga. and 22ga falls in the gap. you don't even need 1/2'' of the wire accessable to check it.