wire gauge tester tool

Does anyone have a good wire gauge tester tool they use they can recommend. I am always questioning myself on the wire gauge of branch circuits in a panel. I would like something that I can place on the wire itself to determine its size. Thanks.

I made a small cardboard display with all the wire sizes on it. Actually wires and insulation glued onto cardboard. Used it my first few years.

I also have a wire chart on my clipboard, colored from code check.

For service sizes, make sure you use table 310-15 rather than 310-16 which is what that guide is.


Nice table. I would note that this table is good for Interior SE and NM cable and residential services. Wiring methods other than NM and interior SE cable in sizes smaller than #1/0 can often utilize the 75° C rating of the conductors in Table 310.16 if the terminations are rated for 75° C as well.