Originally Posted By: Dennis Bozek
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Thanx for clarifying that David.
Just a word of caution here. Sticking anything into a electrical panel that is non-insulated is better left to the pros.
Wire gauge is difficult to determine and even I have a difficult time with it for although I can make a educated guess
without actually seeing a mark on the wire or having a specific tool to gauge it, it should not be guessed at. The code allows 4 gauge to be used for a 100 amp service in a house although I would always run 3. Nevertheless, the two are so close in size, it would be easy to mess it up. What you can usually do, and I would suggest a good pair of gloves prior to doing this or at least some hot gloves, is to actually turn the wire on the main breaker and see if you can see any writing on it. If you can look for that AWG marking. Right before that if will give you the wire size. If it is SE cable, the gray or black insulation on it will be marked but sometimes with this it is impressed into the insulation making it quite hard to read. You can also pull the LB cover off and look at the wire there. If you get lucky sometimes you can read the gauge on the wire at that point.
Purchase a inspection mirror, which is usually a small round mirror on a thin metal handle. Get some electrical tape and tape the metal parts of the inspection mirror a few times. This will aide in not shorting against anything as you insert it into the panel. You can use this mirror at times to read wire gauge if the wire cannot easily be turned to read it.
The only real problems I have with using a wire stripper is that usually anything above 6 gauge is not available on a stripper and that it is dangerous to do such if you are not familiar with all the dangers a electrical panel exposes to you.
This information has been edited and reviewed for errors by your favorite resident sparky.