I'm going to be replacing an old surface mounted 100amp combination panel that replaced a much older panel many years ago.

The owner tells me that the house is wired with cloth and rubber, but all the wire in the panel looks to be at least tw or possibly even thhn.

Now that the code demands that we tie the handles of circuits that share a neutral, I am scratching my head. In two places circuits leave the panel with four hots and two neutrals.

I don't have the first clue as how to figure which are the hots that go with the particular neutral.