I bought a house in Southern NH in March. had a couple of hints that the previous owner did his own wiring..
1. Changed out the dryer circuit from a 3 prong recept , fed by a piece of 12/2 UF cable, to a 4 prong fed with 10/3 romex
2. Three way switches, both lights go on, then one light shuts off, then the other light shuts off.
3. Basement is finished, replaced the old 4in halogen recessed with new 6" LED wafers. the box attached is a sample of the work, a mixture of 14/2 and 12/2 romex spliced together . He intercepted the 1st floor bathroom GFCI circuit and wired the basement lighting off of it.
4. Basement wall receptacles were half constant, half controlled by the same dimmer which controlled the recessed lighting!!! If anyone ever plugged in anything electronic.....fried !!
5. old hot tub fed with 8/3 on a 50A breaker. Should be 6/3
6. electric floor heat doesn't work....that's on the list