I install new 12/2 wire from breaker box to a gfi outlet pig tail to another gfi outlet then to seven regular outlets then jumped to a light switch controlly six can light(6 inch).light switch is a dimmer ,everything was working fine for about one week then the can light quit working all the outlet still work but lights won't come on. All wires are 12/2 on a 20amp breaker. The first gfi show on my yellow plug in tester open ground. I have checked the wires and they look ok.I was hoping someone could tell me what is wrong
Some dimmers (and other "smart" switches), require a grounding conductor to function. If there's an open ground, the receptacles will function normally, but the dimmer may not.
To test this theory, replace the dimmer with a standard snap switch. If the lights work with the new switch, the problem was an open ground. Find the break in the grounding conductor, and your problem should be solved.