Garbage disposal wiring problem

Elton Smith · Nov 10, 2019

I bought a garbage disposal and had it installed under the sink by a plumber. When we attach it to the power, if the switch is turned on the disposal runs. When the switch is turned off, it trips the circuit breaker. I tried attaching a different switch, but it still has the problem. The clothes washer is plugged into this same circuit and works fine.

Devonchris · Nov 11, 2019

If it its a GFCI (or RCD) that is tripping, but is holding when the switch is closed, then there is no imbalance in the circuit. If a double pole switch is fitted, and one pole is opening very slightly before the other then a imbalance will be detected and the device will trip.

But until the op comes back and confirms what's involved then we can only speculate.

Megawatt · Nov 11, 2019

Devonchris said:
If it its a GFCI (or RCD) that is tripping, but is holding when the switch is closed, then there is no imbalance in the circuit. If a double pole switch is fitted, and one pole is opening very slightly before the other then a imbalance will be detected and the device will trip.

But until the op comes back and confirms what's involved then we can only speculate.

@Devon he stated it was on the same circuit as the refrigerator. That branch circuit is required to be installed as a dedicated circuit by the NEC and no GFCI is required. Having said that the plumber has tapped off that circuit which is not allowed. VIOLATION

DPG · Nov 12, 2019

Devonchris said:
If it its a GFCI (or RCD) that is tripping, but is holding when the switch is closed, then there is no imbalance in the circuit. If a double pole switch is fitted, and one pole is opening very slightly before the other then a imbalance will be detected and the device will trip.

But until the op comes back and confirms what's involved then we can only speculate.

I think the OP confirmed that it's the 30A MCB that's tripping.