Abstract: A protection circuit is provided which incorporates a reed relay whose contacts form the circuit breaker of an electrical appliance. The winding of the reed relay is supplied with a rectified alternating current derived from a current transformer coupled to the supply line to the appliance. In order to avoid periods of zero current in the winding, the winding is also supplied with a rectified alternating current from a source which is out of phase with that supplying the supply line. Failure of the current on the line will cause the contacts to open. Preferably the relay has a set of self latching contacts to prevent re-energization of the winding once de-energized. A manually operable reset switch is provided in series with the self latching contacts.