Method and apparatus for protecting electrical systems

An electrical system, comprising:

• a) a central mains inlet;
• b) a plurality of mains conductors;
• c) a central ground fault detector/interrupter connected to the central mains inlet via the plurality of mains conductors, the central ground fault detector/interrupter including:
• 1) a central ground fault detector for detecting current imbalance between the mains conductors;
• 2) a central ground fault interrupter being actuatable when said central ground fault detector detects a first predetermined level of current imbalance to interrupt the central mains inlet;
• d) a plurality of local electrical devices connected to each of said mains conductors;
• e) a plurality of local safety systems each being connected to one of the plurality of local electrical devices and the mains conductors, each of said local safety systems including:
• 1) a local ground fault detector for detecting in a respective local electrical device a current imbalance of a second predetermined level which is lower than said first predetermined level, wherein each local safety system includes means for producing an audible alarm when the local ground fault detector has detected a third predetermined level of current imbalance lower than the first level, and means for producing a visible indication upon detection of a fourth predetermined level of current imbalance lower than the third level;
• and
• 2) a local circuit interrupter for interrupting power supplied from the central mains inlet to a respective local electrical device when the local ground fault detector detects the second predetermined level of current imbalance;
• f) control means for actuating the central ground fault interrupter to interrupt the central mains inlet when one of the local ground fault detectors detects the second predetermined level of current imbalance in one of the plurality of local electrical devices.

An apparatus for providing protection against electrical shock caused by an electrical system, the electrical system supplying power from a central mains inlet to at least one of a plurality of local electrical devices via a plurality of mains conductors, the central mains inlet being connected to a central ground fault detector and a central ground fault interrupter, the central ground fault detector detecting current imbalance between the plurality of mains conductors, the central ground fault interrupter being actuated when said central ground fault detector detects a first predetermined level of current imbalance to interrupt the central mains inlet, the apparatus comprising:

• a) a plurality of local safety systems each being connected to one of said plurality of local electrical devices and the central mains inlet, each of said local safety systems including:
• 1) a local ground fault detector for detecting in said one local electrical device a current imbalance of a second predetermined level which is lower than the first predetermined level;
• and
• 2) a local circuit interrupter for interrupting said one local electrical device when the local ground fault detector detects said second predetermined level of current imbalance;
• b) means for creating an increased current imbalance between the mains conductors that is equal to or greater than said first predetermined level in response to one of said local circuit interrupters interrupting a respective local electric device, wherein the central ground fault detector detects the increased current imbalance and causes the central ground fault interrupter to interrupt said central mains inlet.

An apparatus for providing protection against electrical shock caused by an electrical system, the electrical system supplying power from a central mains inlet to at least one of a plurality of local electrical devices via a plurality of mains conductors, the central mains inlet being connected to a central ground fault detector and a central ground fault interrupter, the central ground fault detector detecting current imbalance between the plurality of mains conductors, the central ground fault interrupter being actuated when said central ground fault detector detects a first predetermined level of current imbalance to interrupt the central mains inlet, the apparatus comprising:

• a) a plurality of local safety systems each being connected to one of said plurality of local electrical devices and the central mains inlet, each of said local safety systems including:
• 1) a local ground fault detector for detecting in said one local electrical device a current imbalance of a second predetermined level which is lower than the first predetermined level and for outputting a control signal;
• 2) a local circuit interrupter for interrupting said one local electrical device when the local ground fault detector detects said second predetermined level of current imbalance;
• and
• 3) a booster unit for receiving said control signal and in response thereto, increasing the current imbalance between the mains conductors to be equal to or greater than said first predetermined level thereby actuating the central ground fault interrupter to interrupt said central mains inlet.