Double tapping is one of the most common electrical defects we find during a standard home inspection. Double tapping is defined as two or more wires installed in a breaker that is only rated for one wire. There are two instances where this commonly occurs; 1. On standard 120 or 240 volt breakers and 2. Less often on the main breaker.
Main breaker double tapping is the most dangerous. It usually involves adding an addition sub panel supplied by a wire tied to the
incoming service. Without the protection of a breaker or fuse this is very dangerous. In the example to the right what appears to be a #8 wire which normally would be protected by a 40 amp breaker; is tied directly to the utility service. It is not protected at all until it reaches the sub panel. This is a very serious safety hazard. This could easily be corrected by moving the wires for the sub panel to the open space in the box and installing a proper sized breaker for the wire used.
Some breakers such as this “Square D Homeline” breaker on the left are listed to handle two wires at one time. Note the designation of
1 AlCu and 2 Cu indicating you may install one copper coated aluminum wire or 2 copper wires. Two copper wires maybe used as long as each individual wire is properly sized and positioned under the tension clip. Unless your breakers are marked in this manner you should not put more than one wire under the screw of the breaker.
If you have double tapped breakers you should employ the services of a qualified electrician. An electrician may easily correct this problem by using a pig tail to reduce the number of wires per breaker. A better alternative is to use a piggy back breaker if the panel is designed to accept them.
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