A double tapped electrical circuit breaker is where two or sometime more electrical conductors (wires) are improperly connected to the same terminal in a circuit breaker that is designed by the manufacturer to only accommodate one conductor. This should be considered a safety hazard for the following reasons:
Overloading: Double tapping can overload the circuit breaker. If it is designed to only accommodate a single conductor, then the combined current from two conductors might exceed the circuit breaker's capacity, potentially causing it to trip or even lead to a fire hazard.
Loose Connections: Double tapping can cause connections to become loose over time due to the extra stress on the terminal and the fact that it is only designed for one conductor. Loose connections can generate heat, potentially melting insulation or causing arcing - a cause of electrical fires.
Code Violation: Commonly accepted practices and electrical codes do not allow double tapping.
Reduced Contact Area: Having two conductors in a single terminal reduces the contact area between the conductor and the terminal, leading to increased resistance and heat generation.
Since identifying a double tapped circuit breaker involves removing the electrical panel cover, we do not recommend attempting to identify and correct double tapped circuit breakers on your own. The identification and correction of double tapped circuit breakers should be left to a licensed electrical contractor. The electrical contractor may recommend one of the following remedies:
Installing a tandem circuit breaker (also called split, twin, or double breakers). They have two separate circuits in the space of a regular-sized breaker slot. This type of breaker does have some limitations. The tandem breaker manufacturer should be compatible with the panel manufacturer.
Installing a pig tail connection where the existing conductors are disconnected from the circuit breaker and then connected to a single conductor with a wire nut. The single conductor the is connected to the circuit breaker.
Installing a circuit breaker that is designed to accommodate two conductors. Not all panel manufacturers manufacture breakers that can accommodate two conductors. The breaker manufacturer should be compatible with the panel manufacturer.
If none of the above remedies are possible as a last resort an electrical sub panel would need to be installed. This may especially be the case where there are multiple double taps present.