Double Tapping is when multiple wires are connected to a single breaker. There are some breakers that can safely accommodate multiple wires, but most breakers are not rated for this. For example, Square D breakers commonly have two slots that enable one wire to fit into each slot, safely accommodating two wires. However, most breakers don’t have these slots and instead use the lug to secure one wire. If two wires are installed under a single lug, it is possible that one or both wires could become loose thus creating an arcing hazard.