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What is the difference between a parallel arc fault and a series arc fault?

Issue:
What is classified as a parallel and a series arc fault?

Product Line:
Miniature Molded Case Circuit Breakers

Environment:
QO and Homeline AFCI Circuit Breakers

Resolution:
A parallel arc occurs when electricity intermittently jumps a gap between wires of different voltages, such as Line to Line (2 hot conductors of different phases), Line to Neutral, or Line to Ground. An example of what may cause a parallel arc is a nail protruding through drywall, damaging the wire in the wall and exposing the hot and neutral wires. If the damaged wires are close enough together, an arc may occur between the exposed wires. Because a parallel arc occurs between conductors at different voltages, the amount of current can vary widely, from very little to a very high amount (up the short-circuit current available for that circuit).

A series arc occurs when electricity intermittently jumps a gap between two or more points within the same phase. An example of what may cause a series arc is if a wire is only loosely connected under the screw terminal of a wall switch, and there are very small gaps between the wire and the terminal. If the gap is small enough, an arc may occur between the wire and terminal. Because a series arc occurs within the same phase,  the amount of current is no higher than the load current itself.
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