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What type of field wiring can I use on Molded Case Circuit Breaker terminals?

For field wiring that is to be landed on molded case circuit breaker terminals, and what types of wiring are compatible with those breaker terminals. UL 489, the standard to which molded case circuit breakers are built, references UL 486A-486B for wiring and termination issues. 

Generally, wire or cable allowed to be used with UL 489 rated circuit breakers is somewhat limited in type. This turns out to be primarily a safety issue.

In order to be compliant with UL, NEMA, and NEC recommendations, field wiring to standard molded case circuit breaker terminals has to be completed using appropriate single-input wire (SIW), class B wire, or class C wire.

Locomotive wire, welding wire, high flex wire, high strand wire, etc., all those types are highly flexible wire, and fall outside the guidelines of what is acceptable to land on the breaker terminal, itself.  With highly flexible wire of all types, breakage of individual strands is a concern, as is “pull out,” after the wire is secured in the terminal.  That is not to say there is no solution for you to leverage in wiring to a breaker using that type wire, but you will have to invoke use of an acceptable option for wire termination in doing so.

It is always proper to land field wiring on molded case circuit breakers using just one conductor secured in the breaker terminal.  Solid core wire of an appropriate size is recommended for use in wiring to molded case circuit (and residential) circuit breakers.  This also means high strand wire, with a ferrule rated for use with that wire type crimped on the end of the wire, could be secured in a standard terminal (a ferrule will effectively present just one piece of wire, not multiple strands, to the breaker terminal).  Another option to secure high strand wire to a breaker would be for the customer to procure an appropriately rated compression terminal, such as a ring tongue terminal, crimp that on the end of their high strand wire, and then bolt that compression terminal to the breaker through use of an end cap kit, keeper nut, or plug nut.  Eaton does not offer any kind of ferrule or compression terminal for sale – those must be procured locally by the customer.