I was e-mailed an interesting question recently concerning some of the following circuit breaker lockouts. The question was, "Aren't some of these lockouts illegal because the circuit breaker can be locked in the 'CLOSED' or 'ON' position?"

Consider the following:

1 - You are required to check for the presence of voltage on the locked out and tagged out circuit before any work is begun. If you lock the breaker or disconnect in the "ON" position you are not focused on the task at hand...but you will soon be!

Verification of isolation: Before any work begins on machines or equipment that have been locked out or tagged out, an authorized employee must verify that the machine or equipment has been properly isolated and deenergized. (See Application of Energy Control)

2 - The National Electrical Code® (NFPA 70) 2005 edition - Section 240.80 reads, "Circuit breakers shall be trip free and capable of being closed and opened by manual operation." The NEC does not define "trip free" but an internet search will provide you with a great deal of information.

One source defines 'trip free' as - "...a circuit breaker that will trip (open) even if the operating mechanism (ON-OFF switch) is held in the ON position."

Another source - "A trip-free circuit breaker cannot be held closed during a fault - the switching mechanism will not be defeated by forcibly holding the actuator on. In a fully trip-free design, the main contacts will remain open after a fault when the actuator is held in the "on" position. Some devices, known as "cycling trip-free" circuit breakers, cannot be forcibly held on during a fault, but they will cycle on and off if the actuator is held in the "on" position. A trip-free circuit breaker should be used if the circuit breaker is mounted in an easily accessible (that is, not enclosed) place."

3 - Some Authorities Having Jurisdiction require that the circuit breaker protecting the control voltage for the elevator main line power supply shunt trip device be locked in the "CLOSED" ("ON") position because it could be accidentally opened and the shunt trip device would fail to operate as intended in an emergency. The most recent editions of the NFPA 72 National Fire Alarm Code® require that this voltage be monitored and annunciated.

2002 Edition

2007 Edition

Below is a miniature circuit breaker and the data sheet for an Automation Systems Interconnect, Inc. Circuit Breaker Lockout Assembly.

ASI Circuit Breaker Lockout Assembly
Image from: Automation Systems Interconnect, Inc.