Based on the 2020 NEC
Q. What is the Code rule for the marking of disconnects?
See answer below.
A. As noted in Sec. 110.22(A), each disconnect must be legibly marked to indicate its purpose unless located and arranged so the purpose is evident. In other than one- or two-family dwellings, the marking must include the identification of the circuit source that supplies the disconnecting means. The marking must be of sufficient durability to withstand the environment involved.(Figure).
See Sec. 408.4 for additional requirements for identification markings on circuit directories for switchboards and panelboards.
These rules are intended to make it safer to work on electrical equipment. The premise is that if the worker knows the location of the power source, he or she is much more likely than not to lockout and tagout the power source.
These materials are provided to us by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code.
