Section 110.22 requires each disconnect to be legibly marked with its purpose unless that purpose is evident from the location and arrangement of the disconnect. Some people assume the use of the word "legibly" is a holdover from the days when handwritten signs were considered acceptable, and anything not handwritten complies with the legibility requirement. That assumption is false. In fact, signage or markings can be illegible if stenciled or stamped on a tag or directly on the disconnect.

Here are some ways this might happen:

  • The sign material isn't durable in the environment it's being used in. A plastic laminate might curl or separate due to heat, a fiber-based material might decompose, and metal might corrode. There is no ideal material; there is only material suitable for a given environment.
  • The lettering (e.g., paint or ink) isn't durable in the environment or doesn't stay on the sign material (or body of the disconnect).
  • The means of sign attachment isn't durable (e.g., hung with string instead of wire).
  • The printing is too small.
  • The lighting makes the lettering hard to read. Stainless steel stamped tags are prone to this problem.
What's implied but not stated is the marking must be readily visible. If you must hunt for the label, the goal of Section 110.22 is defeated.