Text in force at 23-63: from 23-0, effective 1 Feb 1965.
Each switch must be--
(a) Able to carry its rated current;
(b) Constructed with enough distance or insulating material between current carrying parts and the housing so that vibration in flight will not cause shorting;
(c) Accessible to appropriate flight crewmembers; and
(d) Labeled as to operation and the circuit controlled.
29 FR 17955 · Source