30 CFR § 77.513
Insulating mats at power switches.
Dry wooden platforms, insulating mats, or other electrically nonconductive
material shall be kept in place at all switchboards and power-control
switches where shock hazards exist. However, metal plates on which a person
normally would stand and which are kept at the same potential as the
grounded, metal, non-current-carrying parts of the power switches to be
operated may be used.