30 CFR § 57.12020
Protection of persons at switchgear.
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.
For more information: See MSHA'S Program Policy Manual