MSHA - Code of Federal Regulations - 30 CFR 57.4502
30 CFR § 57.4502
(a) Battery-charging stations shall be ventilated with a sufficient volume of
air to prevent the accumulation of hydrogen gas.
(b) Smoking, use of open flames, or other activities that could create an
ignition source shall be prohibited at the battery charging station during
(c) Readily visible signs prohibiting smoking or open flames shall be posted
at battery-charging stations during battery charging.