No employee shall be permitted to work in such proximity to any part of an electrical power circuit that he may contact in the course of his work unless he is protected against shock by de-energizing the circuit, grounding it, or guarding it by effective insulation. If protection is supplied by de-energizing the circuit, the switch controlling the circuit shall be locked out to prevent inadvertent closing.
Okla. Admin. Code § 380:55-3-8