Question: Can the disconnect switches be locked in the closed (on) position?
Response: There is no provision in the OSHA regulations that prohibits locking the disconnecting means in the closed (on) position. The OSHA rule at 29 CFR 1910.304(d)(1) requires that "the disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point-of-entrance of service-entrance conductors." In accordance with 29 CFR 1910.399, readily accessible is defined as "capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc." The definition of readily accessible does not preclude the use of a locked door for service equipment or the use of a lock on the disconnecting means, provided those for whom ready access may be necessary have a key (or lock combination) available. Please note, however, that the use of multiple locks or keys on disconnecting switches may preclude the installation from being readily accessible.