One fundamental safety-related work practice is that exposed, live electrical parts must be de-energized before work on or near them is permitted. The only exception to this rule is when a qualified person is available and it is absolutely necessary due to equipment design or operational limitations. If this happens, other work practices must be followed to protect that person. The bottom line is that all of us, including unqualified and qualified persons, must protect ourselves from all potential contact with live electrical parts. Protection may be provided via shielding, insulated tools, or protective electrical gloves and clothing.
To properly isolate electrical energy and prevent exposure to electrical hazards, the system or its parts must be locked or tagged out in accordance with your company Lockout/Tagout Policy.
Lockout is defined as the placement of a lockout or tagout device on an energy-isolating device, such as an electrical disconnect switch, in accordance with a written procedure. This is performed to ensure that the isolating device will be controlled from inadvertent or accidental operation until all employees are safe and the lockout/tagout device is removed.
Regarding work on an electrical system, a lock with a tag must be placed on all disconnecting devices. The lock must be securely attached and locked. The tag must contain a statement prohibiting energization or operation of the equipment and removal of the tag. In addition, a qualified person MUST test the equipment to verify that the circuit elements and parts that are isolated are in fact de-energized. Electrical equipment should never just be presumed to be dead; verification is always necessary. If the electrical system is over 600 volts, the test equipment used by the qualified person must be checked immediately before and after to assure proper operation.
A very important safety procedure is the re-energization of electrical disconnect switches. If an electrical malfunction should occur, it is critical that you and other employees are clear of the electrical equipment. Never stand in front of a disconnect switch when you are energizing the circuit. Proper closing or activation of switches means that you always stand to the un-hinged side of the cabinet. Close the switch with your near hand or arm and turn your head away from the cabinet. This is done to reduce the risk of injury in case of a malfunction of the switch starter, which could cause the release of an arc of energy. Although this is a rare occurrence, it can and does happen. If this were to occur, you could be struck by the cabinet door and seriously burned by the intense electrical arc.