6 December 2006
Including change 1, 7 December 2006
LOW-VOLTAGE INTERIOR SYSTEMS
WORKING ON INDOOR EQUIPMENT.
Restricted Space. Be alert that older installations might not meet current
NEC clearance and entrance requirements for electrical rooms. Where installations do
not conform to current NEC/OSHA requirements, additional safety precautions and
instruction must be provided to maintenance workers. Give special attention to the
guarding of live parts where current NEC clearances are not met. Ensure that
unobstructed emergency exit routes are provided.
Grounding Systems. Verify that existing permanent electrical system
grounds are adequate for personnel protective grounding, and provide additional
temporary grounding as necessary.
Disconnection of Power Sources. Be sure to check single line diagrams
and verify that all inputs and interconnections to any electric power source are locked
and tagged open. Verify single line diagram connections with the actual line
connections of the applicable equipment.
Related Building Systems. Do not disable or work on any fire protection
and fire alarm systems without prior notification and approval of the local fire
department. If the room's ventilation system is affected by the work, ensure that
adequate temporary ventilation is provided.
12-2.1.1 Complete any work with only qualified electrical workers with training and
experience on low-voltage circuits. Electrical workers must be familiar with NEC
requirements and must have work experience with low-voltage systems. Inform the
foreman when installations do not meet the requirements of applicable codes and
standards, such as the NEC. Electrical workers must understand electrical safety
requirements for low-voltage systems.
12-2.1.2 Consult the manufacturer's instruction manual if available for the apparatus
before starting work.
12-2.1.3 Unless specifically approved, work is not permitted on energized circuits. Use
temporary ground wires to drain off induced voltages and currents from live circuits,
stored energy devices, and equipment metal guards before starting work.