IBM System/36 Maintenance Information Manual page 9

Electrical Safety
• Always disconnect the power cord before you work on a machine.
Note: A non-IBM attachment to an IBM machine may be powered from another source and may be
controlled by a different switch or circuit breaker.
• Switch off all power and disconnect the power cord before:
Removing or assembling the main units of the equipment.
Working near power supplies.
Inspecting power supplies.
Installing changes in machine circuits.
Connecting cables between equipment.
• Do not connect cables during an electrical storm.
• If you really need to work on equipment that has exposed live electrical circuits, observe the following
precautions:
Ensure that another person who understands the power-off controls is near you. Another person
must be there to switch off the power, if necessary.
Do not wear jewelry, chains, metal-frame eyeglasses, or other personal metal objects. Remember, if
the metal touches the machine, the flow of current increases because the metal is a conductor.
Use only insulated probe tips or extenders. Remember, worn or cracked insulation is unsafe.
Use only one hand while you are working on live equipment. Keep the other hand in your pocket or
behind your back. Remember, there must be a complete circuit for an electrical shock to occur.
This precaution prevents your body from completing the circuit.
When you use a tester, set its controls correctly and use insulated probes that have the correct
electrical specification.
Do not touch objects that are grounded, such as metal floor strips, machine frames, or other
conductors. Use suitable rubber mats obtained locally, if necessary.
• Never assume that power has been removed from a circuit. First, ensure that power has been removed.
• If an electrical accident occurs:
Use caution. Do not be a victim yourself.
Remove the power plug from the customer outlet.
Obtain immediate medical aid.
Safety ix