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Prevention of electric shocks
Before starting work, make sure that, unless otherwise specifically instructed, there is
no potential electric hazard in the maintenance area such as insufficient grounding or
a wet floor.
Before starting work, note where the emergency power-off switches are located and
make sure you know how to operate them.
Unless otherwise specifically instructed, cut off all power sources to the machine
before starting maintenance. Just switching off the machine power supplies is usually
not enough.
When power is fed from a wall or floor outlet, unplug the power supply cord, or turn
off the switch on the power distribution panel or board. Attach a notice on the panel
or board prohibiting the use of the switch.
If the energy isolating device such as the switch on the power distribution panel or
board accepts a lockout device, turn off the power, lock out the energy isolating
device, and bring the key with you. When you take over the work and the key for the
lockout device if applicable, do not assume that the power is off. Make sure yourself
that the above-mentioned conditions such as switches are satisfied. If necessary,
use a measurement tool to ensure that the power is off.
Do not touch any uninsulated conductor or surface, where so instructed, which
remains charged for a limited time after the external power supply to the machine is
disconnected.
When working on a machine which has a grounding terminal, make sure that the
terminal is properly connected to the facility's ground.
When working close to a hazardously energized part, do not work alone; work with
another person who can immediately turn off the power in an emergency.
Do not wear any metallic item such as a wrist watch with a metallic surface, or
metallic accessories.
If you wear eyeglasses with a metallic frame, take care not to let the frame touch an
uninsulated surface.
Make sure that your hands and arms are dry.
Unless otherwise specifically instructed, use only one hand when it is necessary to
work near an exposed live electric circuit.
This prevents the completion of the circuit through your heart even if you accidentally
touch the circuit.
Do not use a dental mirror near an exposed live electric circuit.
The mirror surface is conductive and can become hazardous even if it is made of
plastic.
Unless otherwise specifically instructed, do not supply power to any subassembly
such as a power supply unit or a motor while it is removed from the machine.
S-4
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