– Ensure that another person, familiar with the
power-off controls, is near you.
Attention: Another person must be there to switch
off the power, if necessary.
– Use only one hand when working with powered-on
electrical equipment; keep the other hand in your
pocket or behind your back.
Attention: An electrical shock can occur only when
there is a complete circuit. By observing the above
rule, you may prevent a current from passing through
your body.
– When using testers, set the controls correctly and
use the approved probe leads and accessories for
that tester.
– Stand on suitable rubber mats (obtained locally, if
necessary) to insulate you from grounds such as

metal floor strips and machine frames.

Observe the special safety precautions when you work
with very high voltages; Instructions for these
precautions are in the safety sections of maintenance
information. Use extreme care when measuring high
voltages.
v Regularly inspect and maintain your electrical hand tools
for safe operational condition.
v Do not use worn or broken tools and testers.

v Never assume that power has been disconnected from

a circuit. First, check that it has been powered off.
v Always look carefully for possible hazards in your work
area. Examples of these hazards are moist floors,
nongrounded power extension cables, power surges,
and missing safety grounds.
v Do not touch live electrical circuits with the reflective
surface of a plastic dental mirror. The surface is
conductive; such touching can cause personal injury and
machine damage.

v Do not service the following parts with the power on

when they are removed from their normal operating
places in a machine:
– Power supply units
– Pumps
– Blowers and fans

– Motor generators

and similar units. (This practice ensures correct

grounding of the units.)
v If an electrical accident occurs:
– Use caution; do not become a victim yourself.
– Switch off power.

– Send another person to get medical aid.

Safety information
18 R50/R50p, R51 Series