IBM 3279 2A Maintenance Information page 7

3279 MIM
Safety Guidelines
If you are aware of the guidelines for working
with electrical and mechanical equipment and
practice these guidelines, you can work safely
with this equipment.
You need. not fear electricity, but you must
respect it.
You should take every safety precaution
possible and observe the following safety
pactices while 'maintaining IBM equipment:
1. You should not work alone under hazardous
conditions or around equipment with
dangerous voltage. Always advise your
manager if this is a potential problem.
2. Remove all power before removing or
assembling major components, working in
the immediate area of power supplies,
performing mechanical inspection of power
supplies, or installing changes in machine
Circuitry.
3. Power supplies, pumps, blowers, motor
generators, and other units with voltages
Which exceed 30 V ac or 42.4 V dc must not
be serviced with power on when the unit is
removed from its normal installed position
within the machine, unless maintenance
documentation clearly states otherwise.
(This is done to ensure that proper
grounding is maintained.)
4. Unplug the power supply cord whenever
possible before working on the machine.
The wall box switch when turned off should
be locked in the off position or tagged with
a DO NOT OPERATE tag (form Z229-0237).
Be aware that a non-IBM attachment to an
IBM machine may be powered from another
source and be controlled by a different
disconnect or circuit breaker.
5. When it is absolutely necessary to work on
equipment having exposed live electrical
circuitry, observe the following precautions:
a. Another person familiar with power off
controls must be in immediate vicinity.
(Someone must be there to turn off
power if it should become necessary.)
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b. Do not wear any jewelry, chains, metallic
frame eyeglasses, or metal cuff links. (In
the event of contact, there will be more
current flowing because of the greater
contact area afforded by the metaL)
c. Use only insulated pliers, screwdrivers,
and appropriate probe tips/ extenders.
(Remember, worn or cracked insulation is
unsafe.)
d. Use only one hand when working on
energized equipment. Keep the other
hand in your pocket or behind your back.
(Remember there must be a complete
circuit for electrical shock. This
procedure helps eliminate a path that
could complete a circuit through you!)
e. When using test equipment, be certain
that controls are set correctly and that
insulated probes of proper capacity are
used.
f. Avoid contacting ground potential (metal
floor strips, machine frames, etc.). use
suitable rubber mats purchased locally if
necessary.
6. Follow special safety instructions when
working with extremely high voltages.
These instructions are outlined in CEMs and
the safety portion of maintenance
documentation. Use extreme care when
checking high voltage.
7. Avoid use of tools and test equipment that
have not been apPllf)ved by IBM. (Electrical
hand tools [wire wrap guns, drills, etc.]
should be inspected periodically.)
8. Replace worn or broken tools and test
equipment.
9. -After maintenance, restore all safety devices,
such as guards, shields, signs, and ground
leads. Replace any safety device that is
worn or .defective. (These safety devices
are there to protect you from a hazard.
Don't defeat their purpose by not replacing
them at the completion of the service call.)