8
4.
OPERATION
All power line circuits contain voltages constituting a shock hazard that can be
lethal (refer to Shock Hazard definition on page 3 of manual). This Instrument
was designed to prevent accidental shock to the operator. However, exceeding
its capabilities, or using it carelessly, can be dangerous. Review the Safety
Precautions listed below. Make sure you understand them and observe them
when using this Instrument.
This section of the manual contains all the information related to operation of the
Instrument.
4.1
Safety Precautions
1.
The Model 390-2 is intended for use by personnel who are qualified to
recognize shock hazards and trained in the safety precautions needed to
avoid possible injury. Refer to the “SHOCK HAZARD” definition on page 3 of
this manual.
2.
Do not work alone when measuring where a shock hazard might exist. Notify
someone that you are making, or intend to make, such measurements.
3.
Locate all voltage sources and accessible current paths before making cir-
cuit connections. Be sure the equipment being tested is properly grounded
(if that is its normal mode of operation), and that its fuse(s) are of the correct
type and rating. Make certain the test leads are connected to the proper input
jacks before applying power.
4.
Make sure work area, as well as hands and shoes, are dry.
5.
Avoid making tests and measurements under humid, damp, or other envi-
ronmental conditions that could affect the dielectric withstanding voltage of
the test equipment.
6.
Do not touch “live circuits” or any object that could provide a current path to
the common side of the circuit under test or power line ground.
7.
Use a 3-wire power line outlet that is correctly wired in accordance with the
latest National Electrical Code. If you are not certain that the power outlet
meets these requirements, use a 3-wire to 2-wire adapter plug, and ground
the wire from the adapter to a known good earth ground.
8.
When using the special test lead set without the break-in plug, shut off the
power to the circuit before making clip connections.
9.
When testing a 240-VAC line-operated device, make up a 120-240 VAC
adapter set as shown in Figure 4-4 on page 13. Be sure the outlet used is
correctly wired as discussed in number seven above.
4.2
Zero Setting Of Meters
1.
Before you use your Instrument, be sure that the pointer is on zero when
there is no power applied. A zero adjust screw is located directly below the
meter scale (see Figure 3-1 on page 7).
2.
Use a screwdriver to rotate the screw either clockwise or counterclockwise
until the knife-edge pointer rests over the zero indication at the left hand side
of the scale.
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