Extech Instruments 7470 Operation Manual page 17

Compliance agency requirements vary on how different products are to be tested.
Most specifications call for test currents of between 10 and 30 amps. Test voltages at
these currents are typically required to be less than 12 volts. Maximum allowable
resistance readings of the safety ground circuit are normally between 100 and 200
milliohms.
If you are testing a product that is terminated in a three-prong plug, you are required to
perform a continuity or ground bond test on the ground conductor to the chassis or
dead metal of the product.
1.6.4. Run Test
All manufacturers of a product that runs on line power normally need to run the DUT
(Device Under Test) after final safety testing so that they can verify the functionality of
their products. In addition to running the DUT to test its basic functionality many
customers also require some basic test data to be recorded while the DUT is powered
up. A Run Test System allows the product to be powered up immediately after the
safety tests are completed with a single connection to the DUT. Measurements that
are commonly made while the DUT is running can include Amperage, Voltage, Watts
and Power Factor.
1.6.5. Line Leakage Test
The Line Leakage test is one of many product safety tests that are normally specified
for electrical products by safety testing agencies such as Underwriters Laboratories (UL)
and the International Electrotechnical Committee (IEC). The line leakage
specifications vary as well as the method in which the measurements are taken
depending upon the application or function of a product and the standard to which the
product is being tested.
Current Leakage or Line Leakage tests are general terms that actually describe three
different types of tests. These tests are Earth Leakage Current, Enclosure Leakage
Current, and Applied Part Leakage Current. The main differences in these tests are in
the placement of the probe for the measuring device. The Earth Leakage Current is
the leakage current that flows through the ground conductor in the line cord back to
earth. The Enclosure Leakage Current is the current that flows from any enclosure
part through a person back to ground if it were contacted by a person. The Applied
Part Leakage Current or Patient Lead Leakage Current is any leakage that flows from
an applied part, between applied parts or into an applied part. The Applied Part
Leakage Current test is required only for medical equipment. All of these tests are
used to determine if products can be safely operated or handled without posing a shock
hazard to the user.
Line Leakage Testers provide the capability of meeting the line leakage test specified in
the following standards; UL 544, IEC 950, UL 1950, IEC 601-1, UL 2601, UL 1563, UL
3101, IEC 1010 and others. The Line Leakage test, is a test which measures the
leakage current of a product, through a circuit that is designed to simulate the
impedance of the human body. The simulation circuit is called the Measuring Device
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