PRODUCT SAFETY SOLUTIONS
© 2012 Educated Design & Development, Inc. All rights reserved. Rev B: February, 2012
Page 3 of 19
The LT-952 is designed to test any single-phase product rated 100-120 or 200-240 Volts that requires
15 Amps or less current.
True 15 Amp open neutral, open ground, and line polarity (forward/reverse) test conditions.
120V front panel receptacle provides quick access for testing 120V products. The rear panel
receptacle allows easy connection to any product rated 100-120V or 200-240V at up to 15 Amps, with
any plug configuration, using the appropriate adapter cord-set.
Front panel access to the internal meter circuit to measure leakage from surface-to-surface or
surface-to-ground as required by many Safety Standards.
Rear panel jacks provide access to the Body Circuit impedance to observe the wave shape of the
leakage current or to connect a second meter.
The ability to measure the leakage current of a product through the ground wire of the product's
power cord.
Understanding Leakage Current
A. What Is Leakage Current?
Leakage Current is the amount of current "filtered" to the grounding conductor by filtering components as
well as current that leaks through insulating materials. When a product is properly bonded to ground, the
leakage current will ideally follow this path to ground. However, if the product is not grounded or is
improperly grounded, a person contacting the product may become the path of least resistance. If this
occurs, the human body becomes the path for the leakage current with the result being dependent upon the
level of the current and the person in question.
B. How Is Leakage Current Measured?
To measure leakage current, the scenario described above must be created. The worst case exists when
the human body is the sole path for the leakage current. Therefore, when conducting this test the product is
energized with the grounding conductor disconnected, and all other possible ground paths isolated.
A meter representing the human body (Body Impedance Model) is then connected between the grounding
conductor of the product (or the enclosure) and the grounded conductor of the power system (neutral). The
grounded conductor is used rather than earth ground for several reasons including reliability/repeatability of
the test. (Distance from the ground point and other ground currents could affect the test). Some Standards
also require referencing both hot and neutral to simulate polarity reversal.
NOTE:
In some field testing situations, where the product is reliably connected to ground through
the building structure (i.e. mounted to a grounded pad, or connected to grounded water pipes,