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5
Voltage Drop Testing
The ST-1D checks the voltage drop of a receptacle under a full 15 ampere
load without interruption to equipment on the circuit. The voltage drop
LEDs, located on the left side of the instrument, will indicate a pass/fail con-
dition based on the maximum voltage drop for branch circuits recommend-
ed by the National Electrical Code for reasonable efficiency. (NEC article
210-19. FPN 4)
1. Insert the ST-1D into the receptacle
•
Green
confirms that a full 15 ampere load causes less than
a 5% voltage drop
•
Amber
indicates that the voltage drop in the circuit is greater than
5% under a full 15 ampere load
Line Voltage Testing
The St-1D checks line voltage of the receptacle to ensure that it is within
10% of the nominal line voltage. For the 120VAC version, #61-152, the
line voltage should be between 108 and 132 volts. For the 230VAC version,
#61-153, the line voltage should be between 207 and 253 volts.
1. Insert the ST-1D into the receptacle
•
Green
confirms that the line voltage is within 10%
•
Red
indicates that the line voltage is beyond the specified 10%
tolerance
NOTE: A failure of the line voltage test will force a failure of the voltage
drop test.
Electrical Measurements
In addition to pass fail/indication of key wiring and electrical test parame-
ters, the ST-1D will measure key electrical values such as line voltage, volt-
age drop under 15 and 20 ampere loads, ground-to-neutral voltage, esti-
mated load and ground impedance. These measurements are accessed
through a simple programming menu.
Unless a false ground condition exists, the ST-1D will show "L-n"- in the
LED display, located on the bottom of the instrument. This indicates that
the unit is calibrating itself prior to testing. After this calibration is per-
formed, the ST-1D automatically enters into the programming menu. The
LED display cycles between the numerical sequence of the test, and the
measurement every four seconds. Press and hold the display advance but-
ton for 1 second to move through the menu to the next test.
1. Insert the ST-1D into the receptacle
2. The LED display will show "L-n"- to indicate self-calibration of the unit
3. The LED display will show “1=” to indicate that the first measurement is
being taken.
4. The first measurement is tested and displayed
5. The LED display alternates between the numerical sequence of the test
and the measurement every four seconds
6. Press and hold the display advance button for one second to move to
the next test
The fifth measurement, estimated load, is the final test in the menu.
Pressing and holding the display advance button will move back to line
voltage, the first test in the menu.
Line Voltage Measurement
The line voltage test is indicated on the LED display by “1=”. After four
seconds the display cycles to the actual line voltage measurement. The
LED display alternates between “1=” and the line voltage measurement
every four seconds.
Voltage Drop Measurement - 15 Amp Load
The voltage drop test at 15 Amps is indicated on the LED display by “2=”.
This measurement is tested under a full 15 ampere load without interruption
to equipment on the circuit. The National Electrical Code recommends 5%
as the maximum voltage drop for branch circuits for reasonable efficiency.
(NEC article 210-19. FPN 4)
Voltage Drop Measurement - 20 Amp Load
The voltage drop test at 20 Amps is indicated on the LED display by “3=”.
This measurement is calculated from a 15 ampere load.
Ground-to-Neutral Voltage Measurement
The ground-to-neutral voltage test is indicated on the LED display by “4=”.
Ground-to-neutral voltage results from current flowing in the neutral con-
ductor from other equipment on the circuit. High ground-to-neutral voltage
indicates that the circuit may be loaded near its capacity or the neutral con-
ductor may be shared or carrying harmonic distortion. A reading of less
than 2 volts usually indicates a usable outlet. An excessive ground-to-neu-
tral voltage may result in inconsistent or intermittent equipment perfor-
mance. This is a peak reading, which will be reset by pressing the display
advance button, and cycling through the menu until the LED display shows
“4=” again.
