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Troubleshooting tips: 1) In a single-phase circuit, if the value of L-N is high
the leakage current in the neutral line or the earth line will also be high. 2) In a
three-phase circuit with a neutral line, if the value of N-E is high the three-
phase load is either unbalanced or the neutral line is affected by harmonic
interference.
MEASURING VOLTAGE DROP
The CA10 can calculate and display a circuit's voltage drop in response to
application of a 12A, 15A or 20A dummy load. In all three cases, the voltage
drop displayed on-screen as a percentage is based on the True RMS value of
the drop on the circuit's phase (live) line.
To select the voltage drop test, press the FUNC button until Vd is highlighted.
Then, for 120V circuits, press the
or
button to select the 15A or 20A
test (see figure below) to match the rating (maximum load) of the circuit.
Alternatively, select the 12A test for a 15A or 20A circuit to avoid tripping the
breaker of a "preloaded" circuit (i.e., a circuit serving other loads during the
load test).
To begin, plug the free end of the test cable into the branch circuit's outlet that
is furthest from the breaker box (distribution panel). Press the TEST button
(Fig. 1, Callout 9) to initiate the test. The test result, a percentage, will appear
on the lower readout of the display.
The normal measurement result of the voltage drop test is a number less than
8%. If your result for the most distant outlet in the circuit is <8%, there is no
need to check any other outlet(s) of the circuit closer to the breaker box. If your
result is greater than 8%, repeat the test on the outlet that is next-closest to
the breaker box. Keep repeating the test until you get a normal measurement
result. A voltage drop of more than 8% is usually caused by loose connections,
poorly spliced conductors, or conductors that are too thin for the circuit's load.
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