Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

47

Checking for Polarity

One of the most common errors in AC wiring
is improper connection of the hot, neutral, or
ground wire at receptacles, which can be an
elusive problem. According to ABYC Stan-
dard E-11, most 120 V wired boats are
required to have a reverse-polarity indicator at
the main AC panelboard. However, the panel
indicator only monitors from the shore-power
pedestal to the panel; receptacles supplied
from the panel are not monitored by the indi-
cator. If they have been mistakenly miswired,
the panel indicator won’t pick it up, creating a
potentially dangerous situation at that recepta-
cle. By using the SureTest at every receptacle

testing ac and grounding systems

on the boat, you can easily check the polarity

and determine if you have to take action.

In this application, the SureTest replicates

the functions of a $5 circuit tester that you

probably already own. Don’t worry; this instru-

ment is capable of much more sophisticated

and useful testing, but these basic tests are

important, so we’ll review them first.

Here are the basics for testing polarity:

1 Plug the SureTest into an active receptacle.

2 The tester’s screen display should immedi-

ately light up.

3 The unit will progress from its opening

screen to a display of three green LEDs

indicating hot, ground, and neutral.

4 If all three LEDs are lit, it’s a firm indica-

tion that polarity is correct—in other

words, hot and neutral have not been

reversed.

5 Other LED combinations indicate various

AC wiring problems—an open-circuited

(not connected) hot or neutral, no-

ground situations, and false grounds.

The SureTest 61-164 circuit analyzer.
Wiring Condition

Correct Wiring

No Ground

Polarity Reversal

Open/Hot Neutral

False Ground

Display Indication

H G N

Legend On Off Flashing

F

The SureTest indicates different AC wiring problems by displaying vari-

ous combinations of its three LEDs.