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

Here’s how to perform the GFCI test:

1 Plug the tester into the GFCI or GFCI-
serviced receptacle.

2 Press the “GFCI” button on the tester.

3 If the GFCI is working, it will trip, and
the instrument will display the trip rate in
mA just before it blinks out.

4 To display the trip time, simply reset the
GFCI. How much time is too much? The
nominal trip delay time for GFCI devices
is 0.025 second or 25 milliseconds (ms).

5 If your readings are not close to these
values, replace the GFCI receptacle.

To test GFPs, simply depress the side arrow
key on the face of the tester to the 30 mA set-
ting and perform the test as described above.
This is an extremely valuable capability
because it corresponds to the 30 mA trip rate
that is a requirement for whole-boat protec-
tion everywhere in the world except North
America. Such whole-boat protection consists
of a 30 mA rated GFP installed at the boat’s
main shore-power connection. Any current
leakage on the boat that gets to the 30 mA
level will turn off the power to the entire boat.
(I am lobbying at the standards development

testing ac and grounding systems 55

level for the United States to adopt this

requirement.) Typically, boats coming to the

United States from Europe, New Zealand, and

Australia are equipped with these devices, and

any U.S. boats shipped to those regions must

install them. Boats from Asia, on the other

hand, are often built specifically for the U.S.

market and are therefore wired to North

American standards.

Use Table 4-4 to help you troubleshoot

GFCI problems.

The following photos show the complete

test sequence of this very useful device.

Expected Possible Possible

Measurement Result Problem Causes Solutions

GFCI test GFCI trips within GFCI doesn’t GFCI may be installed Check wiring for proper

trip time. trip within improperly. installation in accordance

proper trip with manufacturer’s

time. instructions and NEC.

GFCI doesn’t GFCI may be defective. Check wiring and ground.

trip. Replace GFCI if necessary.

Source: Ideal Industries, Inc.

GFCI Troubleshooting Tips

TABLE

4-4

Circuit testing, similar to what you can do with a simple $5

LED tester. In this case, the SureTest indicates “no ground,”

a dangerous condition.

1