RF ground bus shall be connected to the DC
ground, and must be directly connected to the
engine ground and through-hull ground plate
for the specific purpose of reducing RF noise
on board.” Herein lies the confusion. What is
being called for is a dedicated RF ground bus
that may be tied into the rest of the boat’s
grounding buses (AC and DC) and also at the
“engine negative terminal” as the ABYC
describes it. So the question becomes, is it iso-
lated from everything else or is it connected?
This is a case where a picture says a thou-
sand words. Use the illustration on page 126
as a guide for how these connections should be
made, and you will be compliant, not only
with ABYC E-11, but also with the NMEA
electronics installation standard as it applies to
grounding.
If your equipment is installed in accor-
dance with the ABYC recommendations as
shown in that illustration, and you still experi-
ence noise-related issues, then the solution is
an electronics grounding system that is com-
pletely isolated from the rest of the onboard
system. You will still be in compliance with
the ABYC standard, as long as the rest of the
components shown in the illustration are
wired as shown.
That said, I’ve rarely seen a situation where
the configuration in the illustration caused
any problems with equipment operation. In
my opinion, the difference between the NMEA
statements and the ABYC diagram is one of
semantics rather than a clear-cut difference.
The NMEA does, after all, reference ABYC E-11as the guide for equipment wiring within its
installation standards.Troubleshooting Redux
Before we move on to Part 2, in which we’ll
look at electronics installations, I’d like to
reemphasize what I feel is crucial to effective
electrical systems troubleshooting.
It’s important to look at your work and
your routines carefully, think about what you
do most frequently, and about what you could
do if you had access to a given piece of gear. If
you’re a professional marine technician, con-
sider how it might help your bottom line; if
you’re a boatowner, consider the money you’ll
spend and the time you’ll have to invest to
learn how to use a new device, and weigh
those against the limited usage to which you,
as the technician responsible for a single boat,
will probably put it. Go through a cost/benefit
analysis to determine which devices make the
most sense for you to purchase.
Whether you’re a professional or an ama-
teur, don’t immediately run out and buy every
instrument we’ve discussed in Part 1. By them-
selves, they won’t automatically make you a
better electrician or a smarter boatowner. But if
you follow some of my recommendations and
suggestions, and attain a clear understanding
of the capabilities and the applications of each
new instrument before you consider buying
the next one, you will have mastered new, use-
ful skills and elevated yourself to a higher level
of competency.128 electrical systems troubleshooting