I'll run the resistance test when I get back to the boat, but I don't see
that it is going to tell me anything since the leakage only occurs when a
load is first applied to the DC side of the power brick. Even at that, it
takes more than just applying a load since there is a load charging the
batteries even if the laptop is not turned on. I haven't been back to the
boat since I started this thread, but will get more info the next time I go
up.

thanks for all of your feedback.

John

"chuck" wrote in message
ink.net...
Reflects my sentiments also, Terry.

Depending on the nature of any leakage, it may show up with a simple
ohmmeter test. If the resistance between the ground prong on the plug and
either of the other terminals is anywhere in the vicinity of 20,000 ohms
(6 mA @ 120 v) that is the problem. Ideally, your ohmmeter should indicate
an open circuit. These devices use disk ceramic capacitors that frequently
develop troublesome leakage resistance.

Chuck

Terry Spragg wrote:
johnhh wrote:



All gfi protected circuit branches the same? If so, a laptop fault,
potentially dangerous should be investigated by a professional. Is your
laptop connected to external speakers, or other accessories, possibly
interconnected with equipment on a different phase of mains power?

Most laptops use only 2 wire plugs, so cannot have a current imbalance in
the cableset typically the cause of gfi tripping. You may have a bad gfi.
You may have a salty moist sweat stain on plug terminal, wire, grip, etc,
to some earthed part of the boat. Clean the plug end with a mild
detergent and dry thoroughly.

If yours has a 3 wire plug, it may have a marginal leakage path from a
hot terminal to the safety ground. This can be difficult to prove, as
the current is so small, and it trips so fast.

You could test with a 2 wire extension cord, to see if this stops the
tripping. It might not be safe to use it regularly without repairing the
cause. You might be best to use insulating gloves while doing this test.

It seems unlikely there is an electrical contact on the case of the
laptop that might be in contact with an earth or even your hand, but that
too would only indicate an internal leakage through the power supply or
charger, which could be lethal, if circumstances get right.

As to why it might cause tripping a gfi in some other part of the power
system, you got me there, buddy, unless one gfi is feeding the other, and
they are just taking turns at tripping;-)

I think startup current surges would not affect a gfic, first because as
far as I know, they are not designed to be overcurrent circuit breakers,
except insofar as safety imbalance current is concerned and second, no
laptop should draw so large a surge. If so, I would suspect a resistive
or reactive neutral or hot connection path. Do you have galvanic diode
blockers in your shoreside earth line connector path? Do you have a
wireless card in your laptop?

Are you, as did a friend of mine, amazingly still alive, using a 110 v
device in series with a 220 v flourescent ballast circuit? Stranger
things exist in truth than in fiction.

Very curious.

Terry K