Date: Mon, 27 Apr 2009 23:39:03 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Warning confirmed Re: gfci outlet buzzes with inverter
In-Reply-To: <49e15ddf.c5c2f10a.2fd1.ffffec08@mx.google.com>
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Unless the inverter is designed, rated, and UL/CSA listed for use in an RV
application it should not be hard wired to anything. The Vanagon is small
enough that anything can be plugged into the inverter. True RV inverters
have a neutral,(grounded) that is the same potential as the grounding plug.
Yes there is a difference between grounded, (normal current carrying wire)
and grounding, (only carries fault current). Just imagine some walking up to
your van in bare feet with some unknown potential there.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Beierl
Sent: Saturday, April 11, 2009 11:20 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Warning confirmed Re: gfci outlet buzzes with inverter
I just checked out my AC/Delco model 59-204, rated 400 W / 3.5 A
max. I used three instruments to measure -- a 10,000 ohms per volt
analog meter, a 10 megohm true-RMS digital, and an electrician's
neon/solenoid "buzzer."
The Delco has real three-terminal sockets, and the third terminal is
connected to the instrument case. There was miniscule leakage
current (few microamps) from either phase to the ground
terminal. Voltage through 10 megohms was about 25 RMS. So far so good.
Then I checked from each phase to the minus power terminal, which is
chassis ground on the vehicle. Wham.
RMS meter measured 116 vac between phases, 67 vac from either phase
to minus terminal.
Analog "RMS-indicating, average-reading" meter measured 105 phase to
phase, 105 phase to minus terminal.
"Buzzer" measured roughly 120 vac phase to phase, roughly 100 phase to
ground.
The buzzer draws about 25 milliamps at 120 vac, which is why
electricians use it.
Conclusion:
1) If either phase ("hot" or "neutral") is shorted to the vehicle
chassis, sparks will fly and the future of the inverter is in doubt.
2) Both phases carry dangerous voltages with respect to vehicle ground.
3) Neither phase is dangerous with respect to the inverter chassis,
*UNLESS* that chassis is connected to vehicle ground. However if a
plugged-in device has either hot or neutral leakage to ground
terminal, that leakage will be available at the inverter chassis with
respect to vehicle ground.
All inverters may not be like this; but at very least a number of
them are. Each of the four or five I've owned, from Xantrex and
others, has warnings about connecting neutral phase to battery supply
-- can't quote any just now b/c I've no idea where any of them are.
Wes, you can do a quick check if you have an ohmmeter -- if the
chassis and the socket ground pin are connected together, but neither
is connected to the minus supply terminal, your situation should be
as described above.
d
--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"