One of these will do the job for a 30 amp receptacle.
http://www.amazon.com/Amp-600V-Bridge-Rectifier-Pack/dp/B001JSV678
Mount in a suitable box, or in the distribution panel itself if there is
room.
Jumper the + and - terminals.
Put the AC terminals in series with the shore ground.
Use appropriate 10 gauge wire and connectors.
Smear terminals with dielectric grease.
Done.
1.2V drop/isolation.
Steve Thomas
C&C27 MKIII
Port Stanley, ON
----- Original Message -----
From: "Leslie Paal via CnC-List" <cnc-list@cnc-list.com>
To: <cnc-list@cnc-list.com>
Cc: "Leslie Paal" <lpaalc...@yahoo.com>
Sent: Thursday, October 29, 2015 12:38
Subject: Re: Stus-List Galvanic isolator - Good idea?
in most cases the GIs have 4 diodes in them for 1.2V drop/isolation. (2
in series in each direction) Selecting components for a given amp rating
is not hard. But, selecting components and enclosure that can withstand
the environment is a bit of a challenge.
Leslie.
Phoenix C&C32 1983
--------------------------------------------
On Wed, 10/28/15, Don Wagner via CnC-List <cnc-list@cnc-list.com> wrote:
Subject: Re: Stus-List Galvanic isolator - Good idea?
To: "C&C List" <cnc-list@cnc-list.com>
Cc: "Don Wagner" <don.wag...@verizon.net>
Date: Wednesday, October 28, 2015, 1:55 PM
Josh
To answer your question about “What are the shaft
zincs protecting?”
Assuming you are in saltwater such as the Chesapeake,
Just a few things, including: the prop, the shaft, the
rudder post, the
keel bolts (especially if you have the C&C Smile), as
well as any other of
the usual underwater metals.
You should protect these items as the can’t be easily
inspected, but
failure can be a real disaster.
If you have a shaft isolator, you should install one
or more copper
jumpers between the engine coupling and the prop shaft
coupling.
Also Galvanic isolators
are suggested for
situations where you suspect the AC system at the marina or
nearby boats may be
compromised.
Note: Galvanic isolators
are a simple circuit
made up 2 big diodes wired in parallel but pointed in
opposite directions. Since
the diodes are not perfect they create about .6 volt DC
barriers to prevent the
corrosion currents needed for electrolysis.
A big capacitor is also
connected in
parallel with the diodes to allow AC current at low levels
and in case of diode
failure. All three components are mounted on a large heat
sink to keep the parts
cool and insure a longer life.
Don’t try building this
yourself, unless you can
design the proper size diodes and capacitors and heat sink the box
Just my
$.02
Don Wagner
C&C 41
CB
Der Baron
From: Josh Muckley
via CnC-List
Sent: Wednesday, October 28, 2015 12:48 PM
To: C&C
List
Cc: Josh Muckley
Subject: Re: Stus-List Galvanic isolator - Good
idea?
Since we're on topic. It seems that there
is a bit of differing
opinions on bonding the under water metals.
What are the shaft and prop zincs protecting?
If a shaft
coupling isolator were installed and no bonding wire
attached then the chance of
stray galvanic currents is eliminated. Right? What is
the risk
of this situation? I don't have bonding plates, bronze
through hulls, keel
coolers or anything else except the keel that is metal and
in contact with the
water.
I've considered possible corrosion effects
on internal engine
components and A/C components. Seems plausible but no one
ever talks about
it. Thoughts?
I've also considered the anode in the water
heater. Seems like
the most likely to experience stray galvanic currents and
the least likely to be
replaced or checked on any regular periodicity despite its
ease of access within
the boat.
I have 2 30 amp connections but use a y-adapter
so only 1 shore power
cord is required. I also built my own galvanic isolator
for ~$30 with
parts from mouser.com, I've just never
had the
urgent need to install it.
Josh Muckley
S/V Sea Hawk
1989 C&C 37+
Solomons, MD
<snip earlier part of conversation>
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