Hi:
OK, in short I think there are two questions here: 1) Connect the onboard AC safety ground to the onboard DC Ground point: Yes - always. There has been several articles over the years on people dying when swimming around a faulty boat w/o this connection. ABYC requires it. Some will complain that this can cause issues with stray current and galvanic issues, but bottom line: This bonding is a major safety issue, the other concerns can be addressed below. And more so, if something does go very very bad, and you do not have this on your boat can cause lots of problems for you. Here is an article of a local boy who died as a direct result of the boat not having this connection and a fault occurring: http://www.abycinc.org/lucas_ritz.pdf 2) Connecting of ships AC Safety Ground to Shore Safety Ground.: There are basically two ways to do this: 1) make the connection via your shore power cable - use of a galvanic Isolator can help reduce some of the stray current concerns here. And 2) use a true isolation transformer. In this case, the shore safety ground is only connected to the shield in the transformer, and then a new bonding point is established by connecting the ship safety ground and ship neutral onboard (and after the isolation transformer). This approach will remove almost all issues with stray currents. This is not really that complex of a topic, though some folks like to poke at #1 and cause confusion. Note also that the above might be modified some for non US boats (e.g. EU boats). I am just not sure the best practice for them and the AC system can be slightly different then the US system. (Beyond 120v/60hz..) Good luck! -al- From: [email protected] [mailto:[email protected]] On Behalf Of Emory Jones Sent: Wednesday, December 08, 2010 4:30 PM To: [email protected] Subject: Re: [Liveaboard] GALVANIC ISOLATOR Thanks to all who responded! There does not seem to a consensus in regard to the AC ground. Any other (additional) discussion would certainly help to educate me. I am concerned about an AC to DC connection however my fears may be ungrounded (sorry I couldn't resist). Thanks again for all the input. Emory Jones S/V Jacob Andrew Solomons, MD
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