AC DC common ground

[s/v Jedi]

Originally Posted by team karst

Ok. Floating scheme. Safer and unusual. It is the best for small designs. Although navy ships also do it. Its a good idea to monitor it for accidental grounding.

I recommend to still install all ground conductors to outlets etc. so that when one of the power carrying conductors develop a short to case ground you get a “grounded neutral” like a conventional system. As soon as a second short from the other conductor would develop, the breaker triggers.

The monitoring and alarms are used to prevent loss of power. Where normally, for a grounded neutral, a breaker triggers when a phase to case ground short develops, with loss of power as the result, now you can keep power and get an alarm. Very important for hospitals, fishing vessels, navy etc.

[Bowdrie]

Perhaps this is not essentially germane to the discussion, but to address some context.
The ABYC dates from 1954, when the vast majority of boats were still of wooden construction and in sheer numbers the production was quite low.
In those days the entire electrical system of, say a 30'>40' boat might consist of some nav lights, a few cabin lights, a bilge pump, and if the owner was financially able, perhaps a depth sounder and some sort of radio.
We also need to remember that almost without exception all of the underwater metals and much of the interior metals were of high nobility on the galvanic scale, ie. bronze/copper/Monel.
Having an AC system on board was quite rare except for a few outlets and, (maybe,) a battery charger, and many boats just used an extension cord brought in thru a portlight from the dock to charge the batteries.
With rudimentary systems and little electrical activity on board there was no need for complicated grounding/bonding schemes, and all the underwater metals existed quite comfortably with each other, (being all the same,)
As electrical systems proliferated, it was inevitable that ground-loops/radio grounds/reverse polarity, and corrosion issues started popping up.
Then the "bright idea" of bonding all the underwater metals, together with the internal metal tanks/devices would solve everything, WRONG.
What happened next was the mysterious signs of de-lignification of the wood around the seacocks and other hull penetrations.
The answer from the "experts", was to add zincs, and more zincs, WRONG again.
The addition of zinc only acerbated the destruction of the wood and OVER PROTECTED the bronze which if left alone DOES NOT need any protection.
Then as non-copper-based alloys started being used underwater on a larger scale, again the use of zincs increased, (they needed anodes to protect the inferior metals).
Fast forward to widespread AC use and people getting shocked.
The answer, connect the AC grounds to the DC ground, (engine>shaft>water).
But that wasn't enough, what if someone touched a seacock?
The answer, bring back the bonding, connect everything to the water.
Then there is the issue of ESD, which took years to even recognize, (it's much more common in fresh water).
So, now we have the means to prevent onboard shock hazard and "in water" shock hazard.
It's the RCD/GFCI devices, as well as isolation transformers, and used properly not only can they eliminate the AC ground to DC ground connection, but the bonding scheme and the galvanic isolator become superfluous, and with it the episodes of stray currant corrosion.
At that point individual anodes can be used to protect ONLY what is necessary, (bronze prop on stainless shaft is an example).
Yes, the ABYC is a good org, but they are hidebound and behind the curve on some issues.

[boatpoker]

Originally Posted by Bowdrie

Perhaps this is not essentially germane to the discussion, but to address some context.
The ABYC dates from 1954, when the vast majority of boats were still of wooden construction and in sheer numbers the production was quite low.
In those days the entire electrical system of, say a 30'>40' boat might consist of some nav lights, a few cabin lights, a bilge pump, and if the owner was financially able, perhaps a depth sounder and some sort of radio.
We also need to remember that almost without exception all of the underwater metals and much of the interior metals were of high nobility on the galvanic scale, ie. bronze/copper/Monel.
Having an AC system on board was quite rare except for a few outlets and, (maybe,) a battery charger, and many boats just used an extension cord brought in thru a portlight from the dock to charge the batteries.
With rudimentary systems and little electrical activity on board there was no need for complicated grounding/bonding schemes, and all the underwater metals existed quite comfortably with each other, (being all the same,)
As electrical systems proliferated, it was inevitable that ground-loops/radio grounds/reverse polarity, and corrosion issues started popping up.
Then the "bright idea" of bonding all the underwater metals, together with the internal metal tanks/devices would solve everything, WRONG.
What happened next was the mysterious signs of de-lignification of the wood around the seacocks and other hull penetrations.
The answer from the "experts", was to add zincs, and more zincs, WRONG again.
The addition of zinc only acerbated the destruction of the wood and OVER PROTECTED the bronze which if left alone DOES NOT need any protection.
Then as non-copper-based alloys started being used underwater on a larger scale, again the use of zincs increased, (they needed anodes to protect the inferior metals).
Fast forward to widespread AC use and people getting shocked.
The answer, connect the AC grounds to the DC ground, (engine>shaft>water).
But that wasn't enough, what if someone touched a seacock?
The answer, bring back the bonding, connect everything to the water.
Then there is the issue of ESD, which took years to even recognize, (it's much more common in fresh water).
So, now we have the means to prevent onboard shock hazard and "in water" shock hazard.
It's the RCD/GFCI devices, as well as isolation transformers, and used properly not only can they eliminate the AC ground to DC ground connection, but the bonding scheme and the galvanic isolator become superfluous, and with it the episodes of stray currant corrosion.
At that point individual anodes can be used to protect ONLY what is necessary, (bronze prop on stainless shaft is an example).
Yes, the ABYC is a good org, but they are hidebound and behind the curve on some issues.

A couple of additional historical notes ..
1.There is not a single recorded case of ESD in salt water.
2. Kevin Ritz, the discoverer of ESD who along with retired nuc sub commander Dave Rifkin was hired by USCG and BoatUS to study the issue are both firm believers in AC/DC bonding.

[s/v Jedi]

Originally Posted by boatpoker

A couple of additional historical notes ..
1.There is not a single recorded case of ESD in salt water.
2. Kevin Ritz, the discoverer of ESD who along with retired nuc sub commander Dave Rifkin was hired by USCG and BoatUS to study the issue are both firm believers in AC/DC bonding.

Sorry, but this is wrong. First, ESD should be called Electric Shock Drowning, because ESD is something entirely different. Second, getting electrocuted in water was discovered very shortly after the discovery of electricity. Kevin Ritz became known as an advocate to prevent these deaths after his son died during swimming in their marina.

According to Wikipedia:

For some reason, the accident type is prevalent only in the USA.

and this is for the simple reason that the USA is about the only place that allows electrical installations near the water without the use of RCD safeties. This is what kills Americans, not a missing bonding jumper between AC and DC systems aboard boats.

All this anecdotal evidence and name dropping has no merit when science simply points to the reason for the danger and that is a return path via ground. Even all of the ABYC, Kevin Ritz and Dave Rifkin feature drawings showing this return path via ground as the killer.

I believe they also call for an RCD (they ramble on about inventing ELCI because they didn’t get that RCD was invented 30 years prior and in use worldwide for decennia) as being the final solution, yet the US still does not have this.

Instead, they keep piling onto a heap of BS with methods to fight symptoms instead of fixing the cause. A very silly and debatable path…

Luckily boats can just be done with all that BS and install an isolation transformer, WHICH BREAKS THE RETURN PATH VIA GROUND and thus eliminates all risks.

I will attach my diagram once again: do this and your boat is safe, your crew is safe and anyone in the water around you is safe. All other options are inferior and will cost you dearly in repairs as described in previous posts.

[boatpoker]

Originally Posted by s/v Jedi

Sorry, but this is wrong. First, ESD should be called Electric Shock Drowning, because ESD is something entirely different. Second, getting electrocuted in water was discovered very shortly after the discovery of electricity. Kevin Ritz became known as an advocate to prevent these deaths after his son died during swimming in their marina.

Of course electricity and water causing deaths has been well known for a long time.
ESD (electric shock drowing) as related to boats was an unknown cousin until Kevin fought the USCG and the coroners office to prove his son drowned due to paralysis caused by electricity leaking from a boat.

[s/v Jedi]

Originally Posted by boatpoker

Of course electricity and water causing deaths has been well known for a long time.
ESD (electric shock drowing) as related to boats was an unknown cousin until Kevin fought the USCG and the coroners office to prove his son drowned due to paralysis caused by electricity leaking from a boat.

Indeed, and after all that fighting and all the deaths, still no RCD safety required near the water. Well, for boats they now do, but it must be done shore side just like in the rest of the 1st world.

Isn’t that the NEC who is at fault?

[Bowdrie]

Originally Posted by boatpoker

A couple of additional historical notes ..
1.There is not a single recorded case of ESD in salt water.
2. Kevin Ritz, the discoverer of ESD who along with retired nuc sub commander Dave Rifkin was hired by USCG and BoatUS to study the issue are both firm believers in AC/DC bonding.

For #1, true, but "not recorded" does not mean "never having happened".
For #2, I do not know Dave Rifkin, and as such have no knowledge of his opinions on that.
I do know that Kevin Ritz used to work for ABYC, and he does believe that (paraphrasing,) "the vast majority of boats should have the AC/DC bonding installed".
I might also add that Kevin and I have been personal friends for going on 25 years, (I was on the dock when his son died of ESD,) and we have discussed the topics of ESD and bonding/corrosion on numerous occasions, and most likely in greater depth than what is presented in the classes, (if only for the sheer number of hours spent on the subjects,) and marine electrical issues in general.
My wiring scheme is safe, both for those aboard and for swimmers.

Edit, Sorry S/V Jedi, I "name dropped", but I wanted Boatpoker to know that I have some knowledge that has come in a most direct manner, so to speak.

[s/v Jedi]

Originally Posted by Bowdrie

For #1, true, but "not recorded" does not mean "never having happened".
For #2, I do not know Dave Rifkin, and as such have no knowledge of his opinions on that.
I do know that Kevin Ritz used to work for ABYC, and he does believe that (paraphrasing,) "the vast majority of boats should have the AC/DC bonding installed".
I might also add that Kevin and I have been personal friends for going on 25 years, (I was on the dock when his son died of ESD,) and we have discussed the topics of ESD and bonding/corrosion on numerous occasions, and most likely in greater depth than what is presented in the classes, (if only for the sheer number of hours spent on the subjects,) and marine electrical issues in general.
My wiring scheme is safe, both for those aboard and for swimmers.

Edit, Sorry S/V Jedi, I "name dropped", but I wanted Boatpoker to know that I have some knowledge that has come in a most direct manner, so to speak.

Completely understandable. I would like to see your wiring scheme.

[Bowdrie]

As relates to Zincs.
Maybe some of you guys follow "Sailing Atticus" on YouTube, it seems that they have an issue with the prop zinc wasting away quite prematurely, and he doesn't know what to make of it.
Anyway, if you fast forward to ~15:30 you'll see/hear about it.
I do know from following them that the boat has miles of wiring running everywhere, (and I'll bet the underwater metals are bonded).

https://www.youtube.com/watch?v=vI3e3NQ9fqw

[boatpoker]

Originally Posted by Bowdrie

As relates to Zincs.
Maybe some of you guys follow "Sailing Atticus" on YouTube, it seems that they have an issue with the prop zinc wasting away quite prematurely

Hard to say if it's "pre-mature" without any time reference.

PS. 90% of the boats we've surveyed (Canada & US) were not bonded.
I've only ever seen 4 boats that met all ABYC Standards and three of those were home built.

[Bowdrie]

Originally Posted by boatpoker

Hard to say if it's "pre-mature" without any time reference.

Ok, perhaps it's just a "thing" with the waters they've been sailing in.
Going back on the timelines of the vids it seems that they started off with the new prop and zinc ~7>8 months ago.
Those with experience in sailing those waters would certainly have more knowledge than I, (always having been on the US West coast).
It just seemed to me that having a zinc completely waste away in just a few months might perhaps point to some galvanic problem.

[boatpoker]

Originally Posted by Bowdrie

Ok, perhaps it's just a "thing" with the waters they've been sailing in.
Going back on the timelines of the vids it seems that they started off with the new prop and zinc ~7>8 months ago.
Those with experience in sailing those waters would certainly have more knowledge than I, (always having been on the US West coast).
It just seemed to me that having a zinc completely waste away in just a few months might perhaps point to some galvanic problem.

7-8 months seems reasonable for a zinc anode in salt water.
If it was stray current I think he'd have a lot more to worry
about than a zinc anode.

[Bowdrie]

Originally Posted by boatpoker

If it was stray current I think he'd have a lot more to worry
about than a zinc anode.

[pdqsailor]

Originally Posted by s/v Jedi

I recommend to still install all ground conductors to outlets etc. so that when one of the power carrying conductors develop a short to case ground you get a “grounded neutral” like a conventional system. As soon as a second short from the other conductor would develop, the breaker triggers.

The monitoring and alarms are used to prevent loss of power. Where normally, for a grounded neutral, a breaker triggers when a phase to case ground short develops, with loss of power as the result, now you can keep power and get an alarm. Very important for hospitals, fishing vessels, navy etc.

The Hammond isolation transformer I have has no input for ground - just line and neutral.. The question now is do I maintain the ground connection to the shore power ground from the ships wiring or go with a floating ground and GFCI protection only on the boat - which I am fine with BTW...

[goboatingnow]

Originally Posted by s/v Jedi

Because they serve no purpose with an isolation transformer. They should be in the dock pedestal, so that the shore power cord, which often hangs in the water, is protected.



Is it mandatory in shore power pedestals?



Anyway, my reference diagram is good as it is for ISO compliance.

Rcbo are mandatory inbtbd marina pillar

Very good in the input circuit to the transformer and very useful in the output circuit