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Old 05-12-2011, 21:51   #46
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Re: Proper Grounding for AC and DC

The problem with RCDs in the USA is one of jurisdiction. ABYC standards stop at the shore power cord. The dock and marina standards (NFPA 303)are set by the National Fire Protection Association (NFPA) and they haven't accepted RCD's yet. And I agree, they should, because many of the problems with current in the water start on the dock.
ABYCs adoption of an ELCI is an effort to circumvent the lack of RCDs.
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Old 06-12-2011, 00:15   #47
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Re: Proper Grounding for AC and DC

The Santa Cruz harbor is getting new docks, complements of the Tsunami and FEMA, and one of the conditions of the grant is that all the docks be rewired to current standards. I asked one of the harbor commisioners whether that included ground fault monitors or trips, and he said he would get back to me with an answer--I'll report when he does.
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Old 06-12-2011, 03:14   #48
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Re: Proper Grounding for AC and DC

Quote:
Originally Posted by goboatingnow View Post
I have to say Nick , I think lightening bonding to dynaplates is a complete waste of time, the wire just gets exploded. And anyway it's yours aluminium.

Dave
Astra went down in 40 minutes after a lightning strike.

Post inspection showed 4 X 1-3 inch holes near the base of the mast.

I personally believe a $5 wire is cheap insurance if it works in providing a path to ground.

Also the myth that the tallest mast gets hit is a myth. Note the triple spreaders on Defiance in the background of pic 86.
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Old 06-12-2011, 04:46   #49
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Quote:
Originally Posted by Ex-Calif

Astra went down in 40 minutes after a lightning strike.

Post inspection showed 4 X 1-3 inch holes near the base of the mast.

I personally believe a $5 wire is cheap insurance if it works in providing a path to ground.

Also the myth that the tallest mast gets hit is a myth. Note the triple spreaders on Defiance in the background of pic 86.
Exactly. But the whole subject of lightning, people start gigling when you describe any system to deal with it, stating that it is just luck if it works etc.

But providing a controlled path to ground is old and proven technology. I don't understand why people choose to ignore it, or believe it doesn't work.

It is known how to create a controlled path to ground on boats and it works 100%.... if done right.

cheers,
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Old 06-12-2011, 07:27   #50
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Re: Proper Grounding for AC and DC

Quote:
But providing a controlled path to ground is old and proven technology. I don't understand why people choose to ignore it, or believe it doesn't work.
quite, but the lightening conductor on my church steeple, is 3/4 by 1/4"" solid copper bar, not a $5 dollar wire. unless of course the lightening that hits boats is different of course.

Dave
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Old 06-12-2011, 08:09   #51
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Quote:
Originally Posted by goboatingnow

quite, but the lightening conductor on my church steeple, is 3/4 by 1/4"" solid copper bar, not a $5 dollar wire. unless of course the lightening that hits boats is different of course.

Dave
This is actually good philosophical theory. The mast conducts electricity. It has a certain cross section. I add a wire to the steel keel that has the same cross section as the hollow aluminum mast. The mast is now bonded to the keel with the same current capacity as the mast. I have done no harm to the boat or mast. I have not increased the likelihood of a strike. It "may" work. I don't need proof it will. You apparently do. Don't bond your mast, I have no gun to your head.

The philosophy is about consequences. Don't believe in bonding. Consequence of being wrong? Lose your boat. Believe in bonding. Consequence of being wrong? Nothing.

Here is another one. Don't believe in a God. Consequence of being wrong? Eternal damnation in burning fire. Believe in God. No downside...
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Old 06-12-2011, 09:31   #52
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Re: Proper Grounding for AC and DC

Quote:
Originally Posted by goboatingnow View Post
quite, but the lightening conductor on my church steeple, is 3/4 by 1/4"" solid copper bar, not a $5 dollar wire. unless of course the lightening that hits boats is different of course.

Dave
Our own boat has been hit and I work on others that have too. We lost everything electronic but no wires were damaged except for some very small NEMA & network stuff. Also skipped right over all the fuses but I do often see this..

I have seen wire jacketing vaporized but not physically seen adequate bonding wires vaporized, yet. That said lightning hits are anything but the same on each boat. Some have hardly any wire damage and others have melted jackets all over the place. I have heard of a sintered bronze plate being blown up, not personally seen it though. I've also worked on boats that took direct hits with sintered bronze plates that were fine and were bonded to the lightning system.. Still a sintered plate would not be my choice. I've also seen boats where the hull was fractured through yet the bonding/lightning wiring was still in decent shape.

One member at our club was on-board during their strike and it blew the bilge cabin sole boards out of place. They suspect from the lightning hitting the bilge water. The mast and chain plate lightning wires were still intact but their carbon fiber spar cost a LOT if money to repair.

Lightning does odd things and I gave up trying to predict what it will do. I know if it wants my boat it will get it. The same night we were hit a Cal 22 was hit. There were 1100 other sailboats in the anchorage and our mast was far from the tallest. The Cal 22 was one of the shortest. The little Cal 22 had holes blown in her hull where the VHF wire was laying on it and it was taking on water and sinking, our hull was fine as was all of our lightning wires, jackets and all.

My neighbor behind me was hit four years ago and had just spent a bunch of money on a "lightning protection system" with the fuzzy bottle brush and all... I though after he was hit that I'd be fine being next to him as he clearly attracted it away from me... I was clearly wrong..

Lightning sucks and there's not a whole heck of a lot I've found you can do. After our hit I called a friend at a very large marine insurer. After a few days and database research, talks with his Florida team (lots of strikes there), investigation teams and a call to his actuarial team they said they have not seen any success or measurable performance differences with any of the lightning systems out there.

This was not because they have not looked. He would not disclose what they pay out in lightning claims but he said it was a shockingly large number and something that is in the forefront of their marine division as a targeted area for claim reductions. They just can't find a system that shows any measurable improvement over any other. He claimed they have had hits and paid claims on all of the various lightning systems they know of. He suggested that if any system showed even some tangible benefit they would likely offer a discount to have one installed. I decided to leave my system as it was because at least our boat did not sink..! Of course if I am hit again it just may sink, who knows, not me...

The worst part of our hit was that every piece of gear in the boat was brand new having just finished a 100% re-wire over the preceding winter. All gear was replaced with the identical stuff... It could have waited a few years untill my gear was getting older and obsolete at least!!!
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Old 06-12-2011, 10:04   #53
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Re: Proper Grounding for AC and DC

Quote:
Originally Posted by Ex-Calif View Post
This is actually good philosophical theory. The mast conducts electricity. It has a certain cross section. I add a wire to the steel keel that has the same cross section as the hollow aluminum mast. The mast is now bonded to the keel with the same current capacity as the mast. I have done no harm to the boat or mast. I have not increased the likelihood of a strike. It "may" work. I don't need proof it will. You apparently do. Don't bond your mast, I have no gun to your head.

The philosophy is about consequences. Don't believe in bonding. Consequence of being wrong? Lose your boat. Believe in bonding. Consequence of being wrong? Nothing.

Here is another one. Don't believe in a God. Consequence of being wrong? Eternal damnation in burning fire. Believe in God. No downside...
Sure sure, voodoo electrics, Ive read the theoretical papers on this and there's little or no agreement. Few manufacturers feel such binding is neccessary.

ANyway my comments re dynaplates was in connection with connecting them to AC protective earth, which I see as useless.

Dave
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Old 06-12-2011, 14:27   #54
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Re: Proper Grounding for AC and DC

On the subject of lightning, check out this youtube video. Just the sort of thing that would disturb a man's late-afternoon nap.

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Old 06-12-2011, 14:31   #55
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See, there we go again. Voodoo, nonsense etc. All that directed to systems that are marketed to prevent strikes, which has NOTHING to do with what I talk about (controlled path to ground). So now everybody can relax and do nothing to make the boat safer.

About 3/4" x 1/4" solid copper conductors for lightning: overkill. In many countries just a round 1/4" copper is used and works 100%.

yes, it's really voodoo that electricity would prefer a copper conductor over ionizing air or fiberglass hulls.

cheers,
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Old 06-12-2011, 16:31   #56
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Quote:
Originally Posted by s/v Jedi
See, there we go again. Voodoo, nonsense etc. All that directed to systems that are marketed to prevent strikes, which has NOTHING to do with what I talk about (controlled path to ground). So now everybody can relax and do nothing to make the boat safer.

About 3/4" x 1/4" solid copper conductors for lightning: overkill. In many countries just a round 1/4" copper is used and works 100%.

yes, it's really voodoo that electricity would prefer a copper conductor over ionizing air or fiberglass hulls.

cheers,
Nick.
Nick read the technical articles. It's not that simple

Dave
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Old 06-12-2011, 17:17   #57
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Re: Proper Grounding for AC and DC

This might ruin your day too...



This too:

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Old 06-12-2011, 17:39   #58
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Want saying that you shouldn't have a lightening path to ground. In my reading you need about 10mm2 and a plate in excess if 0.1 sqM, much bigger for freshwater. This is the minimum. The current code is inadequate. In reality if you have an external lead keel that would be better utilised. And there still is the distinct possibility of side flashes.

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Old 06-12-2011, 18:18   #59
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Re: Proper Grounding for AC and DC

Reading with interest. Regarding both situations, ie mains and DC grounding plus lightning mitigation, how do both of these apply to a ferrocement construction?
I imagine the hull would be less likely to be holed by a lightning strike than, say, glass, but it would still be very destructive, particularly to electronics.

I'm wondering how to go about wiring mains and DC on board. It currently has no mains wiring at all and no shore power connection but we intend to use a genset. AFAIK, unlike caravans, there's no Australian regulations for mains power on boats, and Australian Standards only seem to cover commercial power and I don't think DC systems even rate a mention. I'm going to dig a little deeper and see what I can find.

I'd considered using a tap to the armature as 'ground' but if there's any contact between it and the water, there can be electrolyitic issues as I understand it, which could conceivably disintegrate the armature (not good). I've considered tapping into it somewhere and running a 'ground' connection to the water via a zinc anode or two as 'insurance' (about the only kind you can get for ferro in Oz) as there is probably a DC path to the water from the armature via the engine and prop anyway, which could conceivably (conflicting opinions) have impacts on it that way or possibly on the prop depending what its made of.

Be interested to hear from anyone who has 'been there, done that' with ferros particularly.

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Old 06-12-2011, 19:06   #60
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Quote:
Originally Posted by goboatingnow

Nick read the technical articles. It's not that simple

Dave
Indeed, it's not simple to do it right. But it is 100% effective if done right and it is 100% known how to do it right.

I don't know which articles you mean; I wrote many here on CF on the subject too. But I do know that people are severely confusing simple bonding with wizardry involved with lightning prevention. I clearly remember the last time I tried to explain that in a thread here... it ended with people starting to blame boats with the upside down brushes in the mast for thunder and lightning in the anchorage.

cheers,
Nick.
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