Electrolysis Bonding Question

[Beausoleil]

I have a quick question and I don't have my texts handy:

When bonding thruhulls, is it advisable to use intermediate busbars when you've got a large boat? Say, near centerline located aft, mid and fore, - bond them each together to have a center bonding conductor, and then fan out from each to the nearest thruhull?

And what about tying it to the lightning bonding system? At a single point, or have them share the same center conductor?

[Alan Wheeler]

Good question on the lightning system. I would suggest keeping that seperate. At least you may have a slightly better odd of the lightning going straight to earth without jumping to other systems. Although in reality, I doubt that would be much protection.
For the bonding, you can simply run a cable and daisey chain each fitting together, or you can take a central point and "star" each run out to a fitting. It makes little difference in that point. But you MUST, take one single wire back from that Bussbar to the common earth point fitted to the engine block.

[Beausoleil]

Originally Posted by Alan Wheeler

For the bonding, you can simply run a cable and daisey chain each fitting together, or you can take a central point and "star" each run out to a fitting. It makes little difference in that point. But you MUST, take one single wire back from that Bussbar to the common earth point fitted to the engine block.

Since Beausoleil is a little long (about 58' overall), and has quite a few thruhulls (gotta rectify that one day!), I was thinking of three "stars" interconnected with a common conductor would keep wiring lengths to a manageable minimum. The original builder went a little nuts with thruhulls for three heads, engine and genset water intakes, bowthruster (jet drive) inlet and port/stdb ports. Let's just say we have quite a few.

The lightning bonding system will be a challenge - there's no direct access from inside the boat to the stanchion bases and the genoa tracks - they're mounted to the bulwarks port and starboard (genoa tracks on the caprail on top of the bulwark). I can probably bond the tracks to the external chainplates, and possibly in turn bond some of the stanchion bases to the track - but I think that would probably cause more trouble than solve. It may be better to let the stanchions "float" since they're within the cone of protection.

I'll read up some more this evening from the Calder and Wing books addressing all things electrical and finish up my diagrams so that I can post them here for critiquing.

Let's see. We'll have the DC grounding, AC grounding, lightning, bonding, RF... lot's of "insurance" wiring!

[GordMay]

Yes, a common bonding bus is a good idea, and you can connect the lightning ground to it at one point.
See ABYC Section E-11
Figures 18, 19, & 20 (begins page 47/49)
https://www.abyc.com/committees/.%5CE-11.pdf

and

ABYC Section E-4 ~ LIGHTNING PROTECTION
http://192.82.104.224/documents/standards/abyc/E-04.pdf

[Alan Wheeler]

Yes the three "Stars" is OK. Just don't connect anyone fitting twice. In other words, every single fitting back to the buss shall be it's own single path. The buss shall also be one single run back to the main engine common ground point.

[allene222]

Why are you bonding your through hulls? Do you think they will short out to AC hot? Or are you just bonding them because someone said to bond them without knowing why? If you are bonding them to protect them from electrolysis then you should realize they only need protection because they are bonded. There is so much myth out there that I decided to write up an article on bonding boat metals together. There are times when it is good to bond and times when it is not and knowing why will allow you to decide what to do. My personal opinion is not to bond through hulls and certainly don't bond them to the lightning protection unless you want the lightning to blow out all your through hulls. I took out some unbonded through hulls that had been in salt water for over 50 years and they were pristine. I replaced them just because of their age and the lack of backing blocks.

Bonding and Corrosion

I hope you find it useful.

Allen

[GordMay]

Originally Posted by allene222

... There is so much myth out there that I decided to write up an article on bonding boat metals together ...
Bonding and Corrosion
Allen

Greetings and welcome aboard the CF, Allen.

[gettinthere]

Allen

What do I do when the surveyor writes up unbonded thru hulls and the insurance company insists that be corrected?

[cal40john]

Originally Posted by gettinthere

Allen

What do I do when the surveyor writes up unbonded thru hulls and the insurance company insists that be corrected?

I don't think it's changed. Bonding is an option not a requirement of ABYC.

See post #10

http://www.cruisersforum.com/forums/...und-14288.html

John

[foggysail]

Allen-

I did take time to read your paper. There is a lot of stuff there, too much to respond/ask questions in one bite but I do have a couple of comments.

Your points about problems related to AC grounds are well made but I see reasons for my boat to have both the AC bonds and the DC bonded together. Note, this is my boat and I am not recommending anything to others. This subject matter has litigious potential.

But back to AC bonding. AC circuits have a grounded conductor which is permitted to carry current. There is also a bonding or grounding conductor that bonds the circuit to a common ground in a remote location such as a marina's electrical load center. No current is permitted to flow in the bonding topology other than during a fault condition.

DC circuits found on boats have engines grounded along with most of the propulsion metals. There is also bonding that is not meant to carry current but is connected to the grounded DC wiring. It is nearly impossible as I see it to separate an AC bonding connection from a DC ground connection unless one fails to tie the AC bonding connection to that of the boat's grounded connection which will create serious safety issues.

Yes, there will be little resistance/impedance between the AC ground and the AC bond but again, the topology for separating bonding and grounding presented in the National Electric Code should isolate current flow in bonding (grounding) conductors.

Lightning! So many things happen with lightning that it is difficult to measure. There are things that are well understood. For example, the current in a lightning bolt can be thousands of amperes occurring in microseconds to milliseconds. DC resistance models do not apply. Wiring inductance can present a very large reactance because of the frequency composition of the lightning waveform (see Fourier analysis). Reactance is similar to resistance found in DC circuits. Very large voltage drops will occur during these phenomena. There could be arcing jumping to unbelievable places during the lightning bolt.

Even well grounded lightning protection circuits guarantee nothing.

Enough for one bite---

Foggy

[GordMay]

Originally Posted by allene222

Why are you bonding your through hulls? ...
... My personal opinion is not to bond through hulls and certainly don't bond them to the lightning protection unless you want the lightning to blow out all your through hulls...

Thanks for sharing your thought provoking opinions on bonding.

Your definition of grounding isn’t really responsive to it’s electrical meaning, nor intention; because it ignores the electrical connection.

Originally Posted by allene222 in Bonding and Corrosion

Definition: Bonding noun 1: fastening firmly together (syn: soldering)

I’d propose a more accurate definition, thus:
“Electrical bonding is the practice of intentionally connecting all metallic non-current carrying items together, to form a low-impedance electrically conductive path, so that they are at the same potential (i.e., voltage).”

Many experts, like yourself*, don't recommend the bonding of electrically isolated metal thru-hulls and seacocks.

* “... The simple conclusion is to not bond anything together except for safety reasons and try to find other ways to make the boat safe, like removing all the AC wiring...”

However, I’d direct your attention to a few interesting and informative articles discussing the life safety implications of electrical bonding.

➥ http://www.qualitymarineservices.net...or%20sheet.pdf

➥ http://www.qualitymarineservices.net...Connection.pdf

➥ Grounding And Bonding In Boats And Marinas A Vital Link To Safety

The current industry standards define the grounding and bonding requirements that are essential for personal safety and to prevent fires. Deviating from these standards places personnel at increased risk in the marine environment.

Even when the standards are followed to the letter of the law, there are effective strategies* to prevent or reduce the impact of electrically induced corrosion.

* To prevent bonding-related electrochemical corrosion, the bonding system must be connected to one or more sacrificial zinc anodes, which, being less noble than any associated metals, are sacrificed in preference to the fittings and gear you want to protect. Zincs must be checked periodically, and replaced in timely fashion.

If your boat is gasoline-powered, the American Boat and Yacht Council (ABYC) says that a metal fuel tank(s) and fuel-fill fittings must be bonded.

With diesel engines, bonding is optional.

The ABYC doesn’t require individual through-hull fittings to be joined to the bonding system, if they are electrically isolated.

I don’t know how you achieve isolation of a metallic through-hull (seacock), sitting in contact with water (sea and bilge), and connected by hoses (often) full of water.

I don't think very many cruising boats forgo AC shore power systems. Nor do you, when your battery charger is connected.

[foggysail]

Well Gord--

There is no need for me to take a "second bite." Good job!

Foggy

[allene222]

Originally Posted by foggysail

Allen-

I did take time to read your paper. There is a lot of stuff there, too much to respond/ask questions in one bite but I do have a couple of comments.

Your points about problems related to AC grounds are well made but I see reasons for my boat to have both the AC bonds and the DC bonded together. Note, this is my boat and I am not recommending anything to others. This subject matter has litigious potential.

But back to AC bonding. AC circuits have a grounded conductor which is permitted to carry current. There is also a bonding or grounding conductor that bonds the circuit to a common ground in a remote location such as a marina's electrical load center. No current is permitted to flow in the bonding topology other than during a fault condition.

DC circuits found on boats have engines grounded along with most of the propulsion metals. There is also bonding that is not meant to carry current but is connected to the grounded DC wiring. It is nearly impossible as I see it to separate an AC bonding connection from a DC ground connection unless one fails to tie the AC bonding connection to that of the boat's grounded connection which will create serious safety issues.

Yes, there will be little resistance/impedance between the AC ground and the AC bond but again, the topology for separating bonding and grounding presented in the National Electric Code should isolate current flow in bonding (grounding) conductors.



Enough for one bite---

Foggy

You absolutely do not want the marina AC ground and the boat DC ground connected for small currents. Just a little terminology first. The AC 3 wires are Hot, Neutral, and Ground. There are two ways to isolate your AC and DC grounds and still have them safe. Actually, I would argue there are three ways. My preferred way is to have no AC system on the boat. Then they are isolated. Assuming that is not an option, your best choice is expensive, an isolation transformer. This completely isolates your boat from the dock ground. You then connect your boat AC ground to the isolation transformer and that creates your safety ground. Perfectly safe but no connection to the marina AC ground. The more economical choice is a galvanic isolator. This device connects the marina AC ground and the boat AC ground together but with a couple of diodes so that you need to get over 1.2 volts before current will flow. That is low enough to be safe but high enough to stop the galvanic corrosion. If you don't do one of these three things you are putting your boat and all the boats in the marina at risk. That is why they make these things to isolate the grounds afterall.

Allen

[allene222]

Originally Posted by GordMay

Thanks for sharing your thought provoking opinions on bonding.

Your definition of grounding isn’t really responsive to it’s electrical meaning, nor intention; because it ignores the electrical connection.


I’d propose a more accurate definition, thus:
“Electrical bonding is the practice of intentionally connecting all metallic non-current carrying items together, to form a low-impedance electrically conductive path, so that they are at the same potential (i.e., voltage).”

Many experts, like yourself*, don't recommend the bonding of electrically isolated metal thru-hulls and seacocks.

* “... The simple conclusion is to not bond anything together except for safety reasons and try to find other ways to make the boat safe, like removing all the AC wiring...”

However, I’d direct your attention to a few interesting and informative articles discussing the life safety implications of electrical bonding.

➥ http://www.qualitymarineservices.net...or%20sheet.pdf

➥ http://www.qualitymarineservices.net...Connection.pdf

➥ Grounding And Bonding In Boats And Marinas A Vital Link To Safety

The current industry standards define the grounding and bonding requirements that are essential for personal safety and to prevent fires. Deviating from these standards places personnel at increased risk in the marine environment.

Even when the standards are followed to the letter of the law, there are effective strategies* to prevent or reduce the impact of electrically induced corrosion.

* To prevent bonding-related electrochemical corrosion, the bonding system must be connected to one or more sacrificial zinc anodes, which, being less noble than any associated metals, are sacrificed in preference to the fittings and gear you want to protect. Zincs must be checked periodically, and replaced in timely fashion.

If your boat is gasoline-powered, the American Boat and Yacht Council (ABYC) says that a metal fuel tank(s) and fuel-fill fittings must be bonded.

With diesel engines, bonding is optional.

The ABYC doesn’t require individual through-hull fittings to be joined to the bonding system, if they are electrically isolated.

I don’t know how you achieve isolation of a metallic through-hull (seacock), sitting in contact with water (sea and bilge), and connected by hoses (often) full of water.

I don't think very many cruising boats forgo AC shore power systems. Nor do you, when your battery charger is connected.

I edited my reply but the system ate my edits so here is an edited version.
---------------------------------

You absolutely do not want the marina AC ground and the boat DC ground connected for small currents. Just a little terminology first. The AC 3 wires are Hot, Neutral, and Ground. There are two ways to isolate your AC and DC grounds and still have them safe. Actually, I would argue there are three ways. My preferred way is to have no AC system on the boat. Then they are isolated. Assuming that is not an option, your best choice is expensive, an isolation transformer. This completely isolates your boat from the dock ground. You then connect your boat AC ground to the isolation transformer and that creates your safety ground. Perfectly safe but no connection to the marina AC ground. The more economical choice is a galvanic isolator. This device connects the marina AC ground and the boat AC ground together but with a couple of diodes so that you need to get over 1.2 volts before current will flow. That is low enough to be safe but high enough to stop the galvanic corrosion. If you don't use one of these three methods, you are putting your boat and all the boats in the marina at risk. That is why they make these things to isolate the grounds afterall.

Clearly if you do bond you need to have zincs electrically connected to the circuit. I mention that in the article regarding your prop but I assumed it was common knowledge and did not make a big deal about it. Assuming the shaft is grounded to the engine, that would protect anything else that is bonded. But bonding and protecting with zinc isn't free both in terms of the zincs but also the process eats wood and can eat the paint off the area around the through hulls as well. As I said, there are things that must be bonded for mechanical or safety reasons and for those you must protect them with zinc or equivalent. I will update the article to make this clear, thanks for pointing it out.

In terms of the definition, I didn't make it up, I just picked it from the various dictionary definitions. I thought it was better than the one about two guys bonding on a fishing trip. Soldering is a method of making an electrical connection so to me it meant this definition was talking about electrical connections. (but don't solder stuff on a boat)

Allen

[allene222]

Originally Posted by GordMay

Thanks for sharing your thought provoking opinions on bonding.

Your definition of grounding isn’t really responsive to it’s electrical meaning, nor intention; because it ignores the electrical connection.


I’d propose a more accurate definition, thus:
“Electrical bonding is the practice of intentionally connecting all metallic non-current carrying items together, to form a low-impedance electrically conductive path, so that they are at the same potential (i.e., voltage).”

Many experts, like yourself*, don't recommend the bonding of electrically isolated metal thru-hulls and seacocks.

* “... The simple conclusion is to not bond anything together except for safety reasons and try to find other ways to make the boat safe, like removing all the AC wiring...”

However, I’d direct your attention to a few interesting and informative articles discussing the life safety implications of electrical bonding.

➥ http://www.qualitymarineservices.net...or%20sheet.pdf

➥ http://www.qualitymarineservices.net...Connection.pdf

➥ Grounding And Bonding In Boats And Marinas A Vital Link To Safety

The current industry standards define the grounding and bonding requirements that are essential for personal safety and to prevent fires. Deviating from these standards places personnel at increased risk in the marine environment.

Even when the standards are followed to the letter of the law, there are effective strategies* to prevent or reduce the impact of electrically induced corrosion.

* To prevent bonding-related electrochemical corrosion, the bonding system must be connected to one or more sacrificial zinc anodes, which, being less noble than any associated metals, are sacrificed in preference to the fittings and gear you want to protect. Zincs must be checked periodically, and replaced in timely fashion.

If your boat is gasoline-powered, the American Boat and Yacht Council (ABYC) says that a metal fuel tank(s) and fuel-fill fittings must be bonded.

With diesel engines, bonding is optional.

The ABYC doesn’t require individual through-hull fittings to be joined to the bonding system, if they are electrically isolated.

I don’t know how you achieve isolation of a metallic through-hull (seacock), sitting in contact with water (sea and bilge), and connected by hoses (often) full of water.

I don't think very many cruising boats forgo AC shore power systems. Nor do you, when your battery charger is connected.

I just want to emphasize that when I said

"* “... The simple conclusion is to not bond anything together except for safety reasons and try to find other ways to make the boat safe, like removing all the AC wiring...”"

I am saying you do want to bond for safety reasons and go on at length in the article about the importance of doing this. I don't think boats should have AC wiring in them because I don't think it is safe but others might differ. I take safety seriously. Please don't miss the point.

Allen