Grounds

fallguy

fallguy

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So, a small debate came up. Do the start and house banks need to share a common ground?

@gonzo

How can chassis grounds in the house system be grounded if not?

pretty sure my surveyor said yes to the above; wondering how to interpret abyc e11.16 is all
 
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If the start and house banks have separate grounds, there will be a voltage difference between said grounds. That will be a source of electrolytic corrosion. Also, that would mean having two separate charging systems on the engine. Further, the charging system for the house banks would have to be electrically insulated from the engine. That means the alternator itself, mounting bolts, etc. would need insulators. Can you verify the ABYC section? E-11.6 if for AC
 
I had a typo e11.16, not e1.16; fixed the original post, thanks and sorry

I am agreeing with you, but the abyc language is odd. Uses, if, in the opening language..
 
I am not sure to what section of E-11.6 the surveyor is referring to. Is this only for the DC system or for AC too?
 
gonzo said:
I am not sure to what section of E-11.6 the surveyor is referring to. Is this only for the DC system or for AC too?
Click to expand...
E11.16 is dc grounds

here is a copy we can delete after you read it

"If a dc grounding system is used...". How does one interpret the if here?

C3B2672D-6C36-4854-AE3C-116F0EACAB14.png
 
The grounding system is the connection between the negative in the engine/battery and the rest of the electrical and electronic systems. Figure 19 shows some of the typical items, like bilge pumps. I think maybe a small boat with an pull start outboard would qualify as not having a grounding system.
 
gonzo said:
The grounding system is the connection between the negative in the engine/battery and the rest of the electrical and electronic systems. Figure 19 shows some of the typical items, like bilge pumps. I think maybe a small boat with an pull start outboard would qualify as not having a grounding system.
Click to expand...
Is the house required to be connected to the engine?
 
If the DC ground is connected to the common ground buss, then there is a connection to the engine.
 
I know, an older post; anyway;
The guy who used to work for ABYC "teaching the teachers" for the ABYC electrical class(s) and wrote the text on corrosion control has given his blessing on my boats electrical system.
The engine system, (alternator/starter/start batteries/gage panel/electric fuel pump, all live in their own little world completely isolated from the "house" system, and together with a "Drivesaver" any currant is isolated from the prop shaft.
The engine is not a "Grand Central Station" for the boats DC grounds.
An off-engine mounted auxiliary alternator with separate ground terminal interfaces with the house batteries.
All house DC grounds are connected to a main bus that connects to the house battery negatives.
No "stray" currants anywhere, no corrosion anywhere.
No bonding scheme, no electrical connections to any underwater metal.
 
It doesn't matter how many people do it incorrectly; there is still a proper method.

To suggest not bonding to underwater metals, for example, is wise, is an error of epic proportions for some vessels.

What happens to underwater props and shafts when the bonding line is broken in a twin engine boat? Potential in an electrolyte..rapid corrosion. Just within the last couple months, a Facebook forum member posted that his bonding wire came loose from one side of his boat and it will cost him thousands as everything was eaten.

There are reasons for requirements. It isn't to rebel against them.
 
"There are reasons for requirements. It isn't to rebel against them."

Re-read 11.16.1, the key word is "If", as in "If a DC grounding system is installed".
You might also note that many of the European sailboats leave the factory without a bonding system.
It's not a cut-and-dried issue, individual boats built of different materials, and using different underwater metals
have different requirements.
My boat, being cold-molded, with fairly simple AC/DC installations, and having all bronze fasteners/thru-hulls/seacocks/keel bolts/rudder shaft, has no need of bonding.
The only underwater metal not of bronze is the prop shaft, and it's of Monel, and it happily co-exists with the bronze prop with just a small zinc.
Many times connecting-up iron engines/aluminum tanks/stainless tanks/steel this-and-thats, along with stainless and bronze underwater metals has the effect of CREATEING a pea-soup of various potentials, and then the common "remedy" is to keep applying/connecting more zincs, which in some cases just makes things worse.
If one wishes or needs a bonding system to stop corrosion an impressed cathodic system should be used.
A primary use of bonding is to prevent electrocution from on-board AC, and that is a valid issue worthy of its own discussion.
 
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