AC ground current leakage

[CharlieJ]

transmitterdan's #15:
The ABYC does not make "rules"; it creates accepted standards, most of which have become ANSI Standards and are generally accepted within the Americas and are being further integrated with the ISO Standards in the EU.

The E-11 Standard requirement for connecting safety ground to ship's ground once and only once aboard makes good technical and safety sense. To advise against this is doing a dis-service to CF members who may not have the technical knowledge to make a responsible decision on this subject.

[smac999]

Originally Posted by transmitterdan

The ABYC “rule” makes no sense. It’s better to “break” the stupid ABYC rule than kill people and boats in poorly designed marinas. Just my opinion.

When on internal ship’s power it makes sense.

So boat A has the dc to ac bond. And boat B does not.

Take an ac wire from say the ac panel to an outlet or hwt whatever.

Now rub that wire onto an engine block or through hull or a metal hull. Untill the hot wire is shorting to it. What happens?

Boat a
Dc ground Provides a return fault path back to ac source to clear fault current. Ac breaker trips. No harm done.

Boat b. Engine / through hull / metal hull goes hot 120v. No breaker will trip as there is no fault path back to source. Water goes 120v hot around boat. Swimmers near boat will die. Somebody walks into engine room and touches engine may die.

Why the bond was created.

[transmitterdan]

Yes, i know why the bond is there. But it is a very rare problem bordering on almost never happens. I have never seen it happen. It is a theoretical thing because many boats have black DC return wires and black AC hot wires. A stupid electrician (or owner) might mistake one for the other. The ABYC long ago preferred not to use black wire for DC negative but people still do it.

Swimmers in marinas have been killed because the shore ground is either missing or high resistance. Also, boats suffer damage from leakage current. All because of this bonding recommendation. I believe other countries don’t do this, only the US does it. I don’t think they do it in Europe and they have residual current devices mandated on boats.

Mains electricity cannot be made idiot proof until we force all marinas (or boats as in Europe) to install residual current devices. Even then there will be plenty of poorly maintained marinas and boats. And swimmers will still be drowning. And boats will still corrode and sink.

It’s about figuring out which protocol does the least harm. But ABYC isn’t interested in having the discussion as we have seen in this thread. So we should drop it now or start another thread where we can have the discussion.

[GordMay]

The National Electrical Code (NEC/NFPA 70) and ABYC now both have requirements for ground fault protection.


NEC Article 555 now requires that receptacles providing shore power must have GFP set at not more than 30 mA.

ABYC E–11.11.1 states:
“... An Equipment Leakage Circuit Interrupter (ELCI) shall be installed with or in addition to the main shore power disconnect circuit breaker(s) or at the additional overcurrent protection as required by E–11.10.2.8.3 whichever is closer to the shore power connection...”
ABYC E–13.3.5 states:
“... If installed in a head, galley, machinery space, or on a weather deck, the receptacle shall be protected by a Type A (nominal 5 milliamperes) Ground Fault Circuit Interrupter (GFCI)...”
ELCIs have a maximum trip current of 30 mA, as do Euro’ RCDs.
GFCIs have a maximum trip current of 6 mA.

[CharlieJ]

transmitter dan #18:

It’s about figuring out which protocol does the least harm. But ABYC isn’t interested in having the discussion as we have seen in this thread. So we should drop it now or start another thread where we can have the discussion.

What logic led you to this conclusion?

Your comment is absolutely invalid, false and does a discredit to the hundreds of volunteers who constantly review and discuss the Standards to ensure that they are technically correct and that they promote boating safety. After posting over 5,000 comments on this Forum, I would have expected that you would be better than this.

It is a theoretical thing because many boats have black DC return wires and black AC hot wires.

This has absolutely nothing to do with the AC > DC bond requirement.

Also, boats suffer damage from leakage current.

Stray current damage caused by AC is nearly impossible in the wild. It can happen but the leakage current required is very, very high.

Here is a thought: Contact the Technical Director, Brian Goodwin at 410-990-4460 x115 and ask to be put on the mailing list for Standards such as E-2, E-11, A-28 and any others where your expertise may help. You will receive all of the comments and discussions regarding the Standards you are interested in and you will be encouraged to participate in their review and revision. Then "you" become part of "they".

[CharlieJ]

...and, by the way, the AC > DC ground connection is required in Europe unless an ELCI is installed on the vessel.

[transmitterdan]

CharlieJ,

I appreciate your comments. I know you have contributed a lot to boating electrical safety. It’s true that the ABYC logic on some things is a bit opaque to those on the outside. I will take you up and ask to join their email group. I am a degreed EE with many years experience in power systems design of up to several millions of watts. And I truly love boating and hate to see swimmers die from preventable shock hazards.

I am a bit over sensitive to safety. It should never happen that a swimmer is drowned by shock from a boat. But it happens and the industry solution is to simply ban swimmers in the marinas.

It seems to be cheaper to put up “No Swimming” signs than fix the problem on shore where it is best solved. The boating/marina industry needs to change its approach to this issue in my opinion. We have the technology such that there is no need for another swimmer death or these threads where 100+mA of current flows in the shore ground and the boat owner cannot stop it. That’s an easily solvable problem. But as long as we connect shore mains safety ground to the water it will keep happening.

I apologize to you and again want to recognize your contribution to safety. It is appreciated.

[CharlieJ]

@transmitterdan:
You obviously hit a nerve so thank you, apology accepted and welcome aboard! I know you will have a lot to contribute to the process.

It seems to be cheaper to put up “No Swimming” signs than fix the problem on shore where it is best solved. The boating/marina industry needs to change its approach to this issue in my opinion.

Have you been following the modifications over the last three review cycles of NFPA 70 (NEC) Art. 555 and NFPA 303? If not, and if you have some interest, PM me and I can provide some excellent information.