Proper Grounding for AC and DC

[boatpoker]

Originally Posted by Maine Sail

ABYC still requires all on-board originating "sources", inverter, generator or isolation transformer to be grounded (green wire) to the ships DC grounding system. Neutral and ground are only connected at the source end..

As I read ABYC, E-11, if an inverter or generator are on board, they become the source rather than shore power, therefore neutral and ground would be bonded at source i.e. generator and or inverter

[boatpoker]

I've been involved in a number of lightning claims (all in fresh water) ahve have seen boats that met all the ABYC standards and one that had all the current geegaws from static disipator and ion disipator, dynaplates et al. Most that I have seen had significant hull damage from side flashes (remember fresh water hits are much different than salt).

I have come to the conclusion that regardless of any system on your boat, 60 million volts, travelling at about 90,000mph and hotter than the surface of the sun .... well, it's going wherever the hell it wants.

[s/v Jedi]

Originally Posted by boatpoker

I've been involved in a number of lightning claims (all in fresh water) ahve have seen boats that met all the ABYC standards and one that had all the current geegaws from static disipator and ion disipator, dynaplates et al. Most that I have seen had significant hull damage from side flashes (remember fresh water hits are much different than salt).

I have come to the conclusion that regardless of any system on your boat, 60 million volts, travelling at about 90,000mph and hotter than the surface of the sun .... well, it's going wherever the hell it wants.

For many it is the way to not understand it. But for many others, it is just a violent way of an electrical discharge which follows all laws of physics. Where ones sees nothing or just air, another sees a potential conductor after ionization. When something is discussed that not everybody who participates in the discussion understands, it gets messy with the voodoo and magic and what more.

Science has come a long way since the human kind believed that thunder and lightning was caused by an angry Thor. We can in fact create lightning ourselves which is done on a regular basis in laboratories to approve equipment incl. the lightning rods. That is where the 100% effective numbers come from, cold scientific method. I agree, boring, compared to voodoo.

ciao!
Nick.

[s/v Jedi]

Originally Posted by boatpoker

As I read ABYC, E-11, if an inverter or generator are on board, they become the source rather than shore power, therefore neutral and ground would be bonded at source i.e. generator and or inverter

Yes, unfortunately they do that. Remember that ABYC only makes recommendations and only for US yachts. Most other nations feel strongly different about that and do NOT endorse polarizing on-board AC sources, let alone connecting them to the DC system.

Many inverters allow you to change that neutral grounding behaviour (done by internal relais). And every genset allows you to remove the jumper that grounds the neutral.

On a sidenote, I'm starting to understand why US aluminium boats haveso many electrolysis problems... they make batteries out of them

cheers,
Nick.

[Maine Sail]

Originally Posted by boatpoker

As I read ABYC, E-11, if an inverter or generator are on board, they become the source rather than shore power, therefore neutral and ground would be bonded at source i.e. generator and or inverter

Exactly correct. Sorry if my wording was confusing. My point was that only at a "source", or more correctly inside the source, generator, inverter, isolation transformer are the green and white tied together. They are also obviously tied together at shore too as that is a "source". Once the green & white wires leave a source they are not again tied together on the boat. When wires leave an on-board "source" the green gets connected to ship DC ground to meet the current ABYC standard as does a shore power grounding conductor... White & green are only connected at a "source"..

[goboatingnow]

Originally Posted by Maine Sail

Exactly correct. Sorry if my wording was confusing. My point was that only at a "source", or more correctly inside the source, generator, inverter, isolation transformer are the green and white tied together. They are also obviously tied together at shore too as that is a "source". Once the green & white wires leave a source they are not again tied together on the boat. When wires leave an on-board "source" the green gets connected to ship DC ground to meet the current ABYC standard as does a shore power grounding conductor... White & green are only connected at a "source"..

Actually for on board isolated AC sources the stipulation that the dc negative and in effect ac neutral/earth are connected makes even less electrical sense.

Dave

[hpeer]

A practical question on this grounding topic.

Boat is a 44' STEEL cutter.

The PO had a Paneltronics 4401 series panel installed in 2006.

Diagram here: http://paneltronics.com/technical/Wi...eluxe/4401.pdf

Note that they have two DC buses:

1: DC Grounding Bus - this has 2 about #10AWG wires dissapearing into the wiring harness. I'll dive after this connection soon.

2: DC Negative Bus - this goes to the negative side of the battery.

They are NOT connected and have about 5 volts between them.

Clearly this is an engineered solution and there is some good reason for it. What?

[s/v Jedi]

Originally Posted by hpeer

Clearly this is an engineered solution and there is some good reason for it. What?

Isolating DC negative from ground is great and the standard for metal boats. It eliminates electrolysis.

The ground wires will attach to some underwater metal part.

ciao!
Nick.

[rtbates]

On our 25D with a diesel, years ago I separated the DC gnd from the AC ground because of an issue with stray currents and tripping my GFIs.. The ONLY place that our AC circuits connect to ground is at the SUPPLY PANEL on shore. No AC generation equip on board.

[hpeer]

Originally Posted by s/v Jedi

Isolating DC negative from ground is great and the standard for metal boats. It eliminates electrolysis.

The ground wires will attach to some underwater metal part.

ciao!
Nick.

Nick - thanks for answer.

1. I can understand isolating Battery negative from ground/hull. Good idea.
2. I can understand having some connection from the hull to the electrical panel so that you can test to assure you don't have an inadvertent ground connection.
3. I can appreciate that this panel is designed for fiberglass boats and not steel.

What I don't get is why to parallel each Bat neg bus with a DC ground bus of the same size and capacity for either FG or metal.

Why would they do that?

[Ian R]

by aussiegeoff.
AFAIK, unlike caravans, there's no Australian regulations for mains power on boats, and Australian Standards only seem to cover commercial power.

There are regulations on all boats,each state has it's own regs.
Mains power is not a definition that applies,any low voltage eg 110 or 240 volt from any source (generators etc)is regulated.12 volt is extra low voltage.
Here is some info from Queensland transport .http://www.msq.qld.gov.au/~/media/ba...s_licences.pdf

[Ike]

Australian and New Zealand National standards for recreational boats are found here. The document in Ian R's post is a little out of date.
:: National Marine Safety Committee ::: ::
Put your cursor over Standards And Publications, Select National Standards, Scroll down to Recreational Boat Standards.