Burned ground wire on inverter

[transmitterdan]

Originally Posted by roland stockham

I have never understood why ABYC do this. European regs say the opposite that AC ground should be connected to seawater and DC ground seperate and left floating. The issue with connecting grounds is that it is often don by connecting both grounds to a seacock bolt or similar. If the connection comes adrift leaving AC and DC connected to each other but no to seawater then every case and all DC equipment will potentialy at hot wire volts.

ABYC logic is that if the mains hot wire accidentally becomes connected to any exposed metal on engine or other machinery then the mains breaker should trip. If the mains safety ground connects to nothing inside the boat then such a fault would leave all the exposed metal at the mains voltage and the mains breaker might not trip. ABYC did not require an RCD on new boats until recently so many thousands of boats in the US do not have an RCD.

And many truck stop inverters will not work with an RCD. The unfiltered output switching noise often causes the RCD to trip.

[boatpoker]

Originally Posted by roland stockham

I have never understood why ABYC do this. European regs say the opposite that AC ground should be connected to seawater and DC ground seperate and left floating. The issue with connecting grounds is that it is often don by connecting both grounds to a seacock bolt or similar. If the connection comes adrift leaving AC and DC connected to each other but no to seawater then every case and all DC equipment will potentialy at hot wire volts.

Electric Shock Drowning

https://www.youtube.com/watch?v=7ndt7LGgAF8

[transmitterdan]

Originally Posted by boatpoker

Electric Shock Drowning

If ABYC really wanted to end shock drownings they would lobby for legislation mandating RCD retrofits on all freshwater marinas.

[boatpoker]

Originally Posted by transmitterdan

If ABYC really wanted to end shock drownings they would lobby for legislation mandating RCD retrofits on all freshwater marinas.

ABYC mandate is boats not marinas. That is a matter for NEC

[transmitterdan]

Originally Posted by boatpoker

ABYC mandate is boats not marinas. That is a matter for NEC

ABYC along with BOAT US and other industry leaders could drive this issue if they wanted to. It is senseless to put responsibility for swimmer safety on the shoulders of boat owners. Marinas should be made to be ashamed that they are shirking their responsibility by not addressing this issue. The technology has existed for years and it is not expensive when purchased in volume. It would cost most marinas less than a couple weeks slip lease fee to put an RCD on every pedestal.

The current state of affairs is ridiculous IMO.

[a64pilot]

Originally Posted by wingless

Yes, you are correct. My error, sorry for creating confusion.

Different green wires. One for shore power Earth ground, receptacle to galvanic isolator, then to boat AC wiring. Separate green wire for underwater metal bonding, to hull zinc and to sintered bronze hull plate.

One of those is connected to battery negative on each of the engine blocks.

Mine is the same, a green wire with a yellow stripe to every piece of underwater metal to bond them.
But as the engine is also bonded and since the DC negative is connected to the engine, and DC neg and AC neg bus bars are connected, then in fact all three are actually connected together.
The add in AC neutral is connected to all those also when on shorepower and or a properly installed inverter is operating
It would appear that all grounds to even include the AC neutral are connected together.

No what confuses me is that there is only supposed to be one place AC and DC negatives are connected, same for AC neutral.
I don’t understand why though?

So your initial statement was correct or I’m missing something.

[a64pilot]

Originally Posted by transmitterdan

It sure seems as if Magnum promotes their products as designed for the marine market segment.

https://www.magnum-dimensions.com/si...glepgs-web.pdf

They do as they apparently meet ABYC or mine does, I think.
I was speaking to the blatant labels you see plastered on simple things that have no marine requirements and have no differences, like lead acid batteries for instance, most people wouldn’t consider buying a battery that didn’t say “Marine” on the label. It’s very often done to justify a higher price, when in fact the only thing marine is the label.

It works too, average boater is convinced that there is a difference in a marine battery than a regular one and will pay way more for the label.

[Frankly]

Typically all AC grounds are connected to a common point (bus bar) and if the vessel has a bonded galvanic protection system then these are brought to a second common point. Most marine engines have the 12 Volt negative connected to the engine block and a zinc on the prop shaft so to make the bonding system work it must be connected to the engine block. Now ABYC then requires a connection between these two systems (may create corrosion poblems, but electrical safety issues rule the day).

As to AC neutrals (white conductors usually also connected to a bus bar )there is no electrical connection between the neutral and the AC ground on the vessel. Bring into the picture a source of on board AC electricity (generator or inverter) and then the required connection between AC ground and neutral surfaces. This is usually a taken care of in the transfer switch connection (automatic or manual).

IMHO in the inverter situation (Honda, Magnum, or CCC) the neutral to ground connection is not such a big deal. Why you should ask?. The reason that the ground to neutral connection is required is to provide a low resistance path for current to flow when a fault happens to conductive surfaces of an appliance. A large current will flow back down the ground conductor over to the neutral connection and the breaker will quickly open and de energize the circuit. "Safe at home". A reasonable approach for reasonable level of electrical safety. Inverters will typically not provide the level of fault current required to trip the downstream breaker because they are designed to quickly shutdown on overload, not to protect you but to protect the inverter. Does no harm to connect the neutral and ground together in this situation, but probably does not make the situation safer.

I used to design AC systems for use by Navy Divers underwater. Double insulated, ungrounded (an ungrounded system is intrinsically safer), but with high quality 5ma GFI protection. Never killed anybody AFAIK.

As others have pointed out, GFI is real protection in hazardous electrical situations. 5 mA best but 30 mA (RCD level) probably going to save most. GFI/RCD type of protection does not depend on grounds.


Frankly

[DreamWeaver III]

Depending upon the inverter, the "earth" can be sitting at half your output AC voltage.
this is generally not an issue until you have either a device that is plugged in and connected to your battery negative (boat earth) or you use shore power and the earth and neutral are tied together causing an "earth loop" whereby you are shunting power through the earth conductor of your inverter - seen it many times - this would also trip an RCD/RCBO