Proper Boat Grounding

[Bugzilla46310]

Looked through some posts and some of the links in the sticky posts no longer work after a few decades! I think I know the answer but wanted to make sure. The wiring on my 1998 Sylvan 17’ Blue Fish doesn’t look up to my standards and I will most likely clean it up a bit in the spring and if any issues are found I will address those also. From what I see, the ground is never attached to the boat hull, like in a vehicle, but is isolated from the hull and only goes to the battery and related terminals. Is this a correct assumption? Thanks

 

[jlh3rd]

Thats's how it is on my '06 pontoon. I believe the correct term is "floating ground".

 

[Scott Danforth]

that is correct. except for bonding wires, you NEVER pass current thru the boat. it will literally dissolve from galvanic corrosion.

 

[dingbat]

I believe the correct term is "floating ground".

A "floating ground" is an electrical potential not physically connected to the earth/ground.

In the boat scenario, all grounds are tied to the negative post on the battery. The negative battery terminal is then grounded through the motor via the water to produce an earth ground.

Without the earth connection, there is a chance that the boat's potential could be greater than "earth" setting up a possible shock hazard.

 

[jlh3rd]

but the boat is floating...


just kid'n.

 

[jlh3rd]

umm....well, that's not what I'm finding after looking. My pontoon is DC only, but if this "grounding" to earth is through the motor/water/earth, then I can ground my negative any place on my aluminum structure. The motor is grounded to my transom so what difference does it make.
What about an RV.....a car.....
so just asking....

 

[Scott Danforth]

See post #3

 

[airshot]

See post #3

Now even more confused.....my aluminum boat has no wires connected to the aluminum hull, but it does show 12v when testing with a vom. It must be thru the SS bolts bolting the motor on to the transom.

 

[Scott Danforth]

Your hull bonding is to the battery negative

Never use the hull as a ground path

 

[jlh3rd]

I read it and again, and now it's more involved. If dingbat is right then my pontoon is shedding electrons through my aluminum toons.
Not good according to you and I agree.
But is my motor a ground source to the water/earth?....so its not a floating ground?.....

 

[Scott Danforth]

Look up the ABYC standards on electrical and bonding

 

[jlh3rd]

i understand bonding.
so there is continuity between my toons and the prop/shaft, but all grounds (black/green) should connect to a ground bar ( I installed) on a non conductive surface which is connected to bat- , which is earth grounded by my motor/toons.

to airshot : I believe this is how it is. In other words, don't ground the horn , or any other powered device to conductive components that have a path to toons or aluminum hulls.

 

[dingbat]

umm....well, that's not what I'm finding after looking. My pontoon is DC only, but if this "grounding" to earth is through the motor/water/earth, then I can ground my negative any place on my aluminum structure. The motor is grounded to my transom so what difference does it make.

Suggest your read up on electrical potential (voltage)

No two points on your aluminum structure will have the same electrical potential. It's the difference in electrical potential (voltage) between the points that causes electrolysis.

This is why all grounds are tied together at a common point, IE motor and buffered with anodes.

 

[Bugzilla46310]

that is correct. except for bonding wires, you NEVER pass current thru the boat. it will literally dissolve from galvanic corrosion.

The bonding wire is confusing me. I have been on ASME Standard committees so I‘m a bit critical on the clarity of standards. Assuming the reference below is actually from the ABYC standard, the committee that wrote this standard definitely needs help on clarifying their standard as in my opinion it is written horribly. 11.4.9 and 11.4.10 is a prime example. 2 different definitions for the same term. This is how you blow things up in industry!

My interpretation:
Electrical Grounding:, All electrical items are grounded to the battery via a black wire.
Structural Grounding: All structural items are grounded to the motor via a lug on the motor, with a green wire.

Are both of these grounds connected to the battery, or just the electrical ground? See 11.4.11 below. The site referenced below shows both connected to the battery.

If both are connected to the battery, then is it just 2 separate grounding circuits, one for electrical (black wire) and one for structural (green wire), correct?

Below is from the https://newboatbuilders.com/pages/electricity6.html, supposably from the ABYC standard.

In the Bonding description, what is the earth ground?

Bonding: A separate system electrically connecting all metal fittings on the boat that are in contact with the water, including the sacrificial anode(s), and connecting them to the earth ground, so they are all at the same voltage potential, zero. There should never be any current in the bonding system. The resistance of this circuit should be less than one (1) ohm.

Bonding wire: The bonding wire, also a green wire, is connected to earth ground at the engine negative terminal or the grounding buss.

11.4.9 DC Grounded Conductor - a current carrying conductor connected to the side of the power source that is intentionally maintained at boat ground potential.

11.4.10 DC Grounding Conductor - a normally non current carrying conductor used to connect metallic non current carrying parts of direct current devices to the engine negative terminal, or its bus.

11.4.11 Engine Negative Terminal - the point on the engine at which the negative battery cable is connected.

 

[jlh3rd]

Suggest your read up on electrical potential (voltage)

No two points on your aluminum structure will have the same electrical potential. It's the difference in electrical potential (voltage) between the points that causes electrolysis.

This is why all grounds are tied together at a common point, IE motor and buffered with anodes.

I got it....and that's how my pontoon is wired.

 

[jlh3rd]

The bonding wire is confusing me. I have been on ASME Standard committees so I‘m a bit critical on the clarity of standards. Assuming the reference below is actually from the ABYC standard, the committee that wrote this standard definitely needs help on clarifying their standard as in my opinion it is written horribly. 11.4.9 and 11.4.10 is a prime example. 2 different definitions for the same term. This is how you blow things up in industry!

My interpretation:
Electrical Grounding:, All electrical items are grounded to the battery via a black wire.
Structural Grounding: All structural items are grounded to the motor via a lug on the motor, with a green wire.

Are both of these grounds connected to the battery, or just the electrical ground? See 11.4.11 below. The site referenced below shows both connected to the battery.

If both are connected to the battery, then is it just 2 separate grounding circuits, one for electrical (black wire) and one for structural (green wire), correct?

Below is from the https://newboatbuilders.com/pages/electricity6.html, supposably from the ABYC standard.

In the Bonding description, what is the earth ground?

Bonding: A separate system electrically connecting all metal fittings on the boat that are in contact with the water, including the sacrificial anode(s), and connecting them to the earth ground, so they are all at the same voltage potential, zero. There should never be any current in the bonding system. The resistance of this circuit should be less than one (1) ohm.

Bonding wire: The bonding wire, also a green wire, is connected to earth ground at the engine negative terminal or the grounding buss.

11.4.9 DC Grounded Conductor - a current carrying conductor connected to the side of the power source that is intentionally maintained at boat ground potential.

11.4.10 DC Grounding Conductor - a normally non current carrying conductor used to connect metallic non current carrying parts of direct current devices to the engine negative terminal, or its bus.

11.4.11 Engine Negative Terminal - the point on the engine at which the negative battery cable is connected.

yep confusing......so, this is my common man explanation...pontoon.

12v DC
All powered equipment sends current out of itself when on. This current is negative (ground). This current needs to meet either at a grounding isolated buss bar or directly to the negative battery post or to the engine ground.
If I connect a negative return from a powered source to my "hull" , I am inducing current through my hull to ground. It'll take the least resistive path, which is to water. I'm inducing a potential current difference....two paths....one directly to the hull and the other from battery through motor/transom/prop.......since it is kinda confusing, just make sure all grounds are to the same final connection...battery/motor.....
I can't program a computer so I follow the rules to operate it.

bonding....just an example-
I installed my hot tub years ago so I needed to learn how.
AC high voltage high amps.
One requirement is that all touchable conductive structures touchable from inside the tub have to be bonded to the tub which is , of course, connected to the home panel. The home panel neutral and ground buss bars are "bonded " together in the panel. I have an aluminum gazebo right next to the tub. All structures are on a wooden structure. There is a "bonding" lug on the hot tub. So there is a bonding wire, think it's 4 gauge whatever the instructions required, from that structure to my hot tub.
Although my tub is GFCI protected, if my water was somehow energized and I touched that gazebo, maybe under a weird circumstance i could become the conductor......gazebo's mounted on wood, but not taking that
chance......so it's bonded to the tub which is connected to earth ground through my main panel....

any help?

 

[jlh3rd]

so all grounding wires on my pontoon meet on an isolated buss bar, which is connected to my battery, which is connected to the motor.


if I'm wrong, speak up.

 

[Scott Danforth]

bonding wires (Green or Green with yellow stripe) tie the hull, motor, zincs water, etc. to the negative side of the battery. they are there to tie them all together to the same potential for galvanic reasons. the potential between the ground terminal of the battery and the hull/motor/etc should be 0.00. this is to minimize corrosion.

grounding wires (black) tie the current paths from any electrical load back to the battery so you do not run current thru the hull. all loads must have a complete loop of power source to circuit breaker to load to ground.

the reason you do not want to run any current thru the hull is simple. it will galvanically eat the hull. if you attempt to use the hull as a current return to the battery, it will "work" for a little while, however your aluminum hull will look like it was soaked in acid after a very short period of time.

 

[airshot]

Glad I was a toolmaker, to much weird terminology in electrical explanations for me....lol....

 

[jlh3rd]

I dislike trouble shooting circuits because you can't see electricity.

to scott: my toons have no bonding wire as such. Should there be?...or is the transom/ motor connection the "bonding".