electrical ground

[hitthebricks]

In a aluminum boat (Crestliner) what creates the ground for the electronics?

Thanks

HTB

[LMITOUT]

The battery.

On any boat all grounds should be connected to the negative battery terminal. Do not ground to the boat.

There is more than likely one ground wire from the battery that lands on a terminal block under the dash where all the electronics are grounded together at one spot. This is so you don't have a bunch of individual wires running back to the battery.

[Valv]

Do not ground to the boat.

Exactly !! Any black wire in your boat is the ground wire. Each electrical component will have it.

[hitthebricks]

So the battery creates enough ground for everything, (radio's, gauges,antennas,lights, whatever) because it is a DC system? I guess I don't get it, I must be eclectically illiterate.

Any help or explanation would be great.

Thanks

HTB

[CAMAN]

All electricity works on basically the same principle, and travels in a loop.

In a home system using AC it travels through the positive/hot wire into the light bulb (or whatever load you have) and back out through the negative to the power station. But if you look closely the negative and ground wires are connected to the same bar in the breaker box, and those wires are connected to a bar pounded into the ground outside your house. So in actuality the ground and negative wires do the same exact thing in your home, it's just the wire you call ground (bare or green) is used for safety incase something happens internally it is able to direct the power safely away from you.

The battery in your boat is a self contained system, it goes out the positive post, travels through the wire out to the load, leaves the load through the negative wire and returns back to the battery through the negative post.

Now if you are comparing a boat electrical system with a car electrical system, boats don't have a full "chassis ground" because of issues with electrolysis and possible corrosion problems because the boat is sitting in water. Where as cars have a chassis ground simply because it is easier and cheaper to manufacture vehicles with half the number of wires.

The reason we don't need a safety ground in a boat or vehicle is because 12 volt is considered "safe" and will not harm you if directed through you. I think its something like 50 volts or less is considered "safe".

[BobT]

I may even have some errors here but...

Quote:

In a home system using AC it travels through the positive/hot wire into the light bulb (or whatever load you have) and back out through the negative to the power station.

In AC circuits the charge is alternating positive and negative at a controlled frequency. In the US this is typically 60 hertz or 60 times a second; hence the label AC (Alternating Current). The ungrounded wire, black or “hot” wire as it is often referred to, is not just positive.

Quote:

But if you look closely the negative and ground wires are connected to the same bar in the breaker box, and those wires are connected to a bar pounded into the ground outside your house. So in actuality the ground and negative wires do the same exact thing in your home, it's just the wire you call ground (bare or green) is used for safety in case something happens internally it is able to direct the power safely away from you.

In AC circuits the grounded conductor, white wire or what is commonly and incorrectly referred to as the “neutral” conductor is not just negative. This is a current-carrying conductor very much like the ungrounded conductor.

IMPORTANT!!!

The grounded wire (white) and grounding electrode conductor (bare) DO NOT do the exact same thing. The grounded conductor is a current-carrying conductor and provides the normal closed loop for the circuit to the power source. The grounding electrode conductor by design must provide a low impedance path to the power source in order to effectively operate the OCPD (circuit breaker or fuse) in a ground fault situation and should never carry electric current under normal conditions. It is precisely this relationship that makes a GFCI function properly.

Quote:

The battery in your boat is a self contained system, it goes out the positive post, travels through the wire out to the load, leaves the load through the negative wire and returns back to the battery through the negative post.

This is debatable. The more commonly accepted theory today is electron theory and not hole theory. Since opposites attract, electron theory suggests that it is electrons flowing from the negative source where they are in abundance resulting in high negative charge to the positive terminal where there is a lack of electrons or less negative charge, which is positive by comparison.

[low277]

I agree with BobT.

I also have quite a number of books dealing with electrical theory, although I have none which are stated as fact.

[delcecchi]

I agree with BobT.

I also have quite a number of books dealing with electrical theory, although I have none which are stated as fact.

While mostly electrical current is in the form of electrons, the convention is using positive current which flows in the opposite direction from the electrons. Back in the day they guessed which was the polarity that produced the carriers and got it backwards.

For some time, engineers and technicians used to get taught differently, with engineers using "conventional current" and techs using "electron current". I hope that has gotten fixed since it used to cause confusion.

In silicon, the carriers might be positive or negative (holes or electrons). If you look at a schematic and see a diode, the arrow points in the direction of conventional current.

And in you house the safety ground bare wire and the neutral are connected together at the service box,as I recall.

Ground is arbitrary in an electronic circuit.

I can go on for a long time since I did electronics for a living for a long time.

In a boat there is a black wire return since it is not a good idea to have current flowing in the hull. And some hulls don't conduct.

[BobT]

Quote:

And in you house the safety ground bare wire and the neutral are connected together at the service box,as I recall.

This is correct; however, the incorrect statement was that the EGC (bare wire) and the grounded conductor (white wire) in a residential circuit did "exactly the same thing." They do not. They each have their specific purpose. The white wire is a current carrying conductor. The bare wire is not. I just wanted to make sure this was understood so people don't get hurt being misinformed.

[jmd1]

But the wire you run both for your boat or car have to be large enough to carry the load you want to pull. The ground wire (black) and the hot wire (red) in 12 volt system need to be same size. it is like a hose, you use 5 gallons of water and return 5 gallons of water. you would not to use a 1 inch hose to fill your bucket and a 1/4 inches hose to send it back. Doing a google search on electrical basics will yield you needed info that will help you answer some of your questions and give you a better understanding of how the whole thing works. Good Luck

[delcecchi]

Good point, the white neutral carries the return current while the bare wire is for safety and shouldn't be carrying any current.