AC ground question?

[er9]

How does the AC voltage transfer to the earth ground wire if there is a fault in the wiring and the current cant return via the neutral wire? OR if thats not how it happens...how does the ground wire neutralize the dangerous current?

I realize the neutral and earth are bonded at the breaker box or at the source but that means AC current has to somehow get onto the ground wire (green) to make it back to the source which i thought was a big NO,NO.

having trouble wrapping my head around the function of the green ground safety wire.

[goboatingnow]

The primary historical purpose of the earth wire , is that if a fault connects the live wire to something that is connected to the earth wire, like a metal body etc , then currents flows such that the fuse blows, thereby disconnecting the live . This is to avoid the fault current flowing through you , an altogether unpleasant experience

Normally return current flows back through the neutral line not the protective earth line, the neutral line typically returns to the local transformer

[Cat36Mahalo]

On a boat the ground is made at the shore end for shore connections... or in the inverter / generator for AC power developed on board.

The ground is there Incase the hot accedently shorts or leaks to the case ( esp when electric tool/fans... were made of metal). The fact that GFI breakers and outlets exist is proof that it still happens.

[Frankly]

1. Typically there is only one ground system even in the face of multiple power sources.

2. Typically the neutral and ground are connected at the currently producing source of electricity and other sources have the ground neutral connection lifted.

3. The ground system connects all conductive surfaces and under normal function is conducting no current.

4. When a fault condition develops (short that can electrify the conductive surface), a large current will flow back through the ground system and back to the ground neutral connection and trip the circuit breaker removing the voltage that has shown up on the conductive surface rendering that surface harmless. No power but no shock.

There are times when the above scenario is not tolerable (ie shutdown of an essential motor), that is where an ungrounded system might replace the grounded system. Ungrounded does not mean no ground system, just that the neutral to ground connection does not exist.


Frankly

[delmarrey]

One thing you can do, if you have a lead keel, is to run a ground wire to a keel bolt. Upgrade the wire by a couple gages from the 120V wiring.

[er9]

Originally Posted by delmarrey

One thing you can do, if you have a lead keel, is to run a ground wire to a keel bolt. Upgrade the wire by a couple gages from the 120V wiring.

wouldnt that put hot AC directly into the water?

[er9]

thanks for replies, now it makes sense that its a path to a breaker.

[delmarrey]

Originally Posted by er9

wouldnt that put hot AC directly into the water?

Better then into your hand. If your in a marina, you can hook it to the 120V AC ground.

[er9]

Originally Posted by delmarrey

Better then into your hand. If your in a marina, you can hook it to the 120V AC ground.

Ah! i see. maybe a good way to get rid of the barnacles, just flip the switch every once in a while while at anchor.

[delmarrey]

Originally Posted by er9

Ah! i see. maybe a good way to get rid of the barnacles, just flip the switch every once in a while while at anchor.

Let’s just hope you don’t have any short circuits. I lost a shipmate to a bad drill motor.