Isolating Transformers, The Earth wire connection conundrum

[transmitterdan]

OMG what a lot of confusion.

An RCD works with 2 wires and 2 wires only. It detects whether any current in one wire is not equal to the other wire. It assumes (with no way to know for sure) that the missing current is flowing in a person causing a shock. It opens both wires when it detects this imbalance is above some prescribed limit (typically a few milliamperes but much less than 0.1A). It is no more complicated than that.

[chala]

Originally Posted by DotDun

If you examine your own diagram, you'll notice the ground wire has absolutely nothing to do with the how the gfci works. The gfci looks for an imbalance of current between the wires labeled "L" & "N". If it detects an imbalance of greater than 5ma (in the US), it opens both "L" & "N". The 3rd wire has no affect on the operation. The leakage could be to the case of another appliance plugged into a completely separate circuit.

Kirchhoff's First Law

Originally Posted by DotDun

Also, don't assume, but please review and understand that electric current flow requires a 'circuit', a complete path from the source and back to the source.

Are you contradicting your self?

[chala]

Originally Posted by transmitterdan

OMG what a lot of confusion.

An RCD works with 2 wires and 2 wires only. It detects whether any current in one wire is not equal to the other wire. It assumes (with no way to know for sure) that the missing current is flowing in a person causing a shock. It opens both wires when it detects this imbalance is above some prescribed limit (typically a few milliamperes but much less than 0.1A). It is no more complicated than that.

So there is an imbalance of 10 milliamps between the 2 wires how does that 10 milliamps return to the supply?

[sailorchic34]

Originally Posted by chala

Kirchhoff's First Law

Non Sequitur

With the wet basement floor proposed before with a GFI protected circuit, part of the current flows back to source via a ground loop, the rest returns through the 2 conductors, the sum balances, but the current flow is unbalanced in the two wires so the GFI trips.

The 10ma's is flowing in the ground loop from wire/case through your body to wet basment floor and back to center tap on transformer via ground rod.

The Ground wire does nothing to trip a GFI. Its there to trip a circuit breaker on fault.

Really this is basic basic electrical.

[transmitterdan]

Originally Posted by chala

So there is an imbalance of 10 milliamps between the 2 wires how does that 10 milliamps return to the supply?

The RCD does not know how it returns and neither does it care. It just detects the imbalance.

[pbiJim]

Originally Posted by sailorchic34

Non Sequitur

With the wet basement floor proposed before with a GFI protected circuit, part of the current flows back to source via a ground loop, the rest returns through the 2 conductors, the sum balances, but the current flow is unbalanced in the two wires so the GFI trips.

Unless nearly equal current flows from each leg through the person in the wet basement to ground, in which case, a shock occurred & the GFCI knows nothing about it.

This doesn't mean that the ground wire would have fixed the problem, It's just a detail that I noticed had been omitted.

[transmitterdan]

Originally Posted by pbiJim

Unless nearly equal current flows from each leg through the person in the wet basement to ground, in which case, a shock occurred & the GFCI knows nothing about it. This doesn't mean that the ground wire would have fixed the problem, It's just a detail that I noticed had been omitted.

Except that is not possible. If there is equal current in the two wires then there can be no current in the ground. Only the unequal part can be in the ground. The GFI will definitely detect the imbalance.

[chala]

Originally Posted by FlyingCloud1937

So now we have an A Real Earth Potential, by passing everything that the IT is to protect against.
Lloyd

I agree.

Now we have an isolation transformer, an inverter, an autotransformer.

Not really in the spirit of

Originally Posted by Saltyhog

some of us are simply unwilling to add 60 lb. chunk of iron to our boats

And until we know more about the internal wiring of the above the risk quoted below remain and the wiring is unsafe

Originally Posted by pbiJim

Dave,
Are you saying that an appliance can not leak current to ground simply because it's power source is the floating secondary winding of an isolation transformer?

In the case of a refrigerator that has a steel shell that happens to touch some metal part of the boat, if the compressor motor leaks some current to the metal shell, would that not be an example of current leaking to ground?

If a hot plate were also in use & the other power leg leaked current in that appliance, would that not create a hazard for a person holding a pan to fry some eggs while touching a metal surface in the boat, or reaching to grab another egg out of the refrigerator?

My concern would be that just because a secondary winding was not grounded at the transformer, does not mean that an appliance down stream can not create a ground loop there.

[chala]

Originally Posted by transmitterdan

The RCD does not know how it returns and neither does it care. It just detects the imbalance.

You did not reply to the quesrion and I suppose you do not know either. smile

[transmitterdan]

Me give up...

[chala]

Originally Posted by sailorchic34

Non Sequitur

With the wet basement floor proposed before with a GFI protected circuit, part of the current flows back to source via a ground loop, the rest returns through the 2 conductors, the sum balances, but the current flow is unbalanced in the two wires so the GFI trips.

The 10ma's is flowing in the ground loop from wire/case through your body to wet basment floor and back to center tap on transformer via ground rod.

The Ground wire does nothing to trip a GFI. Its there to trip a circuit breaker on fault.

Really this is basic basic electrical.

So 2 conductors plus center tap wire via ground rod , that 3 no?

[chala]

Originally Posted by transmitterdan

Me give up...

Do not you may still learn something.

[sailorchic34]

Originally Posted by pbiJim

Unless nearly equal current flows from each leg through the person in the wet basement to ground, in which case, a shock occurred & the GFCI knows nothing about it.
.

Not possible in a residential location. You have a hot and neutral as the two wires. Neutral and ground are at the same potential. So you never get balanced flow in the two wires and shock. Only from hot through a ground loop..

The IT has two hots at opposite ends of phase. No ground loop is available to conduct so no ground loop current flow happens.

GUY's this is BASIC electrical, not even electrical 101.

Like transmitterdan. I to am SO done.

[sailorchic34]

Originally Posted by chala

So 2 conductors plus center tap wire via ground rod , that 3 no?

Not really. In us power you have two 120V legs with a center tap at 0V. So leg to leg is 240V and leg to center tap which is neutral is 120V. So neutral is the center tap and the other wire is a hot 120V. By adding a ground rod to the center tap you now have a ground loop potential. That is how older homes were wired. But only two wires were run.

Newer homes have added a 3 wire which is ground referenced same a neutral. So...

Oh never mind. Bye

[goboatingnow]

Jerpers Chala why not listen , there are 2-3 people trying to explain this to you Chala and you insist on confusing things to the point where people are leaving the thread

Why are you doing this , when you clearly don't understand electrical first principles

Dave