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3-wire 240V conversion - ground to water pipe?
- Thread starter Duemeister
- Start date
wyliesdiesels
Well-known member
It works just like any other GFCI...Oh wow. How does the GFCI circuit breaker work on the hot tub then?
Jack Ryan
Well-known member
A GFCI detects the difference in current between the line wires. Any difference is assumed to be returning via the ground (the dirt thing).Oh wow. How does the GFCI circuit breaker work on the hot tub then?
Jack
wyliesdiesels
Well-known member
earth is actually a poor conductor.... the assumption is that its returning on an unintended pathway, which is usually a grounded/bonded object such as metal raceway or plumbing...A GFCI detects the difference in current between the line wires. Any difference is assumed to be returning via the ground (the dirt thing).
Jack
Jack Ryan
Well-known member
And yet neutrals are all grounded and the protective Earth is grounded.earth is actually a poor conductor.... the assumption is that its returning on an unintended pathway, which is usually a grounded/bonded object such as metal raceway or plumbing...
Hang on to a live and a grounded conductor, I don't think you would notice the difference in impedance.
Then there are the Single Wire Earth Return (SWER) distribution systems.
Jack
wyliesdiesels
Well-known member
you clearly dont understand the reason for grounding electrodes... has nothing to do with returning current to the transformer on the pole. oh you did know that electricity returns to its source not the earth right? i sure hope so...And yet neutrals are all grounded and the protective Earth is grounded.
Hang on to a live and a grounded conductor, I don't think you would notice the difference in impedance.
Then there are the Single Wire Earth Return (SWER) distribution systems.
Jack
an SWER is not the same as a split phase electrical service with a bonded neutral and grounding electrodes that dont have current on them under normal circumstances.... apples to oranges
Jack Ryan
Well-known member
you clearly dont understand the reason for grounding electrodes... has nothing to do with returning current to the transformer on the pole. oh you did know that electricity returns to its source not the earth right? i sure hope so...
an SWER is not the same as a split phase electrical service with a bonded neutral and grounding electrodes that dont have current on them under normal circumstances.... apples to oranges
Feel better now?
I do hope you learn about ground return current through education and not through accident.
If you ground a line wire the current will return, via the ground, to the neutral. This current can trip a GFCI if present, or kill you.
Jack
wyliesdiesels
Well-known member
dude you have no clue who you are talking to.... and thing i dont know what im talking about... go look at the electrical FAQ sticky and then get back to me...
Jack Ryan
Well-known member
dude you have no clue who you are talking to.... and thing i dont know what im talking about... go look at the electrical FAQ sticky and then get back to me...
You are quoting regulations so I guess you are an electrician.
Often, ground resistance is high so there is generally a requirement for a metallic ground return else there is not sufficient ground fault current to trip a breaker. But there is enough current to harm.
This example from EEPower:
Since the earth’s resistance is high, an arrangement using the earth as the only return path to the supply source will not carry enough current to clear the fault, posing a dangerous voltage between the metal parts and the ground. Hence, such an arrangement is not an effective ground-fault current path.
For example, a 120 V circuit grounded through a 25 Ω ground rod will produce a ground-fault current of 120 V/25 Ω = 4.8 A back to the supply source. This low current magnitude will likely not trip the circuit breaker or melt the fuses.
In that example, a ground fault current 4.8A is enough to cause injury, but not enough to trip a typical breaker. It is enough current to trip a GFCI and protect a hapless human who happened to be in the way.
I am not saying that a metallic ground return is not needed, I am saying that a line connection to ground is still possible and potentially dangerous. However, despite the high resistance of an actual ground return path, there will be enough current to trip a GFCI and make the situation safe.
Jack
wyliesdiesels
Well-known member
apples and oranges. i was talking about grounding electrodes and youre talking about equipment grounding conductors. 2 different animals with different functions. go look at my post #3 in the sticky...You are quoting regulations so I guess you are an electrician.
Often, ground resistance is high so there is generally a requirement for a metallic ground return else there is not sufficient ground fault current to trip a breaker. But there is enough current to harm.
yeah thats why grounding electrodes arent for clearing fault current. thats the job of the EGC- equipment grounding conductor... under normal operations, no current should be flowing on the grounding electrode at all anyways. only time that happens is with a compromised neutral which wouldnt cause a breaker to trip either.... this is what ive been trying to explain all along and youre confusing equipment grounds and grounding electrodesThis example from EEPower:
Since the earth’s resistance is high, an arrangement using the earth as the only return path to the supply source will not carry enough current to clear the fault, posing a dangerous voltage between the metal parts and the ground. Hence, such an arrangement is not an effective ground-fault current path.
For example, a 120 V circuit grounded through a 25 Ω ground rod will produce a ground-fault current of 120 V/25 Ω = 4.8 A back to the supply source. This low current magnitude will likely not trip the circuit breaker or melt the fuses.
and nobody here was advocating using the grounding electrode or earth as the only return pathway.... but again that has nothing to do with equipment grounding conductors and fault current... the fault current trips the breaker because of the neutral bond in the panel, not because of the connection to the grounding electrode and flowing thru the earth. if the fault current flowed back to the transformer via the earth it would be bypassing the neutral bond in the panel so there would be no pathway for a fault...
a line connection to ground as in the earth or the equipment grounding conductor? youre mixing things up again...In that example, a ground fault current 4.8A is enough to cause injury, but not enough to trip a typical breaker. It is enough current to trip a GFCI and protect a hapless human who happened to be in the way.
I am not saying that a metallic ground return is not needed, I am saying that a line connection to ground is still possible and potentially dangerous. However, despite the high resistance of an actual ground return path, there will be enough current to trip a GFCI and make the situation safe.
Jack
Jack Ryan
Well-known member
apples and oranges. i was talking about grounding electrodes and youre talking about equipment grounding conductors. 2 different animals with different functions. go look at my post #3 in the sticky...
yeah thats why grounding electrodes arent for clearing fault current. thats the job of the EGC- equipment grounding conductor... under normal operations, no current should be flowing on the grounding electrode at all anyways. only time that happens is with a compromised neutral which wouldnt cause a breaker to trip either.... this is what ive been trying to explain all along and youre confusing equipment grounds and grounding electrodes
and nobody here was advocating using the grounding electrode or earth as the only return pathway.... but again that has nothing to do with equipment grounding conductors and fault current... the fault current trips the breaker because of the neutral bond in the panel, not because of the connection to the grounding electrode and flowing thru the earth. if the fault current flowed back to the transformer via the earth it would be bypassing the neutral bond in the panel so there would be no pathway for a fault...
a line connection to ground as in the earth or the equipment grounding conductor? youre mixing things up again...
I think what I said was perfectly reasonable, you are just determined to be correct by not understanding.
No doubt you'll beat your chest another time but I'm done here.