Why we ground electrical systems (2015)
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Why we ground electrical systems (2015)
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Re: Why we ground electrical systems (2015)
#2I'm actually the person who wrote this Reddit post. I'd never heard of Hacker News before, but someone messaged me on Reddit telling me this 4 year old post just surfaced over here.
Let me know if you have any questions about electrical theory or installation, or anything else!
Re: Why we ground electrical systems (2015)
#3"Since the ground-fault current path has inherently much higher resistance than the neutral wire, the amount of current flowing through the circuit jumps enormously during a ground-fault."
This is incorrect (probably a typo) - the GFC ensures there is a very low resistance path to source, which ensures a current spike that is sufficient to blow the fuse.
Re: Why we ground electrical systems (2015)
#4This blew my mind. So the white wire (neutral) is actually what I thought the ground was (connected to earth) and the “ground” wire (usually bare or green) is a conductor for clearing ground faults and isn’t connected to earth.
Marvelous explanation.
Re: Why we ground electrical systems (2015)
#5"Since the ground-fault current path has inherently much higher resistance than the neutral wire, the amount of current flowing through the circuit jumps enormously during a ground-fault." This is incorrect (probably a typo) - the GFC ensures there is a very low resistance path to source, which ensures a current spike that is sufficient to blow the fuse.
Yeah, that was a typo on my part. I didn't notice it at first, and it's now been so long since I posted it that I would feel disingenuous editing it. I think someone pointed out the typo in the comments.
Re: Why we ground electrical systems (2015)
#6This blew my mind. So the white wire (neutral) is actually what I thought the ground was (connected to earth) and the “ground” wire (usually bare or green) is a conductor for clearing ground faults and isn’t connected to earth. Marvelous explanation.
Thanks! In my 11 year experience in the electrical industry I have come to realize that there is a LOT of misinformation about how electrical systems work, and even the most experienced veterans in the field often don't really understand it.
Re: Why we ground electrical systems (2015)
#7I'm actually the person who wrote this Reddit post. I'd never heard of Hacker News before, but someone messaged me on Reddit telling me this 4 year old post just surfaced over here. Let me know if you have any questions about electrical theory or installation, or anything else!
Question with myth #1 that "electricity is trying to get to ground". Would that be an accurate statement if you replaced "ground" with a place of lower electrical potential?
Or can you elaborate but the meaning that it's trying to get back to it's source?
Re: Why we ground electrical systems (2015)
#8This blew my mind. So the white wire (neutral) is actually what I thought the ground was (connected to earth) and the “ground” wire (usually bare or green) is a conductor for clearing ground faults and isn’t connected to earth. Marvelous explanation.
Thanks! In my 11 year experience in the electrical industry I have come to realize that there is a LOT of misinformation about how electrical systems work, and even the most experienced veterans in the field often don't really understand it.
So what would be the potential consequence if I didn’t connect the “ground” wire (green or bare) to the little brass ground screw on (let’s say) a ceiling fan when installing it?
Re: Why we ground electrical systems (2015)
#9I'm actually the person who wrote this Reddit post. I'd never heard of Hacker News before, but someone messaged me on Reddit telling me this 4 year old post just surfaced over here. Let me know if you have any questions about electrical theory or installation, or anything else!
Question with myth #1 that "electricity is trying to get to ground". Would that be an accurate statement if you replaced "ground" with a place of lower electrical potential? Or can you elaborate but the meaning that it's trying to get back to it's source?
Well, electrical potential is only defined as a relation between two points. So the neutral point on a transformer, for example, doesn't have any electrical potential in and of itself. It has electrical potential with relation to, say, the termination point of one of the phases.
The electrical potential between any two given points is dependent on the impedance along the pathway between the two. The lower the impedance, the lower the potential (or work/energy needed to move current). So, yes, in a way electricity wants to get to the point with the lowest potential, but that point will always be the point where the electricity originates.
I was a little vague with "where the electricity originates" because that could be a number of things. It could be a battery, a transformer, a generator, a turbine, a dynamo, etc. Whatever is creating the difference in potential between two points is the "source" of the electricity.
Re: Why we ground electrical systems (2015)
#10Earlier quoted context omitted.
Thanks! In my 11 year experience in the electrical industry I have come to realize that there is a LOT of misinformation about how electrical systems work, and even the most experienced veterans in the field often don't really understand it.
So what would be the potential consequence if I didn’t connect the “ground” wire (green or bare) to the little brass ground screw on (let’s say) a ceiling fan when installing it?
From my understanding, if the hot wire (black) were to come in contact with a piece of metal on the fan it would build up electrical charge and or allow for current to pass through the piece of the fan. Then if you were on a ladder fixing the fan and touched that piece of metal you would become a path for electricity to pass through to a lower potential.