Tools are Grounded to Send the surge of electricty to earth
- Thread starter tom baker
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- Illinois
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- retired electrician
First that would assume that the code is a logical document.Okay, consider my logic.
NEC is for general public safeguarding.
Ground rod provision is stipulated in one or two of its articles.
So ground rod is also for general public safeguarding.
What is wrong in that logic?
kwired
Electron manager
- Location
- NE Nebraska
Ground rod is nothing more then an earth reference point. Resistance of the electrode to earth is what determines how effective it is at carrying current and how large of a voltage gradient will be near the electrode. Most will have a high enough resistance they are not effective substitute for ground fault clearing purposes, yet many misunderstand them to be effective for that purpose.Okay, consider my logic.
NEC is for general public safeguarding.
Ground rod provision is stipulated in one or two of its articles.
So ground rod is also for general public safeguarding.
What is wrong in that logic?
It's as if it's expected that the earth will somehow absorb the electrons and make the breaker trip.:happyno:
In remote locations where OCPD/ground fault protector such as GFCI becomes ineffective for shock protection due to long circuit length/high ground resistance, ground fault protection in that case may be made effective by decreasing the ground resistance with a ground rod so that enough leakage current flows through ground fauit protector device to operate it.
- Occupation
- Licensed Electrician
Whatever point you are trying to make would be easier to grasp if what you said made sense.
That would have to be a long ckt- the max recommended ckt length for gfci's is a couple of hundred feet or so- why not just put in another gfci at the end of that long run if in doubt about efficacy? Not seeing how a rod at the gfci location would be of any benefit.
- Location
- Massachusetts
Truthfully if the circuit is so long it needs an electrode to help the GFCI operate it would be hard to get a shock from the circuit in the first place.
K8MHZ
Senior Member
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- Electrician
I don't know how that would be by anyone that has read the NEC. It states that the earth shall not be used as an effective path for clearing faults.
(I know you know that, just making a point)
K8MHZ
Senior Member
- Occupation
- Electrician
And with that logic, wouldn't adding an electrode make the situation MORE dangerous? That is, if it would even make a difference.
- Location
- Illinois
- Occupation
- retired electrician
If you don't have enough current flow to trip a GFCI you don't have a serious shock hazard.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
There is a big difference between a GFCI not tripping because of loop resistance limiting the fault current to less than 6ma (not realistically going to happen!) and a GFCI not being usable because the long line capacitance will cause false trips at a threshold of 4ma.
Adding additional grounding or bonding is not going to help the second case.
Now if you are talking about GFP at a level of say 10% of circuit capacity instead of GFCI, then return path impedance might become an issue.
- Location
- Massachusetts
Which was my point and Don's as well
Which no one was saying but sure add more confusion to the thread
Exactly- there has to be enough current to begin with for there to be a hazard.
There is a big difference between a GFCI not tripping because of loop resistance limiting the fault current to less than 6ma (not realistically going to happen!) and a GFCI not being usable because the long line capacitance will cause false trips at a threshold of 4ma.
Adding additional grounding or bonding is not going to help the second case.
I assumed Sahib was thinking the gfci would be ineffective/problematic on very long runs, and that he thought a gr would help- now he knows that is not the case.... I think.
The problem with this myth is that it's just so pervasive- rod in "ground", "ground" wire at outlet, and I didn't mean electricians specifically, more making a generalization of the theory of those in that camp.
An OCPD in a long circuit may not provide indirect contact shock protection due to delay in fault clearing. In such a case, conductor size may be increased or a suitable parallel ground path may be formed with a ground rod. Which one to choose is an economic decision.
Sahib, adding a ground rod isn't going to do anything helpful- the earth is almost always too resistant a path for fault current- that's why we can't use it for such purpose.
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The bulk of ground resistance is at the contact of ground rod with the ground and it can be reduced and so the parallel ground path could be made effective. But still the problem is
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