Objectionable Current

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czars

Czars
Location
West Melbourne, FL
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Florida Certified Electrical Contractor
Does the NEC define "Objectionable Current? I can't find a definition in Article 100 nor in Article 250.6 where the article is titled "Objectionable Current" (in the 2008 NEC). Is there an acceptable definition in any other reference?
 
IMO 250.6(C) would indicate that any current other than that needed to facilitate the operation of the OPD would be considered "Objectionable".
 
Chris,
IMO 250.6(C) would indicate that any current other than that needed to facilitate the operation of the OPD would be considered "Objectionable".
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If we apply that idea then we can't use any grounding electrode conductors as all grounding electrode conductors carry some current and this current has nothing to do with the operation of the OCPDs.
 
don_resqcapt19 said:
Chris,

If we apply that idea then we can't use any grounding electrode conductors as all grounding electrode conductors carry some current and this current has nothing to do with the operation of the OCPDs.
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I understand your point Don that some current will flow through all available paths. But your talking theory(reality).The OP is looking for a NEC reference.
 
NEC does not tell what Objectionable Current is, but with credit to Mike Holt, here are some examples:
A neutral to ground connection in a panelboard or disconnect that is not at the service.
A neutral to ground connection in a separate building.
A generator with a system bonding jumper where it is not a SDS.
Installing the system bonding jumper at the transformer and first disconnect for a transformer
 
Personally, I would say the current that flows on a city water pipe, because of code requirements to bond it, would be considered objectionable
 
Chris,
But your talking theory(reality).The OP is looking for a NEC reference.
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There isn't one...this is subjective and left to the user and AHJ to work out what is objectionable current and what should be done, if anything, to eliminate or minimize it.
 
Iraqelect said:
Personally, I would say the current that flows on a city water pipe, because of code requirements to bond it, would be considered objectionable
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The NEC only requres a grounding electrode connection to a water pipe when it meets the requirements of 250.52(A) IE ten feet of metallic pipe in contact with the earth. The NEC does require in 250.104 a metal water piping system to be bonded.
And the American Water Works Association does not water water pipes used as a ground, as one meter reader a day is shocked. They recommend a non metallic spacer be installed at least ten feet from the building.
The AWWA may consider this current to be objectionable, but the NEC requires the connection.
 
an ?objectionable current? is simply any level of current for a given electrical installation that would pose an electric shock or fire hazard and/or impede the ability of the grounding system to perform its intended functions as specified in 250.4.
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That is much clearer now. :roll:
 
Objectionable Current falls under the same definition for workmanship, exposed to physical damage, and nearest point of entry.

"I don't know what it is or how to explain it, but I know it when I see it."
 
IEEE 'Orange Book' has a definition of sorts:

That neutral currents that flow through paths other than the intended
grounded (neutral) circuit conductors during normal operation of a system will
be deemed objectionable if they contribute to any of the following:
(1) Interference with the proper operation of equipment, devices, or systems
that are sensitive to electromagnetic interference, such as electronic equipment,
communications systems, computer systems, etc.
(2) Interference with the proper sensing and operation of ground-fault
protection equipment.
(3) Arcing of sufficient energy to ignite flammable materials.
(4) Detonation of explosives during production, storage, or testing.
(5) Overheating due to heat generated in raceways, etc., as a result of stray
current.
 
Marc,
The code does not completely agree with item #1 from the Orange book.
250.6(D) Limitations to Permissible Alterations The provisions of this section shall not be considered as permitting electronic equipment from being operated on ac systems or branch circuits that are not grounded as required by this article. Currents that introduce noise or data errors in electronic equipment shall not be considered the objectionable currents addressed in this section.
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don_resqcapt19 said:
Marc,
The code does not completely agree with item #1 from the Orange book.
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How either text defines it is of little concern to me, personally. I was just throwing it into the mix, since I remembered "objectionable currents" in the table of contents in the Orange Book. I guessed that not many people would have that book, or even remember that it has a section on it. I suspect very much that the Emerald Book does as well, but I didn't check.
 
u ask for it

u ask for it

1 - objectional current is when power surge blows your computer
2- objectional current is when the dog hikes his leg on electric fence
3- objectional current is when you think its safe to touch the neutral wire
but its a long distance to the box and the current decides its easier to
go thru you since you have other hand around the conduit.
 
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