Working in a manufacturing plant moving equipment(Melton Welders) and each piece of welding equipment has a ground rod installed and connected via bare cu conductor to a mechanical lug on welder frame. The supply voltage to equipment is 480V 3 ph with ground. I'm wondering if the ground rod is required since there is an EGC run with the supply conductors? Is the current installation considered a parallel path to ground? Does 250.32(B)(1) apply?
Ground rod on equipment
- Thread starter cds9044
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250.32 does not seem to fit the installation you describe. I think 250.54 would be more in line with what you are describing.
As long as the EGC is attached to the ground rod I see no issues.
Pete
p.s. the NEC would not require the ground rod but the manufacturers installation instructions may. 110.3(B)
As long as the EGC is attached to the ground rod I see no issues.
Pete
p.s. the NEC would not require the ground rod but the manufacturers installation instructions may. 110.3(B)
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- Location
- New Jersey
- Occupation
- Journeyman Electrician
Auxiliary ground rods are fine as long as they're not used instead of an EGC.
We're checking with manufacturer to see if they require them. Thanks.
stevebea
Senior Member
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- Southeastern PA
I agree, Art. 250 say all electrodes must be bonded together. Some manufactures will void warranty if a ground rod is not driven at the equipment.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
I would know of no purpose a ground rod would serve to be connected to a welder:?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
An auxiliary bonding electrode is not required to be connected to the grounding electrical system. The graphic is from before they changed the name of the electrode.
stevebea
Senior Member
- Location
- Southeastern PA
An auxiliary bonding electrode is not required to be connected to the grounding electrical system. The graphic is from before they changed the name of the electrode.
While it may not be required would it not be a good idea due to the difference in potential in the event of a ground fault or transient? Just thinking out loud.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
With a ground fault the EGC is the lowest impedance path back to source, the Ground rod will do little to nothing if the EGC path is not there, that was the reason for my statement in post 6.
Transient currents are also seeking a return to what ever source that generated it, not Earth, this is a myth to think that the electrons are seeking Earth, only a direct lightning strike will seeking a return to Earth, but the many induced circulating currents also produce by lightning will also not seek Earth, but are circulating within circuits of a building.
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stevebea
Senior Member
- Location
- Southeastern PA
Yea.... I understand the EGC is the lowest impedance path...... what I dont understand is why equipment with sensitive electronics needs auxiliary ground rods, but I know it to be true. I do work at a facility where they do several different kinds of coatings. A couple years ago I wired for two new pieces of equipment. They had a heck of a time with reboots and data errors until they did auxiliary grounding. I'm told that took care of their problems.:?
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
There was a study done by the electric industry - I sent a copy to Mike Holt and he quotes it in his presentations - about installing a ground rod for industrial equipment.
Sometimes it helps (data errors)
Sometimes it makes it worse
Sometimes no change
What can happen is the ground rod sets up a path for lightning to enter to machine since its not at the same potential as the building ground, and can cause issues.
My comment is make sure you understand this ground rod is not present to clear a fault.
Sometimes it helps (data errors)
Sometimes it makes it worse
Sometimes no change
What can happen is the ground rod sets up a path for lightning to enter to machine since its not at the same potential as the building ground, and can cause issues.
My comment is make sure you understand this ground rod is not present to clear a fault.
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