Equipment Grounding

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Electriman

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Greetings,

I was wondering if I can find out NEC position on running a separate ground connection for each piece of equipment with in a factory or facility. My concern is about metallic equipment which can split them in two categories:

a) Metallic equipment that need power
b) Metallic equipment that don't require power

For group a, there is the ground cable along with power cable that I can use to ground the equipment, I was wondering if this is enough or do I still have to bring a separate ground cable and tie the equipment to ground?

What is my job for group b equipment? Can I leave them alone with no ground connections?

My concern is in industrial applications but we can talk about commercial and residential applications as well.

I would like to know what is the minimum requirement to meet the NEC.

Thanks every one in advance.
 
I believe you are talking about bonding, not grounding but, i could be wrong.
Used to work in a machine shop that was totally powered by belt driven systems and powered by a steam engine. Boss still required bonding on every machine and that it be checked every month. Said otherwise it built up static charges. But, never found anything in code books on it.

That said, I know there are many machines in a factory that are bonded even though they have a ground and a neutral. See nothing wrong with that approach but do not know if it is in code books.
 
Adamjamma said:
I believe you are talking about bonding, not grounding but, i could be wrong.
Used to work in a machine shop that was totally powered by belt driven systems and powered by a steam engine. Boss still required bonding on every machine and that it be checked every month. Said otherwise it built up static charges. But, never found anything in code books on it.

That said, I know there are many machines in a factory that are bonded even though they have a ground and a neutral. See nothing wrong with that approach but do not know if it is in code books.
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I believe bonding means connect to metallic parts together. Grounding means connect a metallic part to ground grid or ground rod(s).
 
Electriman said:
...For group a, there is the ground cable along with power cable that I can use to ground the equipment, I was wondering if this is enough or do I still have to bring a separate ground cable and tie the equipment to ground?
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The EGC with the cable is enough. Running a separate EGC back to the main service is generally prohibited. Running a separate grounding wire to an electrode, such as a rod, is actually permitted by code for equipment, but is stupid to do.

What is my job for group b equipment? Can I leave them alone with no ground connections?
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Maybe, maybe not. Some items, such as metal piping systems, are required to be bonded by the NEC. Other stuff, if it's 'likely to become energized', should probably be bonded. The part in quotes is subjective to your perception.
 
Electriman said:
Greetings,

I was wondering if I can find out NEC position on running a separate ground connection for each piece of equipment with in a factory or facility. My concern is about metallic equipment which can split them in two categories:

a) Metallic equipment that need power
b) Metallic equipment that don't require power

For group a, there is the ground cable along with power cable that I can use to ground the equipment, I was wondering if this is enough or do I still have to bring a separate ground cable and tie the equipment to ground?

What is my job for group b equipment? Can I leave them alone with no ground connections?

My concern is in industrial applications but we can talk about commercial and residential applications as well.

I would like to know what is the minimum requirement to meet the NEC.

Thanks every one in advance.
Click to expand...

Good questions, basically NEC is concerned mainly about fault path which is the EGC. In heavy industry, it is customary to also provide an equipotential plane - i.e. grounding grid - to maintain a certain ohmic level across the facility. But this is normally dictated by the clients specification and is not a code requirement.
 
Electriman said:
No other comments?
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everything bonded individually to building metal (I-beam, etc), and then that bldg metal tied well to ufer and some ground rods. sounds good to me.

also helps to remove ground loops.
 
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