Building steel to machine

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ADub

ADub

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Location
Midwest
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Estimator/Project Manager
I have a manufacturer asking me to bond a drive cabinet to building steel and essentially the GE system. This is a new one for me so I'm wondering how common it is. I've driven ground rods for plenty of similar equipment but never this. My question is what the added benefit would be and also how to logically size the bond since there is no specification for that part. It's fed from a 400 amp breaker so my first thought is to simply pipe up to the closet I beam and run a #3.


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IMO there is no benefit. Make sure that you bring in the EGC with the incoming power. That is the important thing.

Even though it probably serves no useful purpose, it is not an unheard of request by machine builders. About the same utility as driving one or more ground rods by the machine.
 
A vehicle assembly constructed in our area had as a requirement a 3/0 Cu bond from every MCC to a building column that was bonded to a ground ring. The MCC bonds were often a run in excess of 100 ft. and an individual bond was required from each cabinet.
Lots of E/Cs missed that requirement in the specs. OUCH!
 
petersonra said:
IMO there is no benefit. Make sure that you bring in the EGC with the incoming power. That is the important thing.

Even though it probably serves no useful purpose, it is not an unheard of request by machine builders. About the same utility as driving one or more ground rods by the machine.
Click to expand...

That was my thought too. Whenever I'm asked to drive a rod for a machine I just smile and shake a tree


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ADub said:
I have a manufacturer asking me to bond a drive cabinet to building steel and essentially the GE system. This is a new one for me so I'm wondering how common it is. I've driven ground rods for plenty of similar equipment but never this. My question is what the added benefit would be and also how to logically size the bond since there is no specification for that part. It's fed from a 400 amp breaker so my first thought is to simply pipe up to the closet I beam and run a #3.


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Click to expand...

Building steel is part of the GE system, seems to me one bond to steel is all that is needed to comply with their wishes.
 
kwired said:
Building steel is part of the GE system, seems to me one bond to steel is all that is needed to comply with their wishes.
Click to expand...

I thought that's what I said, or at least tried to. They are asking for a bond to building steel and, in turn, the buildings grounding electrode system. I was wondering what the benefit would be in doing this, or is their a benefit at all? The unit is solidly connected with an equipment ground already. I bet it's better than a ground rod though


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ADub said:
I thought that's what I said, or at least tried to. They are asking for a bond to building steel and, in turn, the buildings grounding electrode system. I was wondering what the benefit would be in doing this, or is their a benefit at all? The unit is solidly connected with an equipment ground already. I bet it's better than a ground rod though


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It is their benefit when it comes to warranty work. You don't connect like they want, even if it makes no sense, they get out of warranty work.
 
One CNC machine retrofitter demanded a separate GE for each machine.

If one walked out the back of the factory, there were dozens of Grods all along the building

110.3B boldly going where no theory has gone before....

~RJ~
 
romex jockey said:
One CNC machine retrofitter demanded a separate GE for each machine.

If one walked out the back of the factory, there were dozens of Grods all along the building

110.3B boldly going where no theory has gone before....

~RJ~
Click to expand...

That's rough. I just drill a hole in the floor and bash away


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