Ground Buss-Paint Mix Room

[augie47]

I am inspecting paint mix room at an auto manufacturing facility.
The room has been classified at Class 1 Div I and is wired accordingly.
There is a copper buss, bonded to the building steel/grounding electrode system, install 12" AFF on all walls.
An on site engineer is asking that all electrical components be bonded to that bar.
We do not address contractual issues or issues other than NEC.
Is there any NEC requirement for this to be done ?

Out of curiosity, is that required by any other NFPA Code ?

 

[marti smith]

250.58, reflect on 250.53(A) although hard to say without seeing it.

 

[jdsmith]

I am inspecting paint mix room at an auto manufacturing facility.
The room has been classified at Class 1 Div I and is wired accordingly.
There is a copper buss, bonded to the building steel/grounding electrode system, install 12" AFF on all walls.
An on site engineer is asking that all electrical components be bonded to that bar.
We do not address contractual issues or issues other than NEC.
Is there any NEC requirement for this to be done ?

Out of curiosity, is that required by any other NFPA Code ?

As long as all of the electrical equipment is bonded through a grouding conductor, RGS conduit, etc. I am not aware or any NEC or NFPA requirement that equipment is also connected to a copper bus bar system. In the petrochemical business we have API 540 that recommends connecting everything in the electrical room to a copper bus bar in addition to typical grounding. It also recommends bonding motor frames to a ground ring or ground grid in addition to the ground that comes into the terminal box with the feeder. API RP 540 also has a bunch of other bonding recommendations for steel, process vessels, tanks, etc. I'm not aware of anything within NFPA that would require or recommend that equipment is bonded redundantly.

 

[sgunsel]

NFPA 33 Standard for Spray Application Using Flammable or Combustible Materials applies to a paint mix room. NEC Article 516 is extracted from NFPA 33. NEC Articles 250 and 501 govern equipment grounding.

All conductive objects in a paint mix room are required to be bonded and grounded since paint handling (pouring, mixing, etc.) generates static electricity that can ignite flammable vapors. There is no "bus bar" requirement. A bus bar is typically used to provide bonding and grounding for items as drums, pails, tanks, mixers, and other portable equipment or conductive objects that may be present to prevent the accumulation of static electrical charge. It would not normally be an equipment grounding conductor. To be effective for static control, the resistance to ground is required to be less than 1 megohm (yes, that is 1,000,000 ohms!).

See NFPA 77, Recommended Practice on Static Electricity for more information on the generation and control of static electricity.