Bus Bar Bonding

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Chobbs

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Tampa, Florida
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ICT Project Manager and Designer
Hello,

I have a question regarding the 2020 NEC and using bus bars per 250.94(B).

It states in 250.121(B) that the metal frame of a building or structure shall not be used as an equipment grounding conductor.

Does this mean that the bus bar in 250.94(b) shall not be bonded to the structural steel of a building. Or is the connection from the bus bar considered the grounding electrode conductor and falls under 250.68 (C)(2) where it states that the metal structural frame of a building shall be permitted to be used as a conductor?

The question arises because ANSI/TIA-607 states that structural steel can be used in place of a Telecommunications Bonding Backbone. However, since the NEC has been updated, the 250.121(B) raises the question if we tie the bus bar to building steel we are violating code.

Regards,
Chris
 
Dennis Alwon

Dennis Alwon

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I think what 250.121(B) is saying is that you cannot use the building steel as an equipment grounding conductor. If for some reason you didn't have an equipment grounding conductor at your equipment in the raceway then you couldn't just jump to the steel and get an equipment ground. The equipment grounding conductor must be run together with the conductors.

That's how I see it.
 
infinity

infinity

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I don't think that you find too many places in the NEC where you cannot bond something even if it's not required.
 
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Chobbs

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Location
Tampa, Florida
Occupation
ICT Project Manager and Designer
Dennis Alwon said:
I think what 250.121(B) is saying is that you cannot use the building steel as an equipment grounding conductor. If for some reason you didn't have an equipment grounding conductor at your equipment in the raceway then you couldn't just jump to the steel and get an equipment ground. The equipment grounding conductor must be run together with the conductors.

That's how I see it.
Click to expand...

I agree with your interpretation, however I have someone telling me the conductor from the bus bar is considered an EGC and therefore it can't be bonded to the building steel.
 
tom baker

tom baker

First Chief Moderator
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Location
Bremerton, Washington
What I have seen is the bus bar is part of the GEC system. Now you may bond structural metal to the bus bar as the metal is a GE. But using the bus bar to tie to metal for the metal to be an EGC would violate 300.2 (B)
 
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Beaches EE

Senior Member
Location
NE Florida
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Electrical Engineer / Facilities Manager
Along these lines, is it permissible to bond a non-electrical piece of equipment to building steel for static discharge protection?
 
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