May become energized by wiring that is attached to the steel...or may become energized by a faulty extension cord coming in contact with the steel...or may become energized by a lightning hit to the building. How about stray voltage that may be present in the earth seeking a path throught the concrete to the steel set upon it?
I hope you do not become an inspector in MA.
Forget about the pool example, the bonding in a pool area has little to due with keeping the parts from being energized. It has to due with keeping the parts at the same potential. There is a difference.
680.26 Bonding.
(A) Performance. The bonding required by this section shall be installed to eliminate voltage gradients in the pool area as prescribed.
Here is some info on that from the handbook following 680.26
The primary purpose of bonding is to ensure that voltage gradients in the pool area are eliminated. The fine print note explains that the 8 AWG conductor's only function is to eliminate the voltage gradient in the pool area. It is not required to provide a path for fault current that may occur as a result of electrical equipment failure.
Exposed structural steel that is interconnected to form a steel building frame to me means a building that has a steel skeleton not a wood building that has an occasional steel member.
To each there own, I would fight it if it was a cost issue.
We work in some old mill buildings that are made of brick and wood, in many places the horizontal timbers have been 'sistered' with steel channels. I would not accept an inspector telling me I have to bond all of these with a separate pieces of steel on the upper floors back to the service with a conductor based on 250.66.
JMO, Bob
