ECN Forum Forums Code Related Discussion NEC & other Code issues Bonding of metal siding

Got asked today; 'How many #12 THHN in 1"'

My answer: "How many guys pulling?"

That's an easy one. ALL OF THEM!

I am with Reno on this one. The only time I would even thing about bonding it my self or requiring others to bound would be if it were likely to become energize like from a badly located service drop only because a service drop is not grounded on the secondary side. I am curious about how many cases of siding getting hit directly by lightning and surviving the strike, not to mention someone touching it at the monent of the strike.

Soares Book on Grounding & Bonding 9th Edition.
Thoses of you who have it read Pages 145/146.
Page 166. Theres even pictures .
The bible of Grounding & Bonding.
Yoopersup

The Soares book just shows the structural steel frame as it says in 250.104[C] in the NEC.
As I was saying, I don’t see the exterior metal sheathing included in this requirement, but it usually ends up bonded to the frame through the screws used to fasten it in place.

Apparently though, some states AHJ’s interpret this requirement to include the exterior sheathing as part of the structural steel the building frame, so want some other form of intentional bonding jumper attached to it. Seems redundant to me, but I guess it couldn't hurt to do it.

I can see it now ... a shiny band of copper plumbers' tape, affixed all around the building at roof line, held on with sheet metal screws.

Less enticing is the thought of doing all that from a 26 ft. ladder, on uneven ground, resting against smooth steel walls, whose indentations are not quite right to catch the ladder. All in the name of 'safety,' of course.

That’s another reason why I don’t believe that metal sheathing was intended to be included in the requirements of 250.104[C].
If the building had 750 kcmil CU service conductors, according to Table 250.66, you would need to bond the metal sheathing with a minimum 2/0 CU conductor.
I'm just wondering where and how would the lug for the 2/0 conductor get securely attached to the thin metal sheathing used on steel buildings?

Ever hear of a Pole Building ??? Wooden frame all metal sheating.
A lot of theses buildings have Electrical panels , with outlets, lights, welding outlets ect.
To me if a building has Metal frame & metal sheating screwed to & the frame is bonded its bonded. But what if like a Pole building the sheating is not bonded? What about steel beams in houses the romext is layed in them ??
Instead of sly comments lets try to be constructive here
Yoopersup

The steel beam with romex next to it was the specific reason the 'likely to be energized' reason was included! It was specifically so some idiot would not demand it be bonded.

I clearly remember that debate, long ago. Those who are trying to confuse the matter are dishonestly trying to reopen a debate that was decided more than 40 years ago.

Ditto for the steel roof, aluminum siding, and every other variation. I does not need any special effort be nade to bond it.

The honest way to approach this is to propose a change, deleting that phrase - rather than trying to parse around it.

I have seen inspectors require the steel I-beam between the 2 garage doors be bonded. They said it could become energized and failed the EC when the beam wasn't bonded to the service. Even when the I-beam sat upon all wood construction.

I'm not surprised. Remember, I'm in Nevada - where folks also insist they've seen UFO's

We could go off on a tangent as to the foibles of inspectors - we all have such stories - but that would probably not enlighten anyone.

The key here is "likely to become energized." If you want to say that's a judgement call, I won't argue; it is. The far side of the moon 'might' become energized 'if' some things happen. Let's look at the 'likely' part.

To use your garage door example, I can't picture any fault that would energize the beam without first energizing the door, the conduit, the case of the opener - and that's where there would already be a bond. If you're not already bonding it at the appliance, you have a problem.