Building steel bonding

[User Name]

Hey guys.

Customer has a wood frame shop with a 400 amp service in it.

They added an all steel building on to it.

I ran a 200 amp subpanel to the new steel building.

Does the building steel get bonded to the 200 or 400 amp service?

 

[LarryFine]

Does the building steel get bonded to the 200 or 400 amp service?

Whichever is closer.

 

[User Name]

If I run it to the 200

Would I be sizing that under 250.66 as a GEC or

250.122 as a EGC?

 

[suemarkp]

Describe the building. Is it steel posts into the earth, or a metal building placed on and bolted down to a concrete slab?

I had an inspector want a metal pool pump shed bonded. How he thought it may become energized I don't know, but he wanted a conductor sized per 250.122 which was #10 copper in my case.

 

[User Name]

Describe the building. Is it steel posts into the earth, or a metal building placed on and bolted down to a concrete slab?

I had an inspector want a metal pool pump shed bonded. How he thought it may become energized I don't know, but he wanted a conductor sized per 250.122 which was #10 copper in my case.

It's a placed on concrete and bolted down type. I'm hoping it falls under 250.122, but my concern is that metal structure framing falls under 250.68 C 2 as a GEC. Which could really screw me up.

 

[hillbilly1]

Building steel no longer qualifies as a grounding electrode unless it is bonded to the ufer, so the sub panel egc bonds it.

 

[petersonra]

Building steel no longer qualifies as a grounding electrode unless it is bonded to the ufer, so the sub panel egc bonds it.

It is not a grounding electrode. It can be a bonding means to the grounding electrode.

 

[hillbilly1]

It is not a grounding electrode. It can be a bonding means to the grounding electrode.

Thought that was what I said?

 

[RdmanElect]

If this building is a separate building and you're bringing a feeder to it, it requires a separate grounding electrode such as a ground rod, in that case you can bond the building steel and ground rod to your 200A panel. Check out 250.32

Sent from my Pixel 7 using Tapatalk

 

[don_resqcapt19]

It's a placed on concrete and bolted down type. I'm hoping it falls under 250.122, but my concern is that metal structure framing falls under 250.68 C 2 as a GEC. Which could really screw me up.

it doesn't matter the bonding conductor is sized per Table 250.102(C)(1). However that bonding is only required if the steel structure is likely to become energized. See 250.104(C). Note the permitted connection points in 250.104(C)(1) through (5).

 

[User Name]

it doesn't matter the bonding conductor is sized per Table 250.102(C)(1). However that bonding is only required if the steel structure is likely to become energized. See 250.104(C). Note the permitted connection points in 250.104(C)(1) through (5).

Got it. So for my subpanel I ran 4/0 AL with a 4 AL ground, which is fine, for this situation I need to bond to the building steel using 2 AL (would probably do 4 copper though) but just to compare to my EGC...do I need to replace my 4 AL because its not as big as a bonding jumper?

 

[don_resqcapt19]

Got it. So for my subpanel I ran 4/0 AL with a 4 AL ground, which is fine, for this situation I need to bond to the building steel using 2 AL (would probably do 4 copper though) but just to compare to my EGC...do I need to replace my 4 AL because its not as big as a bonding jumper?

The way I read it, the bonding conductor to the steel is based on the size of the service entrance conductors.