Building Steel ?.

[goldstar]

We recently upgraded to a 200 amp service in a building that is going to be a gymnasium. Many years ago it was a movie theater. We were not able to drive ground rods outside due to the sidewalks coming right up against the building as well as the parking area blacktop. We ended up driving both ground rods through the wall under the breaker panel and, in essence, in contact with the earth under the sidewalk. There is a gas service but no water service (at least at this point in time) to this building. My question is : Are we required to bond the electric service to the building steel ? The only available/exposed steel is about 25' up and is supporting the roof. We will be hanging about 25 LED light fixtures, and a few paddle fans from this structure.

Thanks in advance.

 

[Dennis Alwon]

IMO, the steel needs to be bonded and may very well be an electrode- 250.104(C).

This building was a movie theater and had no water??? That makes no sense. If the water line is defunct but is in the building and has 10' of metal piping in the ground then IMO, it also needs to get used as a grounding electrode.

BTW, I have drilled the concrete and drove rods.

 

[augie47]

Slightly different view than Dennis.....
I would need to more more about the "steel".. Is waht you see part of the steel framework of the building and only the ceiling portion is exposed or is the steel you see simply metal trusses on block walls ?
If there is a metal frame then you need to attach to it even if you need to do so 25 ft up.

 

[kwired]

I also agree that steel needs to be bonded, but need more details before we can determine if it is a grounding electrode.

 

[goldstar]

IMO, the steel needs to be bonded and may very well be an electrode- 250.104(C).

This building was a movie theater and had no water??? That makes no sense. If the water line is defunct but is in the building and has 10' of metal piping in the ground then IMO, it also needs to get used as a grounding electrode.

It makes no sense to me either but there was none that we could find (at least at this point). That's not to say that this might not change in the future The entire inside is gutted

BTW, I have drilled the concrete and drove rods.

The original rod was a piece of 3/4' GAL in the concrete pour. I don't think it was driven after the fact. We tried 2 different hammer drills including a Hilti. Couldn't get through so we decided to go through the wall and under the sidewalk.

 

[goldstar]

Slightly different view than Dennis.....
I would need to more more about the "steel".. Is what you see part of the steel framework of the building and only the ceiling portion is exposed or is the steel you see simply metal trusses on block walls ?

That's exactly what we have, trusses on top of what appears to be pilasters (for lack of a better description).

If there is a metal frame then you need to attach to it even if you need to do so 25 ft up.

I tend to agree with you and I'm not about to chip away at the brick surrounding what may be steel inside the pilaster in order to bond to it.

BTW, this all started as a disagreement with my partner (a fellow EC on this project). My position was always that it had to be bonded and his was that it was not required. I think the EI would fail this if it is not bonded IMHO.

 

[goldstar]

I also agree that steel needs to be bonded, but need more details before we can determine if it is a grounding electrode.

What kind of details are you looking for? I'll probably be back there sometime this week and I'll try to get that and post it here.

 

[kwired]

What kind of details are you looking for? I'll probably be back there sometime this week and I'll try to get that and post it here.

250.52(A)(2) tells us what is required to call structural steel a grounding electrode.

250.104(C) tells us we need to bond structural metal (that isn't otherwise bonded because it is required by 250.52(A)(2)) but does contain the words "is likely to become energized".

So if this steel is in the roof system and there is no wiring in that roof system area or attached to it - it isn't likely to become energized and 250.104 doesn't need to apply and if it isn't attached to other steel that qualifies it as a grounding electrode - you shouldn't need to bond to it at all.

If it is not a qualifying electrode, bonding to it doesn't help with meeting grounding electrode system requirements.

 

[Dennis Alwon]

What kind of details are you looking for? I'll probably be back there sometime this week and I'll try to get that and post it here.

I think kwired was saying in order for it to be a part of the grounding electrode system then it would have to be in contact with the earth as described in 250.52(A)(2)

 

[petersonra]

It seems to me that unless the steel qualifies as a GE, bonding it is probably pointless. The code only requires it if it is "likely to become energized", and whatever metal there is surrounding whatever source of electricity might energize it is probably already effectively bonded to the steel.

 

[electricalist]

I would bond the roof steel if you re going to be hanging 25 lights, and the wiring method is supported by the steel so when the inspector came it was apparent I did what I could to meet the GES requirements.
Bonding that far up is typical as well as driving rods through a slab.

 

[Dennis Alwon]

It seems to me that unless the steel qualifies as a GE, bonding it is probably pointless. The code only requires it if it is "likely to become energized", and whatever metal there is surrounding whatever source of electricity might energize it is probably already effectively bonded to the steel.

That is the key- likely to be energized... but who knows what an ahj will require. Likely to be energized is not defined.

 

[kwired]

I would bond the roof steel if you re going to be hanging 25 lights, and the wiring method is supported by the steel so when the inspector came it was apparent I did what I could to meet the GES requirements.
Bonding that far up is typical as well as driving rods through a slab.

Again - if that steel is not interconnected to other steel that is in contact with earth (or encased in concrete in earth) for at least 10 feet - you don't have a grounding electrode and do not need a grounding electrode conductor run to it. However even if it is isolated from earth, 250.104(C) as mentioned before does still require other structural metal to be bonded if likely to become energized. Mounting/supporting electrical equipment from it certainly increases that chance it may be energized I would think.

Where you maybe run into not needing to bond structural steel the most is in wood framing for a floor but they maybe use a steel beam to span an open area below. That beam in that situation does not normally have electric equipment attached to it, is not likely to become energized, and is also isolated from anything with continuity to earth.

I do see more engineered wood beams in more recent years in places where you used to see steel beams though.

 

[electricalist]

I'd think there is structural steel somewhere there that the roof is attached too. Typically every 40' I usually see some type of support beam. But I agree that it's not required if it doesn't qualify. If you're already up there putting up the lights 200 amp ground won't be that much too much.

 

[goldstar]

The code only requires it if it is "likely to become energized", and whatever metal there is surrounding whatever source of electricity might energize it is probably already effectively bonded to the steel.

I see your point but the term "Likely to become energized" I think is a matter of opinion. Unfortunately in this case, the AHJ will be the opinion that counts. If we are running 3/4" EMT up to and attaching to the roof steel structure for the lighting circuit, the conduit run starts at the breaker panel and is grounded there. What is the likelihood that the trusses can become energized through that conduit ?

I will not know until we rent the scissor lift whether the roof truss steel is actually connected to steel inside the pilasters. I will post when I find out.

 

[electricalist]

I think the EG and the GES should be 1 in the same if properly bonded,,not by a bang on..... But I'm no ahj

 

[goldstar]

I think the EG and the GES should be able to be the conduit if properly bonded,,not by a bang on..... But I'm no ahj

We're more than likely going to be using bang-on Caddy clamps. Not sure if that make a difference.

 

[electricalist]

You're good with what your doing. My comment was in explained.Sorry. I had been looking up why a conduit couldn't be an electrode as well as an e.g. ...like in your situation if the steel qualifies as an electrode and the emt is your ground then why not properly bond one to the other and it be ok. Although not likely since if the emt get removed so does the GES .

 

[kwired]

I'd think there is structural steel somewhere there that the roof is attached too. Typically every 40' I usually see some type of support beam. But I agree that it's not required if it doesn't qualify. If you're already up there putting up the lights 200 amp ground won't be that much too much.

Newer construction is likely, 100 year old building may have a lot of bricks or blocks with no continuous steel down to grade as support under those steel framing members for the roof - those would not necessarily be grounded - as in a qualifying electrode.

 

[Dennis Alwon]

Imo if you cannot determine if the steel is an electrode then I would be safe and bond it