Building Steel ?.

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goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
OK. Here is what I have on this job. From what I can determine the steel structure is resting on the pilaster. It looks as though the iron workers inserted threaded rod into the pilaster, installed a bed of concrete, smoothed it over and bolted the steel framework onto the threaded rod. To be safe I'm thinking we'll need to bond the service to it. Does anyone disagree ? Thanks.



 

kwired

Electron manager
Location
NE Nebraska
OK. Here is what I have on this job. From what I can determine the steel structure is resting on the pilaster. It looks as though the iron workers inserted threaded rod into the pilaster, installed a bed of concrete, smoothed it over and bolted the steel framework onto the threaded rod. To be safe I'm thinking we'll need to bond the service to it. Does anyone disagree ? Thanks.



Probably is easier or less cost then trying to measure resistance of the elecrode (if there is one). But if there is equipment "likely to energize" the steel you need to bond it anyway. But older construction like that likely does not have steel in the column that ties into anything that makes it an elecrode. If it were newer poured concrete column with reinforcing steel in it - the chance of it being an qualifying electrode increases. If anything it may be tied to a CEE in a footing at very least - but IMO you only have a CEE and not a building steel electrode in that case, and one GEC is suitable for both the CEE and bonding the steel should it be subject to becoming enerized - unless it can be energized by a circuit that needs larger then a 4 AWG EGC.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
"Likely to become energized" is a term subject to interpretation. In this case we are hanging (24) LED light fixtures, (4) paddle fans, wiring (3) motor driven gas heaters at roof level and several duplex receptacles coming down on the columns. All are connected (and in contact with the steel) via EMT. The chances of the roof steel becoming energized is a shot in a million IMHO. We'll be bonding the service to it anyway. If the EI tells us to remove it, so be it. Thanks.
 

kwired

Electron manager
Location
NE Nebraska
"Likely to become energized" is a term subject to interpretation. In this case we are hanging (24) LED light fixtures, (4) paddle fans, wiring (3) motor driven gas heaters at roof level and several duplex receptacles coming down on the columns. All are connected (and in contact with the steel) via EMT. The chances of the roof steel becoming energized is a shot in a million IMHO. We'll be bonding the service to it anyway. If the EI tells us to remove it, so be it. Thanks.
I agree, but I believe I mentioned earlier that it is not so likely to become energized in a situaiton where those steel trusses have a ceiling below them and no wiring is installed in the attic space - in that situation I would take a firm stand against any inspector that tries to tell me they are likely to become energized, but if steel raceways are attached to those steel framing members it is much more difficult to make a claim they will or will not become energized. If they do become energized so does the steel raceway, which really can happen when you have lost neutral on the service conductors event.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
This is just a report on the grounding issue. At present this building has no water service (was probably disconnected many years ago I'm guessing). We were not able to drive ground rods through the concrete floor so we decided to drive the rods thru the wall and 12" below the sidewalk outside. EI failed the job claiming that the rods have to come in contact with at least 3' of soil. I believe he is not correct on this but he did not site a Code section. I live in a mountainous area and from my own experience I never drive rods straight down. They are always driven on a SEVERE angle. Never failed an inspection for that.

Anyway, my partner on this job is having a portion of the floor excavated in order to drive new rods. My thinking is to excavate a narrow 8' length of concrete floor, lay the rod long ways, install a re-bar clamp and wire and pour cement back over it. Would that be considered a CEE ? BTW, gas meter is being installed and water service is on its way in the near future. We will bond to the water line when it's installed. There was no mention to bond to the building steel.
 

kwired

Electron manager
Location
NE Nebraska
This is just a report on the grounding issue. At present this building has no water service (was probably disconnected many years ago I'm guessing). We were not able to drive ground rods through the concrete floor so we decided to drive the rods thru the wall and 12" below the sidewalk outside. EI failed the job claiming that the rods have to come in contact with at least 3' of soil. I believe he is not correct on this but he did not site a Code section. I live in a mountainous area and from my own experience I never drive rods straight down. They are always driven on a SEVERE angle. Never failed an inspection for that.

Anyway, my partner on this job is having a portion of the floor excavated in order to drive new rods. My thinking is to excavate a narrow 8' length of concrete floor, lay the rod long ways, install a re-bar clamp and wire and pour cement back over it. Would that be considered a CEE ? BTW, gas meter is being installed and water service is on its way in the near future. We will bond to the water line when it's installed. There was no mention to bond to the building steel.

This reply is regarding the mentioned 3' of contact -

250.52(A)(5):
(5) Rod and Pipe Electrodes.
Rod and pipe electrodes shall not be less than 2.44 m (8 ft) in length and shall consist of the following materials.
Grounding electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size ¾) and, where of steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
Rod-type grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm (⅝ in.) in diameter, unless listed.

Doesn't really specify a minimum contact length, I think most people take it to mean that you must have at least 8 feet of contact though.
May want to look at listing requirements if using rods that are listed - they may have such a requirement.
 

sparkyrick

Senior Member
Location
Appleton, Wi
If the steel bar joists are resting on a block wall, with no other connection to the foundation, then they are not considered a grounding electrode.

If the steel bar joists are connected to structural steel, that connects to anchor bolts in the foundation, then it would qualify as a grounding electrode.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
This reply is regarding the mentioned 3' of contact -

250.52(A)(5):


Doesn't really specify a minimum contact length, I think most people take it to mean that you must have at least 8 feet of contact though.
May want to look at listing requirements if using rods that are listed - they may have such a requirement.
I don't know where he came up with 3' of contact but I remember being in a CEU class where a rep from the state specifically mentioned that it had to come in contact with the earth. That doesn't mean the rod has to be driven straight down but by the same token it also doesn't mean that you can lay the rod on the ground and throw some dirt on top of it. I partnered with another EC so it's his call as to whether he wants to call the state on this or just install a CEE. We'll see what happens.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
I don't know where he came up with 3' of contact but I remember being in a CEU class where a rep from the state specifically mentioned that it had to come in contact with the earth. That doesn't mean the rod has to be driven straight down but by the same token it also doesn't mean that you can lay the rod on the ground and throw some dirt on top of it. I partnered with another EC so it's his call as to whether he wants to call the state on this or just install a CEE. We'll see what happens.
I don't have any idea what the three feet of contact is about, all eight feet of the rod has to be in the earth, and yes you can lay the rod in a trench and throw dirt on top of it.

250.53 Grounding Electrode System Installation.....

(G) Rod and Pipe Electrodes. The electrode shall be in-
stalled such that at least 2.44 m (8 ft) of length is in contact
with the soil. It shall be driven to a depth of not less than
2.44 m (8 ft) except that, where rock bottom is encoun-
tered, the electrode shall be driven at an oblique angle not
to exceed 45 degrees from the vertical or, where rock bot-
tom is encountered at an angle up to 45 degrees, the elec-
trode shall be permitted to be buried in a trench that is at
least 750 mm (30 in.) deep. The upper end of the electrode
shall be flush with or below ground level unless the
aboveground end and the grounding electrode conductor
attachment are protected against physical damage as speci-
fied in 250.10.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I don't have any idea what the three feet of contact is about, all eight feet of the rod has to be in the earth, and yes you can lay the rod in a trench and throw dirt on top of it.
I wasn't thinking about a trench when I made that comment. I meant that you can't just lay a rod on the earth's surface and merely cover it up with a thin layer of dirt. I wasn't thinking "out of the box". In addition my comment about laying an 8' rod below the floor and covering it with cement isn't going to be considered a CEE either. According to 250.52(3)(1) it has to be 20' in length in order to be considered a CEE.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
...
In addition my comment about laying an 8' rod below the floor and covering it with cement isn't going to be considered a CEE either. According to 250.52(3)(1) it has to be 20' in length in order to be considered a CEE.
And it has to be in a footing rather than just the floor slab.
:)
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I also agree that steel needs to be bonded, but need more details before we can determine if it is a grounding electrode.

My understanding of the code leaves me wanting clarification of this statement. I agree that, if this steel is mechanically connected to other steel extending down and ultimately in direct contact with the earth it needs to be bonded as part of the grounding electrode system. It is the "if it isn't" scenario I want clarification on.

The steel must be bonded when it has a possibility of becoming energized. I most cases, with most wiring systems, this bonding is inherent in the wiring methods in my opinion. If I have a 20 amp circuit in a box mounted to the beam, and that box is installed properly then the beam is bonded adequately. You may not have meant it but I have found many lesser electricians who think they have to run a ground specifically to bond the beam.
 

USMC1302

Senior Member
Location
NW Indiana
From what is described, the rods driven through the wall is no different than laying the ground rod in the trench. Only issue is the 30" depth.
 

kwired

Electron manager
Location
NE Nebraska
I don't have any idea what the three feet of contact is about, all eight feet of the rod has to be in the earth, and yes you can lay the rod in a trench and throw dirt on top of it.

250.53 Grounding Electrode System Installation.....

(G) Rod and Pipe Electrodes. The electrode shall be in-
stalled such that at least 2.44 m (8 ft) of length is in contact
with the soil. It shall be driven to a depth of not less than
2.44 m (8 ft) except that, where rock bottom is encoun-
tered, the electrode shall be driven at an oblique angle not
to exceed 45 degrees from the vertical or, where rock bot-
tom is encountered at an angle up to 45 degrees, the elec-
trode shall be permitted to be buried in a trench that is at
least 750 mm (30 in.) deep. The upper end of the electrode
shall be flush with or below ground level unless the
aboveground end and the grounding electrode conductor
attachment are protected against physical damage as speci-
fied in 250.10.
There it is, I wasn't looking in the right place.

My understanding of the code leaves me wanting clarification of this statement. I agree that, if this steel is mechanically connected to other steel extending down and ultimately in direct contact with the earth it needs to be bonded as part of the grounding electrode system. It is the "if it isn't" scenario I want clarification on.

The steel must be bonded when it has a possibility of becoming energized. I most cases, with most wiring systems, this bonding is inherent in the wiring methods in my opinion. If I have a 20 amp circuit in a box mounted to the beam, and that box is installed properly then the beam is bonded adequately. You may not have meant it but I have found many lesser electricians who think they have to run a ground specifically to bond the beam.
I agree.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
IMO, even if the steel qualifies as a GE and is bonded to the rest of the GES, you can't rely on that as part of your fault current path, so you still have to have an EGC if there is a likelihood of the steel becoming energized, and that EGC has to be part of the circuit that has the potential to energize the steel.
 

iwire

Moderator
Staff member
Location
Massachusetts
IMO, even if the steel qualifies as a GE and is bonded to the rest of the GES, you can't rely on that as part of your fault current path, so you still have to have an EGC if there is a likelihood of the steel becoming energized, and that EGC has to be part of the circuit that has the potential to energize the steel.

I agree, as practical matter the roof structure will be grounded by the wiring connected to it.
 
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