At what point do we consider the need to bond structural steel. Does a steel I Beam supported by steel post setting on concrete need to be bonded?

It needs to be bonded if it might become energized.

It should not take long to do and should not cost much. So there is little reason to not do it.

Okay George, with a name like that, I know you know what your talking about At what point is it likely to be energized? Does the steel beam in a basement of a home need to be bonded??

[This message has been edited by George Little (edited 02-12-2005).]

A single column supporting a beam is not a steel building frame and the code does not require bonding.
Don

Don- I agree with you but we have inspectors out there that are asking that this steel be bonded and I just wonder where they are coming from???

George Little ---

"may become energized" is the rub. If you lay cables or conduit over or along the steel beam, I would lean toward "may". If no cables or conduit run over or along the beam, I would lean toward "may" not.

I don't see enough support in the code to support your position in an appeal.

George,
Just the fact that isolated steel may become energized does not trigger the requirement for bonding. The bonding requires both the possibility that the steel may become energized and that the steel be an interconnected building frame
Don

resqcapt19 ---

I believe that wall switches are bonded because the tiny metal screw in the plastic plate might become energized, provides reasonable support for my position.

If I were inspecting and found this isue, I would point out the need and let the contractor do what he will.

George you are worrying me now, are you the type of inspector that makes the rules up as you go along?

Don already went over this I will try to make it clearer.

2002 NEC

In order for you to be able to require any electrician to bond steel it has to meet all of the following.

It must be exposed

AND

It has to form the steel frame of the structure.

AND

It has to be likely to be energized.

The opening post asked this;


If that is the extent of the steel you have no authority to ask for it to be bonded.

I do not take the term "may become energized" to be all encompassing.

In my opinion you would have to show a way or reason it may become energized.


You do require conduit to be grounded and you do require proper supports for cable systems right?

So how would this lonely piece of steel become energized?

Bob





[This message has been edited by iwire (edited 02-13-2005).]

I tend to side with Bob on this one. "May become enrgized" could open up a can of worms similar to what we do at a swimming pool. We could be bonding handrails, doors and shelving if we are looking at everyone who is not careful with their Christmas lights and cell phone chargers. If there is electrical utilization equipment hanging on that beam I would want to see the EGC bonded to the beam (the EGC of the circuit likely to energize... yada yada) but if this is a properly supported and routed wiring method simply passing near the beam, I don't see the problem.

I hope you guys are aware that there are two Georges on this page and I (George Little) agree with Don. I'm not sure about George #2

Yeah, I almost said 'George not little'

IMO...parts of 250.104(C) are vague and open to interpretation by the AHJ.

For instance,"may become energized"...could mean a number of different things to me. 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? We are concerned with this stray voltage around pools,wouldn't this structural building steel in George Little's 1st post be exposed to stray voltage from maybe, deteriorating utility neutral conductors in the area like a pool would? Probably not as much as a pool but there is a possibility that it May Become Energized.

250.104(C) also doesn't state how much steel has to be interconnected to form a building frame.Is it a complete frame structure or a couple of pieces of steel forming a partial structure as in George Little's post? The definition of structure in article 100 is "That which is built or constructed"... so those 2 pieces of steel seem to be a structure to me.

Yes...I think it is open to interpretation by the AHJ...IMO

shortcircuit

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.


Here is some info on that from the handbook following 680.26


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

Yes bonding of a pool primary fuction is to eliminate voltage gradients that may be present. But it also brings the structure of the pool and all associated equipment to the same potential in case something were to become energized. Bonding of a pool and bonding of a buildings structural steel are alike...there are both keeping parts of a steel structure and electrical equipment at the same potential in case they do become energized.

Isolated sections of steel on the upper floors as you have described in the old mill are different than the structual steel setting on concrete in direct contact with the earth as I assume is the exsample in George Little's post.

If 250.104(C) intended to mean a complete steel skeleton forming the structual steel of a building need only be bonded...then it should say just that. But it can not. Surely someone would hang if somebody were to be hurt coming in contact with George Little's steel structure that was energized and not properly bonded because 250.104(C) only meant to bond complete steel structures forming the skeleton of a building.

My opinions are based on what I've been taught by instructors. This forum is a place to voice opinions of how things are done in the industry and interpretations of the codes applied to them. If I am wrong about something, then please correct me. I am here to learn.I don't see the need for the inspector comment...

JMO, shortcircuit

I disagree, the section in question 250.104 is not all about keeping everything the same potential, that section is there to cause an overcurrent device to operate if the steel becomes energized by a circuit conductor.

The bonding at a pool is there to keep all things that you can come in contact with at the same potential even during a fault condition when that bonding system has a potential above earth.

Isolated sections of structural steel are not a pool, a pool is different, pools have different bonding requirements because they are....well..different.

I mean no disrespect here but I have no idea why you think that "structural steel setting on concrete in direct contact with the earth" in of itself is dangerous.

If thats so should I bond my child's swing set?

What about a metal folding chair sitting on a concrete slab?


Please explain how this isolated piece of steel would be affected by a bad utility neutral.



There is no path until you bond it.

Current does not flow without a complete circuit.

I would take back the inspector comment but statements like this;


Leads me to believe you have a serious misunderstanding of this section.

If we accept your extension cord scenario the next question would have to be why limit bonding to isolated sections of structural steel, why not require all metal objects in a building to be bonded?

File cabinets, suspended ceiling grids etc.

At any rate we have certainly proved George Littles point.

I feel I should say my opinions are my own and not those of ECN.

All are welcome to disagree.

Bob



[This message has been edited by iwire (edited 02-13-2005).]

The bonding of structural steel has become an issue in our area as well. I think the wording could be worked with for clarity.

1. It does not say the frame of an entire building. I have seen (especially in residential) portions of the framing to be ofmetal and portions to be of wood.
I think the 2 keys here are "may become energized" and "Exposed Structural steel", not one or the other, but both items have to be present at the same time.
In the residential buildings I mentioned, most of the time the steel is concealed at final construction, so it becomes a moot question. Otherwise how would one make the connection "accessible"

This is a little off base on a tangent of bonding structural steel, but in one jurisdiction that I worked in, I had to bond the aluminum siding of a house with #6 copper and a lug bolted to the siding. Seems it was a local law that was passed after a town councilman's daughter got shocked by some stray current from an outside light.

I am concerned about(exposed)structural steel setting concrete in contact with the earth because it establishes a Ground-Fault Current Path.

250.2 Definition..."Ground-Fault Current Path"...
An electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors,equipment,or the EARTH to the electrical supply source.

FPN:Exsamples of ground-fault paths could consist of any combination of equipment grounding conductors, metalic raceways, metallic cable sheaths, electrical equipment, and any other electrically conductive material such as metal water and gas piping, STEEL FRAMING MEMBERS, stucco mesh, metal ducting, reinforcing steel, shields of communications cables, and the EARTH itself.

Surely George Little's steel framing would have to be evaluated by the AHJ to see if it were to present a hazard.

Concrete floors in contact with the earth do establish a path through the earth to the supply source. We GFCI most 15 and 20 amp receptical outlets in these areas because of this.

Article 100 Definition of "Bonding"...

The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to carry ANY current likely to be imposed.

There is only one definition of bonding...not one for swimming pools and one for everything else.

shortcircuit

A column and a beam is not "exposed structural steel that is interconnected to form a steel building frame" and therefore the code does not require bonding.
CMP 5 made the following panel statement in comment 5-111 in the 95ROC.
The words "single family dwelling" were used only in response to the submitters words in his comment. It is my opinion that isolated supports like these in any occupancy are not required to be bonded as the are not a "steel building frame".
Don

[This message has been edited by resqcapt19 (edited 02-14-2005).]

I am confused as to how this can be so confusing. It is clearly stated in plain english "....interconnected to form a steel building frame" How the heck can some one say a single steel beam under a house is anything close to that? To me there is not even interpretation needed as this is clear as can be. The '05 changes the wording somewhat to make it even clearer. It uses the word "metal" building frame. No big deal there. BUT it changes "May become energized" to "LIKELY to become energized". In my view if the steel is "likely" to become energized somebody screwed up bigtime.

It does say that.

Now you are spinning. "Interconnected to form a steel building frame" Where do you see the word "Structure"? You added that. A couple of pieces of steel for support do not "Form a steel building frame" .

Another point on Bob's "inspector" comment. I tend to agree with what he said. I too would fight this if an inspector told me I would have to bond a beam in this situation. As I wrote in another topic there are those that believe that the NEC says you have to bond any and all metal period. It does not. As I stated I was at a grounding and bonding class where the "Instructor" (term used lightly) pointed out that single steel support beams, lally columns, oil tanks, one foot sections of copper pipe stubbed out to bathroom fixtures from plastic pipping systems etc must be bonded. Pretty obvious as to why there is so much confusion. People tend to take everything they hear as gospel. I don't.

Sorry about the swimming pool FUD, I was just referring to what can result from bonding paranoia.
I still like the concept of bonding metal to the EGC of the circuit likely to energize the metal in question. If your 1 foot of isolated metal pipe serves an instant water heater I would want to be sure the EGC of the heater was effectively bonded to the pipe.

Different bonding requirements but I would say we are not required to bond that either.

1' of copper pipe does not constitute a metal piping 'system'.

This is much like the above argument about the steel building frame.



I can see no way we can call a isolated 1' piece of copper tubbing a 'system'.

By the way if you do apply the bonding to this isolated piece of pipe the conductor would need to be sized per table 250.66 not 250.122 so the EGC of the heater is not acceptable.

This IMO makes the thought of bonding small pieces of pipe even more ridiculous.

Bob

This thread has entered the Bizarro world. This I'd love to see. What about the metal towel bar under the sink that sits right next to this instant hot water dispenser or the spout that sticks out of the counter to dispense the hot water. Imagine all the runs of #4 cu running all over the house.

[This message has been edited by Electricmanscott (edited 02-14-2005).]

If that towel bar was heated it should be bonded, as they are, via the EGC of the circuit likely to energize it (the 3d prong on the plug). The same should be true of any plumbing going to an "insta'hot".
I certainly agree with those who say you don't need to bond every scrap of isolated pipe or other metal. Only those likely to be energized by attached equipment.
If we get back to the beam, I would only be oncerned if it had equipment hanging from it and I would want it bonded to that equipment's EGC. Incidental contact with cables running nearby should be handled with the securing and physical damage articles.

Same problem as the instahot, if we try to apply the bonding requirements of 250.104 the EGC is not enough.

Both those sections require a 250.66 sized bonding conductor.

As Scott mentions that will be 4 AWG copper for a house with a 200 amp service.

The equipment mounted to the beam or the instahot connected to that 1' piece of copper tubing cannot energize either if they are installed per code with proper EGCs.

I would tend to believe what the CMP-5 was refering to was a single steel beam with support posts of wood...which is often installed in a single family dwelling.

If George Little's steel I beam supported by a steel post set on concrete in contact with the earth were to be exposed to a ground fault and it wasn't bonded according to 250.104(C)...there would not be a low-impedance path to carry the ground fault current, which would not allow the over current device to open.This steel beam would be live.

In a industrial or commercial enviroment, this steel may not be likely to become energized, for hopefully only qualified personal would be installing wiring apparatus nearby.

But in the residential world it may be likely to become energized by some of the wiring I have seen by DIY homeowners.I just had to clean up a basement with extension cords running everywhere and the guy had adaptors in his keyless with 2-wire lamp cords strung all over the place, wrapped around gas piping and strung over metal duct work.

I still believe after all that has been debated here that George Little's (exposed) steel would have to be evaluated by the AHJ to see if it were to present a hazard.

As for the wording change to 250.104(C) from "steel" to "metal"...I think that this wording change adds a whole new list of bonding requirements.

Metal: any of class of elementry substances that are good conductors of electricity.

Steel: a hard,tough alloy of iron with carbon.

You see, the word METAL does't just limit bonding to steel.

Structure...the first sentence of 250.104(C) mentions exposed STRUCTURAL steel. (2002 NEC)

As far as some of the other equipment mentioned here such as the instant hot water or the heated towel bar...those pieces of equipment must be grounded(not bonded) according to 250.134 or 250.138

shortcircuit

I haven't seen a wood support post installed in the past 25 years.
Don

George,since we all seem to agree isolated sections of pipe are not the "metal water piping system" I would look at 250.104(B). That is more appropriate if you can make the case that they may become energized. Actually I bet the Insta'hot does ground the hubs where the pipes screw in, via the EGC.
I even have the compressed air piping in my garage bonded. My guess was that it would probably be a 20a circuit that "may" energize it but I went with a #8 anyway.

ShortC

If you want to bond every metal item in a building go ahead.

An inspector can not, under the NEC force it to be done.

I give up. This is ridiculous. Wood posts. Now you're really reaching. Good god. PLEASE post some pictures of your work. I have to see all this bonding.

[This message has been edited by Electricmanscott (edited 02-15-2005).]

This is kind of fun to see that not only in the area I work in, but all over confusion is apparent.
In regards to inspections, only the minumum can be enforced. Any additional work that is beyond the code and still compliant is fine.


Bob, I took some pictures of different types of structural metal that I would like to post for discussion of this topic. How do I get them here, or to you so they can be posted?
I have dialup - could I send you a disk with the pics?

Pierre

250.52(A)(2) of the 2005 NEC has been revised to add language to clarify criteria for determining grounding (and bonding?) of the metal frame of a structure or building.

I have a copy of the analysis of the change, but can't scan and post it. Maybe one of the moderators can help?

shortcircuit

Shortcircuit, 250.52(A)(2) has absoulutely nothing to do with what we are discussing here. That tells you the conditions that have to be met to use building steel as a grounding electrode conductor.

electricmanscott...I must admit that my interpretations of bonding of structural steel were out of line with the intent of the NEC. I also DO have a misunderstanding of parts of section 250...but, I bet 6 out of 10 electricians also struggle with understanding grounding. When taking code classes we are taught how to apply the code rules and most of the time not why we have to bond structural steel for instance.

In my 1st post on this issue I said that parts of 250.104(C)are "vague" and I attribute this to the code language.

In my last post I mentioned the change to 250.52(A)(2) language which does bring some clarity to me of the intent of the NEC when applying article 250 to structural metal of a building.

In class I used to sit and just listen. Now I ask questions so as to try to have a better understanding of why we do what we do.

ECN is a valueable resource and I want to thank all who respond to my(sometimes thickheaded) posts.

shortcircuit

ShortC

I agree 250 is a lot to digest, I have learned a lot myself from ECN and other forums.

Bob

They say the only stupid question is the one not asked. I have asked a stupid question or two so I know that is not true. Anyway hopefully everyone who reads this stuff gets something out of it. I know I do. Group hug!

BACK OFF JACK!

I too have heard of AHJ's asking EC's to bond the lonely piece of steel in a basement but I feel like some here that it is not required and I would never ask anyone to bond that piece of steel. Could it become energized? Well yea, I guess it could, however there is already a grounding conductor run with the cable (BX or RX)and that should be enough. Also the NEC is a mininmum and if you want to bond that I-beam you can do it.