Continuous GEC

[Rich Elec.]

I have a question concerning 250.64(C). Continuous GEC no splice unless... 1-4. On #3 "Connections shall be made by a listed connector or by the exothermic welding process." I would like some solid information on what is considered a listed connector. I have seen split bolts, and barrel lugs used.

I also wonder about terminationg EGC's with a mechanical lug bolted to a beam clamp and then clamped onto a steel beam. This would be for something like cable tray.

 

[rcarroll]

I would consider a listed connector as being irreversible. Like a crimp type butt splice.

 

[raider1]

On #3 "Connections shall be made by a listed connector or by the exothermic welding process." I would like some solid information on what is considered a listed connector. I have seen split bolts, and barrel lugs used.

250.64(C)(3) is talking about bonding jumper(s) from grounding electrode(s) and grounding electrode conductor(s) being permitted to be connected to a copper bus bar using connections made by a listed connector or by exothermic welding process.

If you are wondering about splicing a GEC with a split bolt or barrel lug, then look at 250.64(C)(1) which states that splicing shall permitted only by irreversible compression-type connectors listed as grounding and bonding equipment or by exothermic welding process.

Hope this helps,

Chris

 

[Rich Elec.]

Thanks Chris,
That proves that the split bolt is illegal.
How about the EGC, lug, beam clamp, to building steel.
Legal?
Effective?

 

[benaround]

Rich,

The beam clamp is not " listed for grounding and bonding equipment" as

pointed out by the art. Chris presented.

 

[raider1]

Thanks Chris,
That proves that the split bolt is illegal.
How about the EGC, lug, beam clamp, to building steel.
Legal?
Effective?

Your welcome.

As far as the EGC connected to the building steel, could you explain what EGC you are talking about? You said like in a cable tray. A cable tray can be used as an EGC take a look at 392.3(C) and 392.7. Maybe if you clarify what you are asking I could give you a better answer.

Chris

 

[Rich Elec.]

Chris,
I was thinking of cable tray listed as not being capable of being used as a eqip. ground.
But I think that the question I meant to ask is: Is a beam clamp listed for grounding and bonding equipment.
As benaround stated.
I had guessed that the beam clamp is not listed as such, but I would like a little more info. or a reference so that I can prove my case on the job.

 

[raider1]

I had guessed that the beam clamp is not listed as such, but I would like a little more info. or a reference so that I can prove my case on the job.

The connection of a GEC to an electrode (in this case building steel) shall be connected by exothermic welding, listed lugs, listed pressure connectors, listed clamps, or by other listed means. (Take a look at 250.70)

You can't use building steel as an EGC. Take a look at 250.134 for the requierments for grounding equipment fastened in place or connected by permanent wiring methods. Also take a look at 250.118 for the types of equipment grounding conductors.

Chris

 

[Rich Elec.]

GREAT CHRIS!
This helps, but I am thinking that I wasn't clear on my question.
Cable tray, insulated copper stranded wire run from the cable tray to a mech. lug which is bolted to a beam clamp which is clamped to building steel.
250.70(2) "A lited bolted clamp of cast bronze or brass. or plain or malleable iron."
What so you think?
On you second paragraph I need to do some more reading. You can't use building steel as an EGC. I'll get back to you on this.

 

[raider1]

On you second paragraph I need to do some more reading. You can't use building steel as an EGC. I'll get back to you on this.

Take a look at 250.136(A).

The last sentence of that section states:

"The structural metal frame of a building shall not be used as the required equipment grounding conductor for ac equipment."

Hope this helps.

Chris

 

[Rich Elec.]

250.136(A).
How about 250.130(C).
EGC...shall be permitted to be connected to any of the following: #1.
Any point on the grounding electrode system as described in 250.50.
250.50 sends you to 250.52.
250.52 (2) Metal frame of the building or structure.

Now I know that this is for a receptacle and my question was regarding cable tray, but this has a different standard than 250.136(A) (which is for equipment on a metal rack.)
So I wouldn't automatically say that building steel cannot be used as an EGC.

And with 250.70(2). I am thinking that a malleable iron beam clamp is acceptable for grounding.

 

[raider1]

So I wouldn't automatically say that building steel cannot be used as an EGC.

Within the context of our discussion, there was no mention of a non-grounded receptacle replacement or branch circuit extention, so therefore I did not reference this section because it was not relevant. As a general rule you can't use building steel as an equipment grounding conductor (See 250.136(A))

I am thinking that a malleable iron beam clamp is acceptable for grounding.

Within the context of 250.70 a malleable iron bolted clamp must be listed for grounding.

Chris

 

[Rich Elec.]

Thanks for the help Chris.

Rich.

 

[raider1]

You are very welcome Rich.

Chris

 

[Psychojohn]

What does the Nec consider exothermic welding to be?

 

[iwire]

What does the Nec consider exothermic welding to be?

In my area we call it Cad welding but that is really more of a brand name.

Here is what is usually needed.

You buy a mold that is specific to what you are joining and then add the proper charge size, light it off and stand back.

It's a great product but you need a different mold for every different wire size, ground rod size, vertical or horizontal steel etc.

Check this link for more info.

 

[Psychojohn]

Thank you, Not even the instructor at the last NEC seminar I went to was sure.

 

[Cody K]

in my case, would a metal frame skid (approximately 12ft by 25ft) that some 480v motors are mounted onto be considered a metal building or a metal rack? I have run into an application today that the installer used the skid itself for the EGC (bonded with 4 bolts to skid). Is that legal?