ECN Forum Forums Code Related Discussion NEC & other Code issues EGC attachment

Paul,

I didn't say to violate the manufacturer's warranty. You must be thinking of another respondent.

Bob,

I hear this misconception all the time. There is not a single AHJ who has supreme power over every thing you do. There are many AHJs who each have some authority over what we do for a living.

In CT, each local town will have the local AHJ (building official), and the State has the State Building Inspector, who the local AHJ may have to answer to.

The NEC references the AHJ as the person, organization or office that has authority over the electrical installation, such power often being granted by legislative act. (Article 100, check out the FPN)

Every job has multiple AHJs. (Even in Mass.) We all answer to the fire marshal, the electrical inspector, the building official, the licensing inspector, the insurance company and the tax collector. All of these are authorities having jurisdiction over some aspect of our work, often overlapping.

Paul,
And that would not have happened to the threads for the 10-32 screws that bond the listed equipment grounding bus to the panel?
Don

Paul,
Given that transformer cases do not have manufacturer provided tapped holes to make the required bonding connection to the case, how do you make this connection?
Don

[This message has been edited by resqcapt19 (edited 11-20-2005).]

I just read this thread for the first time. If I was a novice, my mind would have been going back and forth (like watching a tennis match), as both sides offer good arguments - but the bottom line is I would be confused as much as amused.

With that being said, I will add my 2 cents , Please let me add to the confusion/amusement.

Yes when the factory punches the enclosure, the dimple has more metal, and the factory threads will have more threads for connection.(tested and listed with the enclosure)

Adding a lug to the enclosure is permitted, as long as following the installation instructions, as the NEC is a permissive document, and I do not see where it directs one not to add a lug. That being said, the paint as per 250.12 is required to be removed to provide for lower contact resistance. Threading a field punched hole in the enclosure will not provide enough threads, so a nut and bolt connection should be provided - of course with the proper torquing .

"300.6(A)... and support hardware shall be suitably protected against corrosion inside and outside (except threads at joints) by a coating of APPROVED corrosion-resistant material." ... That does not say paint.

In this requirement, I do not see where it mentions that the protection has to be factory provided. Just that protection is necessary - approval is by the AHJ.


Add a lug, scrape the paint - exposing the metal surface, nut and bolt, and if the location is such that protection from deterioration is necessary, add an APPROVED material to protect the exposed enclosure.

Remember - JMHO

Don:

I would make that connection by drilling and taping 1/2-20 providing a lug and 2- 1/4 20 hex nuts to actually lock the connection tight to the threads and enclosure.

On the project we use a GE Mini Load Center with a 480/120/208 transformer with a 12 circuit panel all in one enclosure. That is exactly the way GE provides a ground attachment. That is less one hex nut. They only use one.

Resqcapt:

I would say no since the tapped hole is installed by the manufacture and supposedly the panel has been tested by UL. Plus the fact that I don't recall ever seeing one rusted at the taps.

Paul,
So the only metal to metal connection is the threads? There is no way that 1/4-20 threads have enough metal to metal contact in a field tapped hole to provide an adequate electrical connection. What is the gauge of the metal? The commonly used 10-32 screw only has ~2 threads engaged in field tapped holes in many types of electrical enclosures. The 1/4-20 would have less. If you don't clean the paint off of the enclosure this is the only current path. I don't see it as suitable.
Don

This thread has been interesting with all the commentary on field mods for attaching a conductor to the enclosure...BUT, I am still back at the beginning wondering how comes an EGC larger than the panel will accomodate??? What is the panel mfg/model and the circuit specifics?? Just curious.

Resqcapt:

I notice that you continue to tell me I am wrong but you still do not accurately quote the code. Whats up with that?