equipment grounding

[mpd]

Re: equipment grounding

I will ask it again, does anybody know any cases where TA 250.122 did not work because of fault currents? iwire if the NEC had a definition like what you are saying, who would certify that EGC system

 

[iwire]

Re: equipment grounding

Originally posted by mpd:
iwire if the NEC had a definition like what you are saying, who would certify that EGC system

The same person that has to verify that a single ground rod has 25 ohms or less resistance to ground.

The same person that has to verify that the load calculations are correct.

IMO it is the installers responsibility to show compliance with the ground rod or load calculations.

But in order to verify something we need to know what it is we have to prove.

 

[don_resqcapt19]

Re: equipment grounding

Bob,
First off "too fast for conditions" is a very common ticket here in Illinois.

As an EGC can be bare to concern one self with overheated EGC insulation seem fruitless.

The temperature limit of a bare EGC is the same as that of the insulated circuit conductors so that the hot EGC does not damage the grounded ungrounded conductors.
While 250.122 does not specifically say that 250.4 applies to a conductor installed as an EGC, it also doesn't say that it doesn't apply to it. I think that 250.4(A)(5) clearly requires that the EGC be "upsized" in cases where the available fault current would damage the EGC if it was called on to clear a fault.

(5) Effective Ground-Fault Current Path Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.

If the EGC is melted by the fault current, or even it it gets hot enough to damage the insultation on the other conductors there is a violation of 250.4(A)(5).
Don

 

[iwire]

Re: equipment grounding

Originally posted by don_resqcapt19:
Bob,
First off "too fast for conditions" is a very common ticket here in Illinois.

I don't doubt it and it is probably here as well.

I would not hesitate to fight it and expect to win as long as my speed did not result in loss of control.

 

[George Stolz]

Re: equipment grounding

Originally posted by iwire:
I would not hesitate to fight it and expect to win as long as my speed did not result in loss of control.

He's in the jailhouse now
He's in the jailhouse now,
I told him once or twice,
To stop slinging barbs, and pickin' fights,
He's in the jailhouse now...