Odd Proposal Statement

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bphgravity

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One of my proposals ( for section 250.58 ) that was rejected had the following panel statement:

The Code is not structured to protect against abnormal conditions such as open neutrals that may develop.


Does this sit well with anyone? What is the point of the Code if not to protect against abnormal conditions?
 
Re: Odd Proposal Statement

bphgravity said:
What is the point of the Code if not to protect against abnormal conditions?
It is to protect against abnormal installations. The code authors cannot create a list of every single thing that might fail within an installation, and require that we install a protective feature for each case. We are required to protect against overcurrent and ground faults and arc faults, and we are required to select components that can handle the currents to which they will be subjected in normal operation. But that's about it.
 
Here is the proposal to give you context for the CMP statement:

Where an ac system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used and the requirement of (1) is met.

(1) An audible or visible alarm shall be installed at each service to indicate the grounded conductor brought to the service has opened.

Exception No. 1: In industrial installations, with written safety procedures, where conditions of maintenance and supervision ensure that only qualified persons service the equipment.

Exception No. 2: Where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision.

Substantiation: Upon the opening of the grounded (neutral) conductor at one service, potentially dangerous current will flow between the common electrode to both services. Any person who comes in contact with exposed metal parts at the service equipment or grounding electrode system could be exposed to lethal current.

The full statement says,

The submitter has not provided any technical substantiation to require monitoring the grounding electrode and grounding electrode conductor integrity by audible and visual alarms. The CODE is not structured...

I don't understand. This has nothing to do with monitoring the GEC or GE. The whole point is to prevent the GEC and exposed metal parts from becoming the normal flow of current. I guess the CMP doesn't consider the possibilities of a hazard to be enough substantiation yet the code is loaded with "what-if" requirements...
 
The fault current goes back to the source. I thought the GEC/GE is for transients, zero potential and overvoltages. If the grounded conductor is compromised then there is the potential for electrical shock if a fault is unable to clear and damage from overvoltages in mutliwire branch circuits. I have seen overheating of panels where the GEC was cut off by thieves, but that was it. Maybe the loss of a zero potential would cause a problem or hazardous condition, but I'm still learning. Please enlighten me.
 
Wavector, welcome to the forum. :)
wavector said:
The fault current goes back to the source.
It wants to, yes, by any path.

I thought the GEC/GE is for transients, zero potential and overvoltages.
That's pretty much right in line with 250.4(A)(1), yes.

If the grounded conductor is compromised then there is the potential for electrical shock if a fault is unable to clear...
If you're saying this can happen and it's bad, I agree.

If you're saying the grounding electrode system is a backup plan for an open neutral, that's not correct. It sometimes does happen that way, especially with interconnected water-pipe electrodes between neighboring services.

I have seen overheating of panels where the GEC was cut off by thieves, but that was it.
Can you elaborate on this? What was overheated?

Maybe the loss of a zero potential would cause a problem or hazardous condition...
The grounding electrode system's ability to bring the incoming neutral to earth potential is debatable. There's several "earths" to consider in that train of thought, too. At any rate, the zeroing (or lack thereof) wouldn't mean much in the way of creating heat, IMO.

I'd say it sounded like the neutral's resistance was going up, and the GEC was acting as a substitute neutral. When the GEC was removed, the deteriorated neutral connection began to overheat. Does that sound right?
 
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