SC calcs and current limiting fuses and IEEE 551

xptpcrewx

Power System Engineer
Location
Las Vegas, Nevada, USA
Occupation
Licensed Electrical Engineer, Licensed Electrical Contractor, Certified Master Electrician
Item c allows for use of things that are not in the code, so they would be impossible. For instance, suppose someone came up with a practical room temperature superconductor. would not be allowed because it is not in the current NEC. So it would otherwise be impossible without some kind of special permission.
I disagree. A rule like this to allow for flexibility with innovative/progressive designs and alternatives that meet the same intent as the original rule.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
the code specifically allows for an engineered solution for existing systems. It does not make that allowance for a new system.
Only when you are talking about 110.09, and existing overcurrent protective devices. The NEC provides no guidance for complying with 110.10 and items like relays, terminals, and busbars.
 

xptpcrewx

Power System Engineer
Location
Las Vegas, Nevada, USA
Occupation
Licensed Electrical Engineer, Licensed Electrical Contractor, Certified Master Electrician
Only when you are talking about 110.09, and existing overcurrent protective devices. The NEC provides no guidance for complying with 110.10 and items like relays, terminals, and busbars.
This is a good point especially when applying unlisted equipment. Chances are those acting on behalf of the AHJ will not be qualified or trained in many aspects of design review beyond spot-checking codes, and have no way of really doing a proper evaluation where specialized skills or techniques are involved.
 
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