NEC Article 430 Part IV confusion 1

[patm72]

On the interpretation of Article 430 part IV from NEC (Motor Branch-Circuit Short-Circuit and Groud-Fault Protection), I am quite confused by the term "Ground-Fault Protection". While I understand the difference with the other member, "Short-Circuit", I am wondering what the use of fuses brings that is different in terms of the Ground-Fault detection when compared to a circuit breaker. Or, more simply stated, what kind of detection hardware/functions must a circuit breaker have to fulfill the requirement?

In fact, I want to validate if a circuit breaker having LSI settings (via electronic trip) can meet the 430.52 requirement, knowing that I am well within the Table 430.52 maximum settings. Am I good witb the LSI? Or should I use a LSIG to qualify?

Thanks.

 

[jraef]

The term "Ground Fault Protection" in this frame of reference is not to be confused with GFCI (Ground Fault Circuit Interrupter) type protection or GFPE (Ground Fault Protection for Equipment) type protection. The use of the term needs to be taken in its entirety: "Motor Branch-Circuit Short-Circuit and Ground-Fault Protection" predates the existence of what we collectively refer to now as "Ground Fault" as a stand-alone term. It just means the short circuit protective device will trip on a fault from phase-to-phase or on phase-to-ground, but will NOT protect the motor from a thermal overload; that must be specified elsewhere. basically, any circuit breaker or even an "Instantaneous Trip" (IT) only breaker, better known as an "MCP" (so long as it is part of a factory assembled combination starter). No need for LSIG (or even LSI for that matter), any standard Thermal Mag breaker meets the basic requirements for this.

The way it is worded confuses a LOT of people, you are not alone, but it's a legacy from the early 1920s I think.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[patm72]

Jraef, thanks for your feedback, much appreciated. Confirming somehow what I was understanding.