Does Art 430.52 or the NEC actually say that ground fault prot for motors is required?

[DG2010]

I am a new specifying engineer and I have customers and people including my boss that say that ground fault protection is not required for motors. I believe that ground fault protection is required for all motors but I'm unsure if the NEC explicitly says it. Looking though art 430 there doesn't seem to be a direct requirement to have ground fault for motors. The nearest thing I can find is the general requirement is 110.10 short-circuit current ratings and other characterizes but even this section only speaks to ground fault in blue text. I'll list some articles below to discuss:

- 110.10 (NEC 2021) generally says to me that equipment shall be protected for types of faults available. Ground faults are available and need to be protected by is my interpretation. However this would imply that all protection devices would require ground fault protection, since all breakers do not require ground fault then this doesn't actually support that ground fault is required for motors.
- 430.51 (NEC 2021) specifies devices intended to protect motor branch-circuit...
- This doesn't say to me that ground fault is required, instead it is specifying devices that would be "intended" for ground fault if there is a "specific" or "particular situation" (blue text) required ground fault. Again I would say that 110.10 is the specific situation that would require ground fault protection for all motors. I just don't see why NEC doesn't appear to say "Ground fault protection is required for all motors Art 430.51".
- 430.52 (NEC 2021) (C) (1) says to me that the protective device shall be for short-circuit and ground-fault.

The follow up question if ground fault prot is required then what should they be sized to? A fuse or CB can be sized for ground fault available for IEEE arc flash & short circuit calculations but where do equipment ground fault protectors (UL 1053) come in where protection is provided in difference in phase current/neutral in mA ?

 

[tom baker]

Please look at the part titles in art 430

 

[augie47]

Is it possible the folks who say motors don't need "ground fault" protection are thinking "GFCI" as opposed to "faults to ground" ?
It is not uncommon for 430.52 to be misinterpreted to imply GFCI.

 

[don_resqcapt19]

The language in Part IV of article 430 is poor. The term ground fault, has many different meanings and the this part does no make it clear what meaning they are talking about. The rule in question is really talking about a line to neutral fault, which is the same as a line to EGC fault. This does not require any special type of protective device. Any of the devices in Table 430.52 can provide the required protection.

 

[tom baker]

“The breaker protects the wire, the overload protects the motor” is a what to understand Art 430 requirements.

 

[DG2010]

The language in Part IV of article 430 is poor. The term ground fault, has many different meanings and the this part does no make it clear what meaning they are talking about. The rule in question is really talking about a line to neutral fault, which is the same as a line to EGC fault. This does not require any special type of protective device. Any of the devices in Table 430.52 can provide the required protection.

Ok I see. Since some manufactures have MCP's that allow for different ground fault settings, and ground faults are generally lower than short circuits, I was thinking that the NEC wanted separate ability to protect against ground faults. I think you are right though, they just establish a maximum value for different types of fuses/CB's trying to evade nuisance tripping, and will trip on short circuits then eventually trip on ground faults. No separate ground fault prot is required then unless short circuit study for a large motor or something would call for it.