Minimum required EGC larger than phase conductor??

A

Akten

Member
Location
New York
Occupation
Engineer
Hi,

Has anyone run into a situation where the Equipment Grounding Conductor size based on NEC 250.122 gives a size larger than the phase conductor? I have a single phase 1.5HP motor at 208V supply. The motor table 430.248 gives FLC of 11A. I am using #12 awg phase conductors. My circuit breaker setting would be 30A per 430.52. Based on 250.122, the minimum EGC I need is #10.

I don't usually see EGC larger than phase conductor so I would like to know if there is anything I missed or exceptions that allows a lower EGC?
 
250.122 Size of Equipment Grounding Conductors.
(A) General.
Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122. The equipment grounding conductor shall not be required to be larger than the circuit conductors supplying the equipment. If a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.118 and 250.134(1), it shall comply with 250.4(A)(5) or (B)(4).

Equipment grounding conductors shall be permitted to be sectioned within a multiconductor cable, provided the combined circular mil area complies with.Table 250.122.
 
In parallel conductor sets in separate conduits a full sized EGC is required in every conduit. Wouldn't it be possible for the EGC in a conduit to be required to be larger than the CCCs in such a scenario?
 
ggunn said:
In parallel conductor sets in separate conduits a full sized EGC is required in every conduit. Wouldn't it be possible for the EGC in a conduit to be required to be larger than the CCCs in such a scenario?
Click to expand...
Yes because Code Making Panel 5 is on record as saying the circuit conductor for a parallel circuit is the sum of all of the areas of the conductors of a phase that are paralleled. That can result in the EGC in a single raceway being larger than the phase conductors in that raceway.
It appears the 2026 will add language to say that the EGC in a set of parallel raceways will not be required to be larger than the largest ungrounded conductor in that raceway.
 
You must log in or register to reply here.
Top