Single EGC in conduit for multiple circuits

[lmsechrist]

Hello. If the conductors for three 120v circuits share the same conduit, can one EGC be used for all three circuits provided it is sized for the largest circuit? For example, if conductors for one 20 amp and two 15 amp circuits share the same conduit, can one AWG 12 EGC be used for all three? I believe it would be ok because if any of the circuits experience a ground fault, its breaker would open, the EGC is actually oversized for the 15 amp circuits, and one versus three EGCs would reduce conduit fill. Thank you.

 

[480sparky]

Only one is needed, sized to the largest circuit.

 

[kwired]

This is found in 250.122(C):

(C) Multiple Circuits. Where a single equipment grounding conductor is run with multiple circuits in the same raceway, cable, or cable tray, it shall be sized for the largest overcurrent device protecting conductors in the raceway, cable, or cable tray. Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c).