"Greenfield Grounding

[forcebjj]

Getting conflicting info, is a grounding conductor required for greenfield larger than 3/4 ? I always put one for 3/8 and 1/2

 

[kwired]

Getting conflicting info, is a grounding conductor required for greenfield larger than 3/4 ? I always put one for 3/8 and 1/2

There is no simple answer as the answer varies with a few conditions. The requirements are all in 250.118(5) which says:

Listed flexible metal conduit meeting all the following conditions:


a. The conduit is terminated in listed fittings.
b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground- fault current path does not exceed 1.8 m (6 ft).
d. If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed.

Key items you seem to be asking about are that the contained circuits must be 20 amp or less and total length of flex in any one EGC path needs to be 6 feet or less. Many of your installations of 3/8 or 1/2 possibly don't require an EGC be installed.

3/4 and larger often is containing over 20 amp circuits so those do need an EGC installed.

 

[infinity]

Quite often FMC is used to provide flexibility {(d) in kwired post} which would require an EGC regardless of size. Something like a 3/8" fixture whip wouldn't require it.