Pulling in redundant equipment grounding conductor into all metal conduits in all occupancies is CHEAP insurance. British wiring rules require a redundant grounding wire all metal conduits all occupancies and I have opened up enough walls and reconnected EMT enough times ( once ) to know why they have this rule.
All of the gasoline station equipment manufacturers in the U.S. also have such a specification for their equipment.
On 200Y380 to 347Y600 volts and any ungrounded system you definitely do need a green wire in all metal conduits just in case of a weak joint.
If you need to do a funny bend or offset in a larger conduit using a section of liquidtight flexible metal conduit an internal redundant equipment grounding conductor saves on needing a box at each end of the flexible conduit and only an external bonding jumper is needed to get full compliance.
Mike Cole mc5w at earthlink dot net
Michael R. Cole
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