Do you need an EGC in every parallel conduit?

Yes. NEC 250.122(F)(1) requires a full size equipment grounding conductor in each raceway of a parallel run, each sized from Table 250.122 based on the circuit overcurrent device.

Can the parallel EGCs be smaller because there are several?

No. Each EGC must be full size per Table 250.122. The rule assumes a fault might return through only one raceway, so every conduit carries a complete ground path.

Do Parallel Conduit Runs Need a Ground Wire in Each Conduit?

Straight from the app this week: if I am running 3 separate conduits as parallel sets, do I need a ground in each? Yes. NEC 250.122(F)(1) settles it, and the sizing rule surprises people.

The rule

Where conductors are installed in parallel in multiple raceways as permitted by 310.10(G), an equipment grounding conductor of the wire type must be installed in each raceway, and here is the part that matters: each one is sized from Table 250.122 based on the rating of the overcurrent device protecting the circuit, not divided among the conduits. Three parallel conduits on an 800 amp feeder means three EGCs, each sized for 800 amps from the table, which is 1/0 copper in every pipe.

Why full size in every raceway

A ground fault inside one conduit returns on the path available in that conduit. If the EGC there were undersized on the theory that its siblings would help, the fault current would find a conductor too small to carry it long enough for the breaker to open. The code assumes each raceway may have to clear a full fault on its own, so each carries a complete, full size path.

Metal conduit changes the picture

If the parallel run is in rigid metal conduit, IMC, or EMT, the raceway itself is a permitted equipment grounding conductor per 250.118, and the NEC does not force a wire EGC at all. The 250.122(F) rule bites when you choose to install wire EGCs, or when the raceway is PVC, which is common on underground parallel services and feeders. Every PVC conduit in the set gets its own full size EGC, no exceptions.

Other parallel set reminders

Keep the sets electrically balanced per 310.10(G): same length, same conductor material, same size, same insulation, same termination method, and all phases plus neutral of each set in the same raceway when in metal conduit to avoid inductive heating per 300.20. Minimum 1/0 conductors for standard parallel sets. And where conductors are increased in size for voltage drop, 250.122(B) requires the EGC to be increased proportionately as well.

Parallel feeder math has a lot of moving parts. Ask BONBON handles the table lookups and cites 250.122 chapter and verse so your inspection goes smoothly.