Grounding Bushing on a Subpanel?

[Jon456]

My understanding is that grounding bushings are rarely required downstream of a service panel. I assume that's because of the overcurrent protection offered by the breakers in the service panel. So does that mean grounding bushings are not required for a remote subpanel on a detached building?

Here's what I'm looking at: At the detached building, I'm there's a buried PVC conduit service feed transitioning to IMC just above ground level, entering a service disconnect subpanel which then feeds a meter via IMC (all mounted on the building exterior), which then feeds a lighting and appliance service panel via IMC (mounted inside the building). Just to be clear, the subpanel on the building in question is fed 220VAC via 4 wires (3 conductors + ECG) from a service panel on another building, so it is downstream of a breaker.

The guys who installed this subpanel neglected to add a grounding electrode system at the subpanel. So while I'm in the process of correcting that, I got to wondering if there should be any grounding bushings (there currently are none) on the metallic raceways feeding the service disconnect subpanel and/or the meter base.

 

[tom baker]

My understanding is that grounding bushings are rarely required downstream of a service panel. I assume that's because of the overcurrent protection offered by the breakers in the service panel. So does that mean grounding bushings are not required for a remote subpanel on a detached building?

Typically, no. Service raceway bonding is per 250.92, raceways with condutors over 300 V ph-ph required bonding around concentric or eccentric KOs per 250.97

But I will often use a bonding bushing on a feeder raceway, for example on the outside of a blg to a large box, where the raceway could get hit by a vechicle, esp if it goes into concentric Ko's

 

[benaround]

jon456,

What you have is a detached building, the feeder is in pvc and transitions to

imc at grade level to a disconnect mounted on the building, from the disconnect

it feeds a meter using imc then into the building to a 120/240vac panel. The

feeder contains an EGC.

What you don't have is:

a pvc service conduit feed,
a service disconnect subpanel,
a L&A service panel.

After the service that feeds a building everything else is a feeder.