Distribution panel GEC

If a distribution (sub) panel is connected by conduit to the main disconnect panel is that method of bonding sufficient to replace the 4th wire?

That is not for you to determine (even though it may be okay).

Metallic conduit can be used as the EGC (equipment grounding conductor). It must be continuous and bonded to both enclosures (service and load side panels), and the neutral must be isolated at the load side panel.

If the entire conduit was not visible for inspection, it should be deferred for verification.

GEC = grounding electrode conductor

Very true Jeff, but I was wondering for future reference. The whole system was a mess. Another fused main disconnect with 2 distribution panels - one was a Pushmatic and the other an FPE Stab-lock both loosely connected by conduit. Thanks for your reply.

AS jeff stated…the conduit MAY be fine for the " Equipment Grounding Conductor" to the remote distribution panel. While proving this can be difficult for the HI…it is important to note that IF a person is attempting to do this ( which I am sure they do alot in Illinois ) that all the connections and ko’s and so on it correct within the enclosure for it to even be allowed…not so mention like jeff said…that is it conduit on both ends of the application.

Thanks Paul-

The conduit run was only about 18" so it was easy to check, but the locknut were loose and not secure connections. Referal time.


yeppers....also keep an eye out their for those who also do this with a metal nipple and STILL run (4) wires through the nipple. You can't use the nipple for this and then expect to also use the enclosed conductor.....that creates parallel paths and not allowed.

 This is why the majority of installers will use PVC for the connections between distribution panels.....IF they are going to run a 4 wire setup...but keep an eye open for it...as it would be wrong.

Good info Paul - Thanks

Home Inspectors should not defer something for further evaluation unless evidence or a reasonable issue exists. If the correct conduit is present at both ends, no problem is evident and it would be unfair and out of scope to recommend anything else. Some states have limitations also on this type of reporting.

As a comparison, if you defer that then why not recommend the wall studs be verified for proper spacing? Why not recommend the ground rod be checked to see if it is only two feet long? Why not recommend the ground be dug up to verify the footers are there? See where this could lead?

If other issues are requiring an electrician anyway it could be noted that additional testing may be obtained at the clients discretion but not for that sole purpose (partially hidden conduit) only.

I completely agree.

A few variables exist when using conduit as a ECG. The type of connector (if emt), double locknuts (rigid), rules regarding concentric knockouts, whether or not bonding bushings are required, etc. Not things the average HI is qoing to know.

It would be a complete disservice to refer out unnecessarily. It doesn’t look like that’s the case here, though…

No - the referal in this case is completely justified. In regards to the conduit - the locknuts were loose and poor connections were made.