Sub Panel Ground Requirements

House with sub panel 40 feet from main in same basement. Subpanel has neutrals isolated. Grounds are separate and ground bar is bonded to panel.

There are 9 breakers in the sub panel. No main shutoff in the sub…only the 100 amp feeder breaker in the main. Since they are in the same building, I think this is OK? Can someone confirm?

Is a separate ground required from the sub panel to the main?

Not only is not required, its not allowed.

It also doesn’t need a “main breaker”

If it was part of a detached structure, then it would need its own grounding electrode and grounding electrode conductor.

Edit: Disregard. I thought he was asking if the sub panel needed a separate ground as in a GEC to an electrode.

Thanks…do you have a link to a reference on this? I’m seeing conflicting information.

Maybe I need to be more clear…the feed from the main is only 3 wire - 2 hots and neutral. No ground from main to sub.

What kind of conduit is being used?

Dan what is the raceway or conduit between the two panels? Metal?


Sorry Juan beat me to it.


No conduit between the two. Large jacketed cable.

If there’s no metal raceway between the two then the 3 wire feed is wrong. You need an EGC.


Do you have photos?

I will get tomorrow…just dropped off a radon CRM today and took a very quick look at the panel…will take camera back tomorrow. have a good night:) BTW…almost done with HIP template…ready to switch soon!

Good deal Dan. Good night. Good luck with the onsite reporting. Let me know if you have any questions.


Thanks Bert…

So the ground bus is not connected to anything. Is the neutral at least bonded to the enclosure?

Why would the neutral be bonded to the enclosure?


Oh shoot. I read the question wrong. It would help if people used the correct names for things.

Yes you need an equipment grounding conductor from the main to the sub panel.

My fault for not being concise…I’ll get better with experience. Thank you for the constructive and informative responses…all of you.

The only reason I always try to use the correct terminology is because I once made an embarrassing mistake. Ill never make that mistake again. I don’t even like calling equipment grounding conductors as such because its a misnomer.

It was my fault btw. Your question was pretty clear. I just read it too quickly.

All circuits that originate from the sub panel are “ungrounded” circuits, based on the description you’ve given.

If you have a three-wire feed (H+H+N) with no EGC, the fact that the circuit grounds are bonded to panel means nothing. There needs to be a connection back to the service equipment.

If you have a NM cable assembly feeding the sub panel, it needs to be rewired. The EGC must be an integrated part of the assembly. You can’t just run a separate EGC.