Adding a subpanel to a subpanel

[FFRKing]

I need some input on how to connect this.
I just built a 30x50 detached shop.
200 amp main panel in the house, neutral and ground bars are tied together. 100 amp panel in detached shop fed from house with 2/0, 2/0, 2/0, #1. Large wire was used to compensate for voltage drop over 240 feet. Neutral and ground bar are separated.
The question:
I would like to put a smaller panel in the other end of the shop and feed it from the larger 100 amp panel. This would be for 2 different welder plugs and 220v air compressor that are in this immediate area. It would prevent me from having to run separate wiring for each outlet. I have a 6 space 100A Homeline panel and would like to feed it from the main using a 60A breaker. Since the 220v uses 2 hots and a ground, would I connect the wiring at the 100A panel to the 2 hots from the breaker and the ground bar or 2 hots from the breaker and the neutral bar? I do have 2, 2, 2, 4 wire for this. What do I do with the ground wire at each end? Should I run another ground rod at the 60A panel if it is already grounded back to the 100A panel?
Connecting the shop panel from the house was pretty straight forward and I understand why grounds and neutrals are the way the are at each end, but this extra panel just had me wondering.
Another question:
Can I install the ground rod at the 100A panel inside the building? It is a pole barn and I would only have to drill thru the 5" concrete floor and would prevent me from having to go thru the wall. Just curious as to whether this would be code compliant. Not a problem if it has to be outside.

Thanks

Chris
www.theflagsaver.com

 

[wyliesdiesels]

I need some input on how to connect this.
I just built a 30x50 detached shop.
200 amp main panel in the house, neutral and ground bars are tied together. 100 amp panel in detached shop fed from house with 2/0, 2/0, 2/0, #1. Large wire was used to compensate for voltage drop over 240 feet. Neutral and ground bar are separated.
The question:
I would like to put a smaller panel in the other end of the shop and feed it from the larger 100 amp panel. This would be for 2 different welder plugs and 220v air compressor that are in this immediate area. It would prevent me from having to run separate wiring for each outlet. I have a 6 space 100A Homeline panel and would like to feed it from the main using a 60A breaker. Since the 220v uses 2 hots and a ground, would I connect the wiring at the 100A panel to the 2 hots from the breaker and the ground bar or 2 hots from the breaker and the neutral bar? I do have 2, 2, 2, 4 wire for this. What do I do with the ground wire at each end? Should I run another ground rod at the 60A panel if it is already grounded back to the 100A panel?
Connecting the shop panel from the house was pretty straight forward and I understand why grounds and neutrals are the way the are at each end, but this extra panel just had me wondering.
Another question:
Can I install the ground rod at the 100A panel inside the building? It is a pole barn and I would only have to drill thru the 5" concrete floor and would prevent me from having to go thru the wall. Just curious as to whether this would be code compliant. Not a problem if it has to be outside.

Thanks

Chris
www.theflagsaver.com

im a little confused by your description. Do u want to hookup this third panel to the garage SUBPANEL or the MAIN service panel. U mentioned both panels in your description...

If u meant garage subpanel, then its easy. Use a 4-wire feeder and isolate the neutral bar just as u did with the first subpanel.

No additional ground rods are needed in the same structure.

U connect the EGC/ground from the 240v outlet to the ground bar in the new subpanel. BTW u might have to purchase a ground bar for that panel...

BTW- how many HP is your compressor?

 

[FFRKing]

I guess maybe it wasn't quite clear if you haven't seen it.
Setup is 200A Home panel -> 100A Shop subpanel -> 60A Shop sub-subpanel.
I was going to wire the 60A with the 2-2-2-4 wire and install a separate ground bar.
My question was about wiring the 220v outlets from the 60A panel. I wire the 2 hots to the the breaker and the 3rd wire to the ground bar and NOT the neutral. Correct? I am sure that this is correct, but for some reason was second guessing it.

Thank you for the reply. What about putting the ground rod inside the building? Is that against code? I just prefer to poke as few holes in the walls as possible.

Chris
www.theflagsaver.com

 

[alfredeneuman]

Thank you for the reply. What about putting the ground rod inside the building? Is that against code? I just prefer to poke as few holes in the walls as possible.

It's perfectly acceptable to install the ground rod in the building.

8' of the rod must be buried, so you would need a 10' rod instead of the 8' in order to compensate for the 5" slab depth. Since you have 8' or more buried it can stick up through the floor for access to the ground clamp.

EDIT: Be sure it's not within the 30" wide by 36" deep dedicated workspace in front of the panel

 

[wyliesdiesels]

I guess maybe it wasn't quite clear if you haven't seen it.
Setup is 200A Home panel -> 100A Shop subpanel -> 60A Shop sub-subpanel.
I was going to wire the 60A with the 2-2-2-4 wire and install a separate ground bar.
My question was about wiring the 220v outlets from the 60A panel. I wire the 2 hots to the the breaker and the 3rd wire to the ground bar and NOT the neutral. Correct? I am sure that this is correct, but for some reason was second guessing it.

Thank you for the reply. What about putting the ground rod inside the building? Is that against code? I just prefer to poke as few holes in the walls as possible.

Chris
www.theflagsaver.com

Yes thats correct on the 240v outlet.

Now do u have rods at the first subpanel?

 

[Slowgsr]

In Canada service is only grounded at point of entry with neutral bonded. Sub services are bonded back to the main service.

Otherwise you create ground loops

 

[alfredeneuman]

In Canada service is only grounded at point of entry with neutral bonded. Sub services are bonded back to the main service.

In the US it's the same. NEUTRAL is grounded only at the service.

The ground rod at the additional building in connected to the GROUNDING system, not the neutral

 

[The Cobbler]

I'm in Canada too, my electrician for my garage build tells me no ground rods for the garage, everything grounds back to the main panel... the only ground is at the panel, in my case bonded to the water line .

 

[wyliesdiesels]

In Canada service is only grounded at point of entry with neutral bonded. Sub services are bonded back to the main service.

Otherwise you create ground loops

I'm in Canada too, my electrician for my garage build tells me no ground rods for the garage, everything grounds back to the main panel... the only ground is at the panel, in my case bonded to the water line .

Theres so many people who are confused on this topic! And u two are some of them!

You're confusing 2 different animals with the same name. An EGC/ground and being bonded to the grounded conductor is different than a grounding electrode. 2 different things that serve different purposes...In the US grounding electrodes are required at detached structures. This DOESNT cause ground loops!

U might want to read this article:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

 

[FFRKing]

Wylie and Alfred,

Thanks for the info. I thought I had it right, but for some reason started second guessing it. The first subpanel (100A) (main garage panel) will have a ground rod. I wanted to make sure that putting it inside the building was OK.
I've been working on this the last couple of weeks. Lots of distractions with 2 daughters coming home from college for the summer. Had a couple of friends out last week to pull the wire in. 240' of 2/0,2/0,2/0,#1. Finished all the wiring in the garage panel except the ground rod and started thinking about a subpanel for the garage. That is now finished also. Last thing is to hook the wiring in at the house.
Going to the lake this weekend with 10 friends from high school. Gonna have to wait till I get back.

Thanks again for the information. Wish I could contribute more around here but most of my experience is with plastic injection molding. Most people don't have one of these in their garage.

Chris
www.theflagsaver.com

 

[wyliesdiesels]

What u need to keep in mind is one set of rods per detached structure. U already have them on your first subpanel in the garage so adding them to the second panel is unnecessary. It wont hurt anything, but maybe your wallet, to add them BUT theyre not required!

BTW 2 rods are required unless u can prove 25ohms or less resistance to earth...