Service Upgrade: Converting Existing Main Panel to Sub Panel

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beerbelly25

Member
Location
OHIO USA
Occupation
Electrician
This subject has been covered fairly well in previous posts, but I'm looking for absolute clarity with regard to neutral and ground separation at the existing (old main panel) during conversion to a sub panel. I had to relocate my main service due to an addition that created clearance problems with the overhead service entrance conductors. I placed a new 200A meter/panel combo in another location on the side of the house and fed aluminum 2-2-2-4 to the existing (old main panel) with a 90A breaker in the new 200A panel. The existing (old main panel) is a Crouse-Hinds 150A and I ordered and installed a separate ground bar made by Siemens/Eaton who apparently now owns the C-H brand. I separated all of the neutral and grounds and ran a temporary #6 stranded copper jumper between the grounds and neutrals to use until the new service goes live. The neutral bus bar is insulated with plastic offsets at the base and a cardboard insulator that extends up to the side of the box to prevent the neutrals from touching the bare metal enclosure and making ground contact. I can't determine if this old panel has a neutral bonding screw. The inspector has passed all of my work on the new 200A panel and is now requiring me to disconnect the neutral wire on the old main panel and the temporary jumper to check for continuity between the ground and neutral bus bars. There are 2 existing grounds on the old main panel that were formerly attached to the neutral bus bar. I relocated those to the newly installed ground bar per the inspectors requirements, but from reading these forums, I feel that these grounds should be removed from the new ground bar in the sub panel (one is a #6 solid copper water line ground and the other is a from a ground rod via #4 stranded aluminum) when the new service goes live because the new 200A main panel has 2 of its own ground rods and is feeding the ground (#4) to the converted sub panel via the 2-2-2-(#4) wire.

Questions:
  • Should the 2 ground wires (from water line and old existing ground rod) be removed from the ground bar on the old main panel after it’s fully converted to a sub panel? There seems to be disagreement on the forums here. The inspector is wanting me to leave these ground wires attached on the newly installed ground bar in the converted sub panel even though a ground is fed from the new panel via the 2-2-2-4 feeder. Should I tell the inspector that this is incorrect?
  • The inspector wants me to shut off the main breaker on the panel we are converting to the sub panel and remove the neutral wire from what is currently the service entrance cable from the neutral lug and remove my temporary jumper going from neutral to the ground and take of a video of me checking for continuity between the neutral and ground bars. This is in order for me to make sure that the neutral is completely isolated on the old panel before conversion to a sub panel.
  • I don’t see a bonding screw on the neutral bar in my old C-H panel. Has anyone worked on the older C-H panels? Is there a bonding screw and if so, where would it be located? When I check for continuity between ground and neutral the existence of a bonding screw should become apparent, but I'd like to know the location of this screw if it needs removed. I’m including photos of the old 150A main panel that is being converted to a sub panel below for your reference.
Thanks for your help in advance!

https://postimg.cc/gallery/7wKhHct
 
The grounding electrode conductors should be connected at the new service panel. Did you look for a label on the old panel that might show the bond screw location?
 
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The old CH panels have a bonding “finger”, not a screw through the bar. The finger goes into a hole on the neutral bar just like the neutrals, with a screw attaching it to the panel can.
 
Technically, the old electrodes are present and must be connected to all the other electrodes to be made part of the grounding electrode system - you cant choose to either remove their GEC or leave them connected to the ground bus of the sub as an auxiliary electrode. That said, I imagine most inspectors would be fine with abandoning old rods if new ones were provided.
 
The panel looks like an old MURRAY/ Crouse Hinds to me. If I remember correctly ( and I may not) the original neutral bond screw is the screw immediately to the left of the main neutral lug. If this screw is removed, the "tab and hole" from the lug is more of a slot. Most likely done to allow a bit of play in the neutral bar for manufacturing tolerances.

Howard
 
You will have to disconnect the neutral at the main panel. As long as nothing touches the ground, the neutral bar should not have continuity to the grounds. Even though the panel's power is off, I would turn off each breaker and then test.

Btw, the panel, assuming the breakers are correct, is an old Bryant panel. Cutler Hammer bought Bryant. They are now CH BR series panels to distinguish them from the standard CH breakers
 
Thanks for your responses! I will leave the old ground connections on my new ground bar for bonding purposes. I'll test continuity between the ground and neutral busses after disconnecting my new jumper and the bare neutral feed from the existing service entrance wires. I'll also turn off all the breakers for the test per Dennis above. This is a C-H box and it's rated for the Bryant BR breakers per the panel label (link below).

According to the panel label (link below):
TO BOND NEUTRAL TO ENCLOSURE, INSTALL SCREW PROVIDED THROUGH TANG ADJACENT MAIN NEUTRAL LUG INTO BACK WALL.

I think I've located the bonding screw located adjacent the neutral lug here: https://postimg.cc/H87hqXrM

Here's a photo of the C-H panel label: https://postimg.cc/hf2dk6q9

Thanks again!
 
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Dennis Alwon said:
You will have to disconnect the neutral at the main panel. As long as nothing touches the ground, the neutral bar should not have continuity to the grounds. Even though the panel's power is off, I would turn off each breaker and then test.

Btw, the panel, assuming the breakers are correct, is an old Bryant panel. Cutler Hammer bought Bryant. They are now CH BR series panels to distinguish them from the standard CH breakers
Click to expand...
See post #5. It's probably a Crouse-Hinds as the OP said. C-H for Crouse-Hinds, not Cutler Hammer. (And, Eaton isn't using the Cutler Hammer brand since about 2012.)
 
Anyone have a chance to check my image above for the Neutral bonding screw? I think I located the bonding screw next to the neutral lug per my comments above.
 
The identified screw in my photo is not green, so wasn't sure if anyone had experience with these panels from the 70's. I didn't know if they used green colored bonding screws back then or if that's a newer thing.
 
The old panel has a 150 Amp main but you are now feeding it with a 90 Amp feed. Did you move some of the original load from the old panel to the new main? If not have you done a load calc to verify that a 90 Amp feed is OK? It looks like there is a subpanel to the left of the old main, did you switch its feed from the old main to the new main? It looks like it's feed by the GE 60 Amp 2 pole breaker.
 
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