Mike Dolt Enterprises
Mike Dolt Enterprises
User: beerbelly25, Location: OHIO USA
Asked on: Thursday, April 10, 2025 at 2:08 pm EDT
Answered on: Thursday, April 10, 2025 at 2:29 pm EDT
Question: 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
Okay, let's break down your situation and address your questions about converting your old main panel to a subpanel
Understanding the Core Concepts
Neutral and Ground Separation
This is the key. A subpanel's neutral and ground MUST be isolated. This prevents neutral current from flowing on the grounding path, which is dangerous. The only place neutral and ground should be bonded together is at the main service panel.
Grounding Electrode System (GES)
This is the system of grounding rods, water pipe bond, etc., that connects to the main service panel to provide a path to earth.
Equipment Grounding Conductor (EGC)
This is the ground wire (your #4 in the 2-2-2-4) that runs with the feeder conductors to the subpanel. Its purpose is to provide a low-impedance path back to the main panel in case of a fault.
Answering Your Specific Questions1. Grounding Electrode Conductors (Water Line and Old Ground Rod)
YES, you should disconnect the ground wires (from the water line and old existing ground rod) from the ground bar in the old main panel after it's fully converted to a subpanel. This is critical for proper subpanel operation. Those ground wires form part of the Grounding Electrode System (GES), which is ONLY connected at the main service panel. Having them connected in the subpanel creates multiple ground paths, which can lead to circulating ground currents and compromise safety. Tell the inspector, politely but firmly, that keeping the grounding electrode conductors (water pipe ground and old ground rod) connected to the ground bar in the subpanel is incorrect and violates code. Cite NEC 250.32(B) which specifically states that at a separate building or structure, the grounding electrode system shall not be connected to the grounded conductor (neutral). You can also refer to other sections that emphasize the single point of grounding at the service.2. Inspector's Continuity Test
The inspector's test for continuity between the neutral and ground bars, after disconnecting the neutral and temporary jumper, is exactly what needs to be done. This confirms that the neutral bar is fully isolated from the enclosure and the ground bar. This is the correct procedure. You want to ensure no connection.3. Neutral Bonding Screw on Older Crouse-Hinds Panel
It is highly likely there was originally a bonding screw or strap. Older panels often used a screw or a removable metal strap to bond the neutral bar to the metal enclosure. If you examine the neutral bus bar and the metal enclosure very closely, look for the following: A screw terminal on the neutral bar that looks like it would contact the metal enclosure. A hole or indentation in the metal enclosure near the neutral bar where a screw might have been. A small metal strap that might have connected the neutral bar to the enclosure. If you find evidence of a bonding screw or strap, and it's still present, REMOVE IT before you energize the new service. If you can't find any trace of a bonding screw, then you can reasonably conclude that the panel never had one or it was removed prior to you working on it. If the inspector finds evidence of a bonding screw or strap, ask him what he wants you to do with it.
Summary of What to Do1. Complete the Continuity Test
As requested by the inspector. Disconnect the main feeder neutral conductor and the temporary ground-neutral jumper. Test for continuity between the neutral bar and the panel enclosure/ground bar. There should be no continuity (infinite resistance).2.
Remove Grounding Electrode Conductors
After the inspector is satisfied, disconnect the ground wires connected to the water line and old ground rod from the ground bar in the old main panel. These need to be connected only at the new main service panel.3.
Ensure Neutral Isolation
Double-check that the neutral bar in the old panel is completely isolated from the metal enclosure. Ensure the plastic insulators are in place and in good condition.4.
Inform the Inspector
Explain to the inspector why you are removing the grounding electrode conductors and cite the relevant sections of the NEC (primarily 250.32(B)). Be respectful but firm. The inspector's job is to ensure safety, and you're demonstrating you understand the code requirements for that.
Important Considerations NEC 250.32(B)
Read this section of the National Electrical Code (NEC) carefully. It is the controlling section for grounding at separate buildings or structures (which is what your subpanel effectively is).
Local Amendments
Be aware that your local jurisdiction might have amendments to the NEC. Check with your local building department.
Communication
Clear communication with your inspector is essential. Explain your understanding and be prepared to back it up with code references.*
Safety First: Always work safely! De-energize circuits before working on them. Wear appropriate PPE (personal protective equipment).I hope this comprehensive explanation helps! Good luck with your project. Flag for review