Sub-Panel Replacement and Inspection Questions

[89MustangGX]

I just replaced the previously installed (1997) sub-panel in my shop located in Washington. The original panel was permitted and inspected when installed by the previous owner. When I went to replace the panel with a larger panel (physical, not amperage), I noted that the neutral and ground bars were bonded together - which I thought was incorrect. So, on the new panel - I un-bonded them. Because the old panel was permitted, I decided to have the new panel inspected - and the inspector just left. At first, he said it was all good - and then I asked him a question about the bonding of neutral and ground and he looked again and said I needed to change it (shouldn't have opened my mouth!?). He was great about it and let me fix it on the spot, and passes the inspection, but I am not sure it's correct - or at least don't understand it.

Here is what has me thrown:
He told me that because my panel was installed prior to the requirement to pull an equipment ground from the main panel, and it is connected to a ground rod outside (presumably, I have not found it), that I need to have the neutral and ground bonded. Also, I had landed the ground on a ground bar, which he also said needed to be moved to be on the same neutral bar as where the neutral is landed. I can sort of understand the bonding, though I'm not sure it's right - but I really don't understand needing to have the ground and neutral physically on the same bar vs. being bonded through the case.

Can we discuss/clarify both of these points?

 

[mike93lx]

Looks like you have a 3 wire feed, correct? That should be upgraded to a 4 wire feed

 

[89MustangGX]

Looks like you have a 3 wire feed, correct? That should be upgraded to a 4 wire feed

Yes- correct. This is in a separate building, not easy to just "upgrade" it. Just want to make sure it's actually correct and understand why (if) the changes were needed.

 

[billconner]

When I installed a sub panel in a new detached garage, I bonded neutral and ground busses and I stalled a ground rod, and was confident that was correct at that time (2015 but a very old NEC), checking with engineers and inspector who all agreed.

 

[mike93lx]

Read the stickies on why a 3 wire feed is not used anymore. I'd find a way to add a ground wire

 

[89MustangGX]

Read the stickies on why a 3 wire feed is not used anymore. I'd find a way to add a ground wire

Thanks for the replies. I see now where I missed the neutral-ground bonding on 3-wire vs 4-wire before in the diagrams. Having the bond is correct in my case. Regarding the additional ground from the main panel, I appreciate how it would be better, but it's just not practical to go through all the earth, pavement, and concrete between the two panels to install it.

That leaves me with the question of - does the ground need to land on the same bar as the neutral or could I land it on one of the ground bars and have it bond through the case? Or, could it even land on the other neutral bar and be bonded through the strap connecting them?

 

[mike93lx]

I'd have to defer to a sparky. Since this is new, permitted work, I would expect it to have to meet current code. The old panel may have qualified for a 3 wire feeder, but that panel is gone.

 

[BillK]

I think the first thing I would want to do is find out where the ground wire goes ??? Is there any chance it goes back to the main panel ? I wouldnt think so since its not in the pipe with the rest of the wires but you never know. It might also go to a ufer ground. I would want to know.

My detached garage is 4 wire feed with the ground and neutral not bonded. That was code when it was built. If your ground happens to somehow go back to the main panel you might have the same situation.

 

[Bert_]

It looks like three wire so the bond needs to stay. It's important. If you have a three wire feed do not remove the bond.

The reason to go four wire is to keep current off of other metal piping/data/phone wiring. It's really not a big shock hazard like some on here claim. If it was a serious hazard then the utility's wouldn't do it.

 

[89MustangGX]

It looks like three wire so the bond needs to stay. It's important. If you have a three wire feed do not remove the bond.

The reason to go four wire is to keep current off of other metal piping/data/phone wiring. It's really not a big shock hazard like some on here claim. If it was a serious hazard then the utility's wouldn't do it.

Makes sense and I see that now. My next question is - does it matter where I land the ground wire? Does it need to be landed on the same bar as the neutral (as inspector said), or could it be on the opposite neutral bar or even on a ground bar where I had it originally?

 

[wyliesdiesels]

Yes- correct. This is in a separate building, not easy to just "upgrade" it. Just want to make sure it's actually correct and understand why (if) the changes were needed.

Technically since you removed the other panel and installed a new one, code requires the feeder to be upgraded to current code which is 4-wire and isolated neutral.

When I installed a sub panel in a new detached garage, I bonded neutral and ground busses and I stalled a ground rod, and was confident that was correct at that time (2015 but a very old NEC), checking with engineers and inspector who all agreed.

If you did that in 2015, then the engineers and inspectors were all wrong unless for some reason your area was on a code before 2008 which is hard to believe. any subpanel wired after 2008 code cycle is required to be 4-wire with isolated neutral.

It looks like three wire so the bond needs to stay. It's important. If you have a three wire feed do not remove the bond.

The reason to go four wire is to keep current off of other metal piping/data/phone wiring. It's really not a big shock hazard like some on here claim. If it was a serious hazard then the utility's wouldn't do it.

apples to oranges comparison. and it still is a shock hazard. apparently you havent seen the effects of a lose neutral and neutral return current flowing on ground rods and water lines.

Makes sense and I see that now. My next question is - does it matter where I land the ground wire? Does it need to be landed on the same bar as the neutral (as inspector said), or could it be on the opposite neutral bar or even on a ground bar where I had it originally?

It really doesnt matter since the neutral bar is bonded. technically the ground bars and enclosure are at the same potential as the neutral bar due to the green bonding screw.

 

[Norcal]

For a 3 wire supply it’s correct but there those who would say and they are probably correct that the non conforming install has been altered and that it needs to be brought up to current code.

 

[89MustangGX]

Thanks for the replies. I did see code statements in my research about replacing with like items, I believe this is what the inspector meant when he talked about grandfathering in the installation. Maybe it's a state or local thing? I suppose I'm fortunate in that regard. I had no idea this was "non-standard" when I got into it.

 

[Terry D]

If you did that in 2015, then the engineers and inspectors were all wrong unless for some reason your area was on a code before 2008 which is hard to believe. any subpanel wired after 2008 code cycle is required to be 4-wire with isolated neutral.

I cant answer for the OP's area, when I took my master test in 2002, St Louis was still on the 1996 NEC. They remained on that code cycle until they adopted the 2008. I guess it could be possible, although Missouri's code adoptions is governed be each municipality.

 

[Bert_]

Technically since you removed the other panel and installed a new one, code requires the feeder to be upgraded to current code which is 4-wire and isolated neutral.

If you did that in 2015, then the engineers and inspectors were all wrong unless for some reason your area was on a code before 2008 which is hard to believe. any subpanel wired after 2008 code cycle is required to be 4-wire with isolated neutral.

apples to oranges comparison. and it still is a shock hazard. apparently you havent seen the effects of a lose neutral and neutral return current flowing on ground rods and water lines.

It really doesnt matter since the neutral bar is bonded. technically the ground bars and enclosure are at the same potential as the neutral bar due to the green bonding screw.

I've changed many a panel without changing a 3 wire feed that was legal when installed If I replace a feeder then it gets 4 wire. Nobody around here has an issue with that.

I've seen bad neutrals. Most of the time the complaint is bright / dim lights.

 

[nadogail]

I received a packet of guidance from my utility when my service was upgraded and both the main and subpanels were replaced.

My Cabinetmaker had a buddy who specialized in Service Upgrades. He was Fast, Good and lower priced than anyone else.

Inspection went smoothly.