Bonding of Subpanels

Originally Posted By: sramos
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Can anyone give me a situation where bonding of a subpanel is appropriate?


I recently inspected a 20 unit apartment complex that had 16 Zinsco Subpanels that were all bonded.


--
Steven Ramos
EnviroVue Home Inspection
866-541-2883

Originally Posted By: Bob Badger
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Well that would not be correct.


For dwelling units the only place I know where a panel that does not contain the service disconnect can be bonded is in a separate building or structure under some strict guidelines.


--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: rpalac
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Zinsco…well that’s your first problem!


Originally Posted By: sramos
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Thanks Guys.


The panels themselves appear to be performing quite well. Not one wire had scorched or melted insulation. The bus bars were not discolored. A few double taps because the panels are older and do not contain enough slots for modern conveniences but that's it - other than the bonding issue.

Other opinions before I wrap up my report?


--
Steven Ramos
EnviroVue Home Inspection
866-541-2883

Originally Posted By: jpeck
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Ramos wrote:
Thanks Guys.

The panels themselves appear to be performing quite well.


Bold statement about ANY panel, much less a Zinsco .

Quote:
Not one wire had scorched or melted insulation. The bus bars were not discolored.


It's what you will likely NOT SEE (until you remove a breaker) that will bother you later when you find out about it.


--
Jerry Peck
South Florida

Originally Posted By: kmcmahon
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Bob Badger wrote:
Well that would not be correct.

For dwelling units the only place I know where a panel that does not contain the service disconnect can be bonded is in a separate building or structure under some strict guidelines.


I think I remember a rather large discussion on this subject about a month or so ago, and where I learned the above statement to be correct.


--
Wisconsin Home Inspection, ABC Home Inspection LLC

Search the directory for a Wisconsin Home Inspector

Originally Posted By: Brian A. Goodman
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I’m reluctant to raise this thread again after 10 days, but here’s that “subpanels aren’t bonded” thing again. Yes they are, they just aren’t bonded on the neutral bar. They should have a seperate equipment ground bar, with its own conductor, which is where the enclosure is bonded (4 wires needed total, but there are certain exceptions for seperate buildings).


In Electrical Inspection of Existing Dwellings Douglas Hansen wrote, "All metal enclosures containing live electrical wiring, including subpanels, must be grounded so they remain at zero voltage potential to ground, and so they have an equipment grounding connection to clear possible faults. The only difference with the subpanel is that the neutral may not be used to accomplish the grounding."

I don't mean to make a horse's rear end out of myself on this, I'm just concerned about misinforming readers.


Originally Posted By: sramos
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In this case, the ground wire was joined with the neutral wire using a clamp. Thoughts?



Steven Ramos


EnviroVue Home Inspection


866-541-2883

Originally Posted By: Brian A. Goodman
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Steven,


The ground wire definitely should not be with the neutral on a subpanel. Subpanels really aren’t that complicated if you stick to looking for how it should be done, and just recognize that anything otherwise is wrong.


Here are the basics you're looking for:
There should be 4 wires instead of 3 (2 hots, 1 neutral, 1 ground). The usual rules apply regarding wire size vs. ratings / load / etc.
There should be 2 terminal bars (ground bars) instead of 1. One bar gets only the neutrals (typically white) and is never bonded. The other gets all of the equipment grounds (typically bare or green) and must be bonded. The two bars cannot be connected to each other in any way, so if there is a factory installed jumper bar between them it must be removed for use as a subpanel.
If it's in the house that's about it, except for the usual panel inspecting details (branch wiring, etc.).

If it's in a seperate building:

it must have its own grounding electrode (typically a ground rod, metal water pipe, rebar, etc.).

it does not require any of the above (4 wires, 2 bars, etc.) only if there is no continuous conductive path between the buildings. In that case it can be wired just like a main panel. Watch out for metal fences, sidewalks with rebar, metal water pipes, telephone or TV cables, etc. When in doubt recommend the full-blown subpanel configuration, it's safer.

If I'm erring or leaving anything out, somebody speak up.

I'd strongly recommend the book I mentioned above to anyone in our business (Electrical Inspection of Existing Dwellings). It was written by the same guys who make Code Check. I like it because it's more conversational and comprehensible than a code book and written specifically from an inspection angle. Just bear in mind that it's not a code book if you need exact or obscure details on specific items.


Originally Posted By: jpope
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I came across one of these yesterday where the feeder panel was bonded to the neutral busbar AND grounds were connected at the same busbar.


![](upload://6Fx4cEq2gFvUd4DBqGYjnZ9Zou1.jpeg)



Funny thing is, this one already had its separate grounding bus installed



Needless to say, this one had to be corrected.


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: cbuell
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I found this sub-panel the other day----brand new construction. The neutrals and grounds were separated but the bar connecting the neutral bar and the ground bar was left in place.



It is easier to change direction than it is to forget where one has been.

Originally Posted By: cbuell
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http://www.nachi.org/bbsystem/usrimages/more/kappa-greimann%20reduced%20(63)2.jpg ]


Originally Posted By: Brian A. Goodman
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In just 2+ years of inspecting I’ve seen almost every possible variation of “how to make a subpanel mistake”. I’d estimate that half of the subpanels I see have some basic error or other, most wired by electricians (or what passes for one here).


Job security! ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)


Originally Posted By: roconnor
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jpeck wrote:
"Thanks Guys ... The panels themselves appear to be performing quite well."

Bold statement about ANY panel, much less a Zinsc

I would agree!

Are ya sure they are "sub-panels" without the "service disconnect"?


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: sramos
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In my case, there was definitely no disconnects and there was more than six breakers installed.


Thanks for the confirmation. I wrote it up as such. I was challenged by the realtor because the apartment manager produced inspection documents from their electrician who billed them over $30k in fees for this apartment complex and made no mention of this problem. Funny thing is they did install two new subpanels during that project, which did not have the ground and neutral wires bonded????

I mentioned this to the realtor and referred him back to the "experts". They obviously know their trade better than I. By the way, I did not change my recommendation.


--
Steven Ramos
EnviroVue Home Inspection
866-541-2883

Originally Posted By: jpope
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I found these feeder panels in a town home complex of about 80 units. They’re properly wired with two separate busbars.


The service disconnects have been upgraded to Square D components, but these remain in the units.

![](upload://56ktkhhm7fQcQm3D5yutE5eS0aY.jpeg)

![](upload://l9MT1948xj5rjus7EyR4xFWwr7i.jpeg)

They look "fine." But I've recently learned that this particular panel had only three breakers that actually functioned. Apparently, they could not be manually turned off as they were frozen internally. So says my local Sparky after following up my recommendation for further evaluation.


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: sramos
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What is the technical mechanism for a “freezing” breaker. Specifically, what happens to the breaker components internally to cause the defect? How would we uncover a condition like this, or would we?



Steven Ramos


EnviroVue Home Inspection


866-541-2883

Originally Posted By: jpope
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I’m not sure what it would be called. I can only assume that they were “frozen” from corrosion, oxidation or possibly over heating.


I would not have known about the condition because I don't open and close breakers as a part of my inspection.

I recommended that this panel be disassembled and inspected simply because of its brand name. A Sparky that I trust did the inspection and told me about the condition.

After hearing of these results, I am leaning more toward Jerry P's position to recommend replacement as a standard (I'm not quite there yet Jerry ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif) ).


--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

Originally Posted By: Mike Parks
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Could I bond (not ground) my “subpanel” to the interior waterlines?


Mike P.