Thread: Grounding/bonding in sub-panels

Ok, I've searched and read a few of the prior threads...but they confuse me even more...so let's try again. I'm a relatively new inspector (about 1.5 years) and I have been seeing a lot of these lately...which makes me think I'm not seeing something because it's hard to believe so many people would install these wrong...

First it would help if someone would define "sub-panel" for me...for instance if someone runs out of breaker slots and adds a panel directly next to the main panel that does not contain a single shutoff switch, is that still considered a sub-panel?

I'm seeing a lot of sub-panels lately where the neutrals and grounds are on the same busbar. Attached is one example. In this case, this is in a detached garage and only has 2 20A breakers...there is no single shut-off switch for this panel other than the feed in the main panel. If these are supposed to be on separate busbars...where in the heck is the other busbar...I didn't see another one they could use?

Also, is it a problem that there is no "dead front" on the subpanel?

Thanks to all for your help.

Dave

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The third photo is another example, different house....similar question/issue.

Dave,
Before Jerry explains a Sub Panel is in a Submarine I'll try to get this typed in.
Any panel that is not the "main" or "service" will be downstream from it and will be a sub panel.
Sub's are connected through a breaker on the main panel and can be next to the main or in a different building. The neutrals are supposed to be floating (not bonded to the panel box or have a grounding connection) and the grounds need to be bonded to the panel. You sometimes have to buy the second bus bar for the grounding conductors for these panels. If the neutrals and grounds are connected to the same bar (as in your picture) they are not properly installed.
That said, you should have asked this question 1.6 years ago so you could be a better inspector.

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Your third picture has grounds and neutrals in the same lugs. This is not allowed in any panel whether it is Main - Sub or Other.

There are instances in detached buildings where a 3 wire feed was run and the neutrals and grounds were again re-bonded. This was a code compliant method and is still allowed to be used if existing. There could be no metallic paths between the two buildings.

Jim,
You are absolutely right! I had one of those about two years ago in a 50's home and the Dallas Electrical Inspector told me it was grandfathered. He didn't like it but that was to code at the time. I didn't get the impression it was still allowed.

Dave,

Now is a good time to revise the terms you use - instead of all the other terms you know or have been posted below, think of electrical panels as follows:
- a) service equipment - that is the panel with the service disconnect (main disconnect) in it
- b) all other panels are therefore "other than service equipment" panels - refer to them as remote panels (they are remote from the service equipment), or simply refer to them as "panels"

That means you have "service equipment panels" and you have "panels".

The neutral is only bonded the ground at the service equipment panel.

Jim mentioned a rare exception which used to be allowed, but the key to only applying that exception to when it applied are these:
- separate building, if it is not in a separate building ... forget about the exception
- 3 wire feeder, if the feeder the the separate building is 4 wire (contains a grounding conductor) ... forget about the exception
- metallic path, if there is a metallic path between the buildings (metal water pipe, phone line, intercom, TV antenna lead, ANY metallic path) ... forget about the exception
- consider the exception only if there is a 3 wire feeder and no metallic paths between the buildings
- - in which case the feeders to the separate building basically considered as connecting to "service equipment" and the neutral is bonded to ground in service equipment ... oh, and the exception was removed in 2005 as I recall and is now, as Jim said, only applicable to installations which were installed before the 2005 NEC.

It's not quite that simple .. . but it almost is that simple ...

Gary, I did ask this question 1.6 years ago...and I've been writing these up as improperly bonded/grounded when I see them. I am asking the question AGAIN because I can't believe so many people do it incorrectly. Do you guys also see this done wrong all the time? I'd estimate that I see this on more than 50% of the panels I look at. When I see anything that often, it makes me think I'm missing something.

The note about sometimes having to buy the ground busbar separately is a good one...as sometimes I don't see another logical place they could hook the grounds to within these panels...another reason for my confusion.

Thanks to everyone for your input.

Dave

Originally Posted by Gary Burnett

Dave,
Before Jerry explains a Sub Panel is in a Submarine I'll try to get this typed in.
Any panel that is not the "main" or "service" will be downstream from it and will be a sub panel.
Sub's are connected through a breaker on the main panel and can be next to the main or in a different building. The neutrals are supposed to be floating (not bonded to the panel box or have a grounding connection) and the grounds need to be bonded to the panel. You sometimes have to buy the second bus bar for the grounding conductors for these panels. If the neutrals and grounds are connected to the same bar (as in your picture) they are not properly installed.
That said, you should have asked this question 1.6 years ago so you could be a better inspector.

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Your third picture has grounds and neutrals in the same lugs. This is not allowed in any panel whether it is Main - Sub or Other.

I've been doing this almost 12 years, and it is a rare week when I don't see this. Welcome to the party.

Around here, if the sub doesn't have a State electrical inspection sticker on it, 99% of the time it's done incorrectly.

Why do we see mistakes in remote (sub) panels? Because they are easily installed without permits by homeowners.

Re: the exception in a separate building, I look for a grounding conductor included with the feeder from the main. Simple. If it is there, forget the exception, as per JP's post.
Sometimes there will be only three wires from the main but it is 120 volts only, so still grounded at the main only. One hot, neutral and ground. Watch for that one.

Always check for a bonding screw on the neutral bus. It should be removed. Quite often there will be a recycled service panel with the bonding screw left in.

Originally Posted by John Kogel

Why do we see mistakes in remote (sub) panels? Because they are easily installed without permits by homeowners.

Re: the exception in a separate building, I look for a grounding conductor included with the feeder from the main. Simple. If it is there, forget the exception, as per JP's post.
Sometimes there will be only three wires from the main but it is 120 volts only, so still grounded at the main only. One hot, neutral and ground. Watch for that one.

Always check for a bonding screw on the neutral bus. It should be removed. Quite often there will be a recycled service panel with the bonding screw left in.

Thanks John yes I've caught several of those bonding screws left in too!

Thanks everyone else for your help.

If the feeder is only 3 wires and the panel is 120/240 the bond screw needs to be installed.

Originally Posted by Jim Port

If the feeder is only 3 wires and the panel is 120/240 the bond screw needs to be installed.

Only if the panel is in a separate building.

If not in a separate building ... they got a problem.

Just to confirm...it's rare to see it correct! Here's two different branch panels in a $3 million, 1 year old home I inspected yesterday for its 12 month warrantee expiration: The left panel has the bonding bar between the grounded and grounding bar intact, the panel on the right has the grounding bar isolated (atop plastic) and lacking a bonding screw or flange.

A note about my understanding of detached buildings: A single 120V,15 or 20 amp breaker can have a 3-wire feed, any 240V must be 30amps minimum with a 2 breaker max and a four wire feed, any more breakers than 2 would require a 60amp minimum 4-wire feed. All four wire feeds require separating grounding from grounded and a ‘local’ earth electrode bonded to the panel frame and grounding conductors.

I don't see how you could have an unbroken GEC connecting both the service panel and another panel downstream, at least not in a practical sense.

Originally Posted by Jim Port

I don't see how you could have an unbroken GEC connecting both the service panel and another panel downstream, at least not in a practical sense.

Splices would be made with irreversible crimp connections.

The GEC could be continuous (with the irreversible crimp connections) and have a short pigtail from the GEC to the grounding terminals in the service equipment and panels.

In the practical sense, that would not be hard to do; however, also in the practical sense ... it would be much easier to just bond the interior metal water piping to the service equipment.

Originally Posted by Marc Morin

A note about my understanding of detached buildings: A single 120V,15 or 20 amp breaker can have a 3-wire feed, any 240V must be 30amps minimum with a 2 breaker max and a four wire feed, any more breakers than 2 would require a 60amp minimum 4-wire feed. .

Where are you getting these rules from?

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Originally Posted by Marc Morin

A note about my understanding of detached buildings: A single 120V,15 or 20 amp breaker can have a 3-wire feed, any 240V must be 30amps minimum with a 2 breaker max and a four wire feed, any more breakers than 2 would require a 60amp minimum 4-wire feed. .

Where are you getting these rules from?

California Electrical Code 2010:
225.39 (a) & (b) 230.79 (a) & (b) & (d) 250.32 (b) 250.50

If the CEC agrees with the NEC the 225 and 230 artlcles only require the disconnecting means to be rated at 15 amps minimum or 30 amps. It does not say the feeder or circuit needs to be that large.

Uh? 120V 3-wire 15 or 20amp, 120/240V 4-wire 30amp 2 circuit w/earth electrode, 120/240V 4-wire 60 amp w/earth electrode are not mentioned anywhere in the code regarding separate buildings?

Not concerning the size of the feeder.

It would be ridiculous of the code to specify a 60 amp feeder to a shed simply because it needs more than a single circuit.

Also the 6 throws or less still applies to outbuildings as a disconnect means

Sounds like there might be a case where the code does not say what some think it says. Can you post those CEC articles?.

I'll pile on....

Around here, no one and I mean NO ONE, calls them remote panels and I have better things to do than explain remote vs. sub to a confused client. And like all of you, I see sub panels wired incorrectly.........every single week! This week could be the exception, but I have two inspections today, so it's not over yet.

Originally Posted by Lon Henderson

I'll pile on....

Around here, no one and I mean NO ONE, calls them remote panels and I have better things to do than explain remote vs. sub to a confused client.

I'll add to your pile and raise you one ..

I can only remember 1 or 2 times when a client actually understood what a "subpanel" might be.

Most gave the same fake knowing look, though.

Same when I would say "panel".

However, as soon as I said "electrical panel" they all knew what I was talking about. Some would respond with 'You mean where the fuses/breakers are? ' - yep ... that's the electrical panel.

Don't take those knowing looks as them actually "knowing" - it's all part of the subconscious act of not wanting to appear as if they didn't know.

Another point to consider is that the service panel would exist before any downstream panels and should already have the water line ground.

Originally Posted by Jim Port

Another point to consider is that the service panel would exist before any downstream panels and should already have the water line ground.

All the panels may well have been installed at the same time.

Down here there are lots of homes with an exterior service equipment panel containing only the main service disconnect - the "main" panel is inside (that inside panel may also be the "only" panel.

Or there may be two "main" panels inside.

Or a "main" panel inside with a sub fed panel fed from a breaker in the "main" panel.

Or a "main" panel sub fed off an intermediate panel with the service equipment outside (the panels are inside).