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Grounding Question


dtontarski
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I inspected a 1963 built home with the meter next to the service panel in the basement. The meter had a grounding electrode conductor connected to the water supply line. The panel did not appear to be bonded to the meter - other than via the incoming neutral service conductor. There were a bunch of equipment grounding conductors terminated under the lug for the incoming neutral service conductor and I called these out and suggested a ground bar be installed to terminate these to. Questions:

1. As is, is this properly grounded? Does the incoming neutral service conductor suffice as a bond between the panel and the grounding electrode conductor from the meter?

2. If a ground bar is installed, should it be bonded directly to the existing grounding electrode conductor, or is bonding it to the panel adequate?

Thanks in advance for your review & advice.

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Dave Tontarski

The Finger Lakes Region of NYS

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Originally posted by dtontarski

I inspected a 1963 built home with the meter next to the service panel in the basement. The meter had a grounding electrode conductor connected to the water supply line. The panel did not appear to be bonded to the meter - other than via the incoming neutral service conductor. There were a bunch of equipment grounding conductors terminated under the lug for the incoming neutral service conductor and I called these out and suggested a ground bar be installed to terminate these to. Questions:

1. As is, is this properly grounded? Does the incoming neutral service conductor suffice as a bond between the panel and the grounding electrode conductor from the meter?

I don't see any reason to further bond the meter can to the panel enclosure.

At one time, the water service pipe was an adequate grounding electrode. Nowadays we like to see a bit more. Still, there's no particular imperitive to upgrade the grounding electrode unless the water service has been changed to plastic.

2. If a ground bar is installed, should it be bonded directly to the existing grounding electrode conductor, or is bonding it to the panel adequate?

I think it would be best to connect it to the neutral terminal bar in the service panel.

- Jim Katen, Oregon

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In this situation, shouldn't the main then be treated as a sub-panel. With isolated neutral and ground bars? If using bx or emt the material itself acts as a grounding agent, where would one connect the ground conductor when using Romex, if not at isolated bars?

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Dave, I'm not sure I follow you exactly, but in the photo I can't see a neutral wire from the meter to the neutral bar in the service equipment panel...is that right? Are you asking if the service equipment panel can be fed with only two wires and a bond via the metal conduit?

Funky-looking breaker arrangement, even for a split bus.

Brian G.

Out On Bond [:-mean]

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Originally posted by Brian G.

Dave, I'm not sure I follow you exactly, but in the photo I can't see a neutral wire from the meter to the neutral bar in the service equipment panel...is that right? Are you asking if the service equipment panel can be fed with only two wires and a bond via the metal conduit?

Funky-looking breaker arrangement, even for a split bus.

Brian G.

Out On Bond [:-mean]

As Fritz pointed out, the neutral runs across the bottom of the enclosure and up the right side. There is no conduit. That's a short length of SE cable.

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(Are you sure you're not old enought to use that 2 million CP light?)

- Jim Katen, Oregon

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Originally posted by StevenT

In this situation, shouldn't the main then be treated as a sub-panel. With isolated neutral and ground bars?

No. The meter is still a meter and the service panel is still a service panel. None of that changes when you connect the grounding electrode conductor to the meter can instead of the service panel.

Remember that the GEC can connect to the neutral "at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means." (250.24(A)(1))

If using bx or emt the material itself acts as a grounding agent, where would one connect the ground conductor when using Romex, if not at isolated bars?

Connect them to the grounding/neutral bars in the picture. The equipment grounding wires and neutrals can be connected here -- it's the service panel.

- Jim Katen, Oregon

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So if it is considered a "main" panel, shouldn't it have an earthen ground? If the earthen ground in the meter pan is ok, doesn't the panel have t o be at least bonded and or grounded back to the meter pan/to where the earthen ground is? If not, shouldn't the grounds and neutrals be isolated? and even if they are isolated, where do the grounds terminate?

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Originally posted by Jim Katen

As Fritz pointed out, the neutral runs across the bottom of the enclosure and up the right side. There is no conduit. That's a short length of SE cable.

Ah-so. Thanks Fritz.

Are you sure you're not old enought to use that 2 million CP light?

Eh? What? Talk into my other ear sonny, it's my good one. [;)]

Brian G.

Live By The Jab..... [xx(]

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Originally posted by StevenT

So if it is considered a "main" panel, shouldn't it have an earthen ground?

No. This panel *could* have the earthen ground (Grounding Electrode System, GES) connected to it, but it doesn't *have* to have it. The GES can connect to the electrical system before the service panel. The location of the GES connection doesn't alter any other requirements.

If the earthen ground in the meter pan is ok, doesn't the panel have t o be at least bonded and or grounded back to the meter pan/to where the earthen ground is?

Yes. The neutral achieves this bonding. This is specifically allowed by 240.142(A)(1). It says:

A grounded circuit conductor shall be permitted to ground non-current-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations: . . . On the suppy side or within the enclosure of the ac service-disconnecting means."

Remember, this is only ok on the *supply side*, not on the *load side*.

If not, shouldn't the grounds and neutrals be isolated? and even if they are isolated, where do the grounds terminate?

If the equipment grounds and neutrals were isolated and an equipment ground experienced a fault, how would the fault clear?

This service panel setup is exactly like the vast majority of other service panel setups with the single exception of the GEC terminating in the meter pan. There's nothing wrong with that. In some areas, it's the predominant method.

- Jim Katen, Oregon

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Jim, thanks for the clarification but this seems darn confusing, I understand the words but not the sense. If the meter panel has a main breaker, it is considered the service panel? If so, how would the system be less safe if there was a main breaker in the meter panel?

To try to clarify, if there was a main breaker in the meter panel, does the pictured panel become a sub panel and suddenly become unsafe because the neutrals and grounding conductors are bonded?

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Originally posted by homnspector

Jim, thanks for the clarification but this seems darn confusing, I understand the words but not the sense. If the meter panel has a main breaker, it is considered the service panel? If so, how would the system be less safe if there was a main breaker in the meter panel?

To try to clarify, if there was a main breaker in the meter panel, does the pictured panel become a sub panel and suddenly become unsafe because the neutrals and grounding conductors are bonded?

No offense meant, but your terminology is extremely confusing to me. There are meters, there are main disconnects, there are main breakers, there are panelboards (panels) and there are sub-panelboards (sub-panels), but in 11 years I've never hear anyone refer to the panelboard as a "meter panel." Is that an Arizona thing?

The main panelboard is always where the main disconnect is - whether that is at the meter or in a garage or in a basement or anywhere else. The main disconnect can be in the form of a throw switch, a pull-block, a fuse or a main breaker.

Any panel downstream from the main disconnect is a sub-panel- even if it has its own main breaker - and it must have the grounded conductors (neutrals) and equipment-grounding conductors (grounds) isolated from one another on separate buses without the neutral bus bonded to the panel enclosure. So to answer your question, yes, if there were a main disconnect at the meter, the pictured panel, regardless of the fact that it has its own disconnect, becomes a sub-panel and is therefore more dangerous because the neutrals and grounds are not isolated from one another.

As Jim has pointed out to you,

A grounded circuit conductor shall be permitted to ground non-current-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations: . . . On the supply side or within the enclosure of the ac service-disconnecting means."

, So, the service grounding electrode conductor and the service grounding electrode can be at the meter while the main disconnect and panelboard can be at a different location, such as in a garage, basement, bedroom, etc. It's not a sub-panel until it is downstream from the main disconnect.

It cracks me up when folks from other parts of the country see a photo of a panelboard in a garage or basement separate from the meter, which has it's own main disconnect, and refer to it as being a sub-panel, simply because it's not co-located with the meter.

Around here, 99% of the services have no main disconnect at the meter. It's extremely rare that I see a panelboard co-located with the meter, or nothing but a main disconnect at the meter and a sub-panel in the home. In fact, in 11+ years, I've only had two inspections where there was a main disconnect located at the meter.

Panelboards here are mostly in garages, sometimes in basements and hardly ever at the meters. The service grounding location here is primarily at that main panelboard where the main disconnect is located, but sometimes it's upstream at the meter, which is, as Jim's citation shows you, perfectly okay.

Now, drive 50 miles north or south of Seattle and it's a whole different situation. There are different ways that these are installed in other geographical areas. You must understand the theory of how the system functions or you're liable to make an egregious error.

If you haven't already done so, I'd suggest purchasing Douglas Hansen's book, Electrical Inspection of Existing Dwellings, reading it, and then immediately re-reading it, in its entirety, so that you get a better understanding of how this stuff works.

ONE TEAM - ONE FIGHT!!!

Mike

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No offense taken. I guess I wasn't clear about my question and am not trying to be confrontational. I'll try to re-state it.

"Any panel downstream from the main disconnect is a sub-panel- even if it has its own main breaker - and it must have the grounded conductors (neutrals) and equipment-grounding conductors (grounds) isolated from one another on separate buses without the neutral bus bonded to the panel enclosure. "

Understood

"if there were a main disconnect at the meter, the pictured panel, regardless of the fact that it has its own disconnect, becomes a sub-panel and is therefore more dangerous because the neutrals and grounds are not isolated from one another."

So if I understand this, the bonding of equipment grounds and neutrals is NOT dangerous or hazardous UNLESS there is an upstream disconnect. The existance of the upstream disconnect MAKES it dangerous. (sorry about the caps, I don't know how to do italics)

Is this a correct interpretation?

""meter panel." Is that an Arizona thing?" No, I made that up all on my own. I expect they will be using it in the next edition of the NEC.

[:-idea]

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Originally posted by StevenT

...... shouldn't the main panel be bonded back to the meterpan, where the GEC is?

It is bonded, via the neutral bonded to both. Another wire would be harmless, but redundant.

Brian G.

Redundantly Harmless & Harmlessly Redundant [:-boggled

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Originally posted by homnspector

. . . "if there were a main disconnect at the meter, the pictured panel, regardless of the fact that it has its own disconnect, becomes a sub-panel and is therefore more dangerous because the neutrals and grounds are not isolated from one another."

So if I understand this, the bonding of equipment grounds and neutrals is NOT dangerous or hazardous UNLESS there is an upstream disconnect. The existance of the upstream disconnect MAKES it dangerous. (sorry about the caps, I don't know how to do italics)

Is this a correct interpretation?

The presence or absence of a disconnect has no effect on the relative danger of neutral/grounding connections.

We want to connect these two types of wires as early as possible in the system and still have them be accessible. After that point, we don't want them connected again. This limits the likelihood that return currents will pass over the grounding wires.

- Jim Katen, Oregon

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"We want to connect these two types of wires as early as possible in the system and still have them be accessible."

Thanks Jim, that makes good sense.

Our power company absolutely requires an exterior accessible main disconnect, so there is usually no question about where the service panel is located.

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Great thread...I'd like to thank the guy who started it......oh wait a minute....that was me.

Seriously...that's the great thing about this forum. One can ask a question on a topic that they are fuzzy on and everyone can benefit from the dialogue that it initiates with the more experienced inspectors that make this forum such a great asset. Everyone...please keep the questions coming. I consider this forum my online university.

Dave Tontarski

The Finger Lakes Region of NYS

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