Ungrounded AFCI?

al hildenbrand · Jul 7, 2005

Re: Ungrounded AFCI?

Hey Folks,

This thread has been an interesting read. Seems to me George is on to something. . .

250.130(C), when applied to an older installation, to me, requires that we think of a specific "general" installation or two.

Permit me to suggest two different single family dwellings, for our consideration.

A detached 1955 single family dwelling on a private well water system with an existing 120/240 V 60 A fused service center.
A detached 1955 single family dwelling on a metal municipal water system with an existing 120/240 V 60 A fused service center.

Both fuse centers are the classic Main and Range 60 A fuse block pulls, and 4 15 to 30 A plug fuses. The branch circuit neutrals land on a neutral bus that is riveted to the enclosure. The grounded service conductor connects to this same neutral bus, as well.

Every one sees these, if they do any amount of residential work in existing dwellings. There are a lot of them still in service, and likely to be so for decades to come.

The most common ground, in my experience, is a #8 copper running from the neutral bus to the closest metal cold water pipe. The water meter may, or may not, be jumpered. The cold water pipe is part of the GES all the way through the dwelling to the clamp holding the #8 copper GEC (grandfathered legal pre-1993 NEC).

Today, when I do the work that George lays out in his last diagram I connect the EGC for "New #1, #2 & #3" to the first 5 feet of water pipe (as per today's NEC).

When the dwelling water system is upgraded, who's to tell me that the plastic pipe (above the ceiling, hidden) separating the water pipe into two pieces is, in fact there?

The water service tests grounded, especially on a municipal metal system, but also on a well.

And the service center neutral tests grounded through the service grounded conductor to the transformer ground. Yet, in the example of a private well water system, the only thing connecting the two metal halves of a plastic separated water pipe GES is the earth itself.

Edit to get the UBB code right...

[ July 07, 2005, 12:53 AM: Message edited by: al hildenbrand ]

hurk27 · Jul 7, 2005

Re: Ungrounded AFCI?

Al are we going back to making POCO supply 4 wire drop since the GES is not a dependable system?

al hildenbrand · Jul 7, 2005

Re: Ungrounded AFCI?

Wayne,

That's kinda another story, I think.

1999 NEC 210-7(d)(3)(b) & (c) look real good to me, unless there is a compelling expectation, at the time I extend the circuit, that a grounded appliance will be used, something like a cable converter box or a desktop computer, etc.

[ July 07, 2005, 01:34 AM: Message edited by: al hildenbrand ]

George Stolz · Jul 7, 2005

Re: Ungrounded AFCI?

Originally posted by al hildenbrand:
1999 NEC 210-7(d)(3)(b) & (c) look real good to me, unless there is a compelling expectation, at the time I extend the circuit, that a grounded appliance will be used, something like a cable converter box or a desktop computer, etc.

How ya been, Al?

I don't have a '99. Could someone post the text?

al hildenbrand · Jul 7, 2005

Re: Ungrounded AFCI?

Hey George,

Life in meat space has been good and consuming. I've had barely enough time to lurk online on occasion till recently.

1999 NEC
210-7. Receptacles and Cord Connectors

(d) Replacements. Replacement of receptacles shall comply with (1), (2), and (3) as applicable.



3. Where a grounding means does not exist in the receptacle enclosure, the installation shall comply with (a), (b), or (c). [list:2f5d3ab8c0]

b. A nongrounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interrupter-type of receptacle(s). These receptacles shall be marked ?No Equipment Ground.? An equipment grounding conductor shall not be connected from the ground-fault circuit interrupter-type receptacle to any outlet supplied from the ground-fault circuit interrupter receptacle.

c. A nongrounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Grounding-type receptacles supplied through the ground-fault circuit interrupter shall be marked ?GFCI Protected? and ?No Equipment Ground.? An equipment grounding conductor shall not be connected between the grounding-type receptacles.

[/list:u:2f5d3ab8c0]

al hildenbrand · Jul 7, 2005

Re: Ungrounded AFCI?

As I reconsider what I'm trying to say, in the light of day, I think I'm not doing so well. The 1999 NEC 210-7 reference above is still not direct enough, even with the supporting of 1999 NEC 250-130(c), which is arguably not direct support.

Until the language written in the Code was developed through the late '90s till now, I could site specific language that permitted the extension of an ungrounded 120 V branch circuit in a dwelling that allowed me to wire grounding receptacles with no equipment ground connected to the device grounding terminal as long as the device has GFCI protection.

Using nonmetallic boxes and conventional 14/2 NMB with ground, and pushing the ground to the back of the box, unused, leaves it available for some future reset when the walls are openned up.

Meanwhile, the problems in an ungrounded two wire circuit are avoided (that George has been wrestling with) that may be created by the introduction of a EGC, that is effectively bonded to the GEC or GES, etc.

The beauty to me of the GFCI / no equipmetnt ground solution is that personel, seems to me, have a greater level of protection for the GFCI.

LarryFine · Jul 7, 2005

Re: Ungrounded AFCI?

Originally posted by georgestolz:
So, if we're all wrong, who won? , I did, waaaaaaaaay back on page 2:

Originally posted by LarryFine:
A GFCI will allow downstream grounding receptacles to be used ungrounded, as long as they're marked as not providing grounding and as long as the grounding terminals are not interconnected.

Click to expand...

So there!

Seriously (hey, it could happen!), this is as unambiguous as the water-pipe five-foot/bonding/grounding-electrode debate. The last time I used a water-pipe as a ground, it was when I was 8 and made crystal radios.

I've been asked several times about changing non-grounding receptacles with grounding ones, and I usually recommend the same thing: If there is no GEC in the box, I suggest instead home-running a new circuit for the item(s) that require grounding, such as a computer.

al hildenbrand · Jul 8, 2005

Re: Ungrounded AFCI?

Larry,

I've been mulling this one off and on, today. I agree with you and with George.

It seems that all the pre-'90's points are still there in the 2005 NEC, just in different articles and chapters.

George Stolz · Jul 8, 2005

Re: Ungrounded AFCI?

Al, the problem with the conclusion I had come to at that point is, the wording isn't strong enough to mean anything.

Since 250.130(C) is permissive, then all it does it guarantee a right to have a EGC running independently of the circuit conductors, in violation of 406.3(C).

(C) Methods of Grounding. The grounding contacts of receptacles and cord connectors shall be grounded by connection to the equipment grounding conductor of the circuit supplying the receptacle or cord connector.

The branch-circuit wiring method shall include or provide an equipment-grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected.

Those two taken togther seem to be all that applies to extensions of circuits.

In retrospect, I think I was wrong when I posted that one.

Al, did you see the proposal I whipped out, due to this discussion?

LarryFine · Jul 8, 2005

Re: Ungrounded AFCI?

Originally posted by georgestolz:
The branch-circuit wiring method shall include or provide an equipment-grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected.

That would apply to a branch circuit being installed now. To me, an extension to an existing circuit is not "a branch circuit".

jwelectric · Jul 8, 2005

Re: Ungrounded AFCI?

To stay with the original post which was talking about receptacles added to circuit extensions we would need to stay with 250.130 as outlined by fine print note #2 found in 406.3 (C). 406.3 (D) only address the replacement of receptacles and has no bearing on circuit extensions.

240.130 (A) states that a connection shall be made by bonding the equipment grounding conductor to the grounded service conductor and the grounding electrode conductor.

Then we drop down to 250.130 (C) where we find that the equipment grounding conductor for the extension can hit the grounding electrode system at any accessible point.

Should this equipment grounding conductor for an extension hit the water line then this water line would be required to be bonded to the grounded (neutral) conductor.

The use of GFCI receptacles would not be allowed in a branch circuit extension. 406.3 (D) is for replacement ONLY.

iwire · Jul 8, 2005

Re: Ungrounded AFCI?

Mike I am glad you brought this up.

Originally posted by jwelectric:
To stay with the original post which was talking about receptacles added to circuit extensions we would need to stay with 250.130 as outlined by fine print note #2 found in 406.3 (C). 406.3 (D) only address the replacement of receptacles and has no bearing on circuit extensions.

I was feeling like we starting to drift into replacement receptacles when we are taking about new receptacle locations.

George Stolz · Jul 9, 2005

Re: Ungrounded AFCI?

Originally posted by LarryFine:

Originally posted by georgestolz:
The branch-circuit wiring method shall include or provide an equipment-grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected.

Click to expand...

That would apply to a branch circuit being installed now. To me, an extension to an existing circuit is not "a branch circuit".

That's a valid point: my reference doesn't exactly "fall into place" regarding these issues.

al hildenbrand · Jul 9, 2005

Re: Ungrounded AFCI?

JW & Bob,

Using FPN #2 in 406.3(C) to lead one to the need for a branch circuit extension to be installed by 250.130 seems fair.

250.130 includes the 250.130(C)FPN to go back to 406.3(D).

If the 406.3(C)FPN #2 has weight to guide installation, so 250.130(C)FPN has equal weight.

al hildenbrand · Jul 9, 2005

Re: Ungrounded AFCI?

I note that the 2005 NECH reference below calls the receptacle installed in the branch circuit extension a replacement receptacle.

That being the case, seems to me, then 406.3(D) is appropriately included in 250.130(C) FPN.

jwelectric · Jul 9, 2005

Re: Ungrounded AFCI?

Al
Look closely at the heading of these two secions:

250.130 (C) Nongrounding Receptacle Replacement or Branch Circuit Extensions.

406.3 (D) Replacements.

In 250.130 we are told that the equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B).
If we are installing a receptacle the only choice we have here is (A) due to the fact that our system MUST be a Grounded Systems.

250.130 (C) tells us we are permitted to connect to any of the following (1 through 5) if we are using a grounding-type receptacle or installing a branch-circuit extension.
This is used only for the replacement with a grounding-type receptacle or when installing a branch-circuit extension.

406.3 (D) applies to the replacement of existing receptacles only. We cannot use 406.3 (D) for the extension of the circuit.

The fine print note found in 250.130- FPN: See 406.3(D) for the use of a ground-fault circuit-interrupting type of receptacle. Would point out the use of GFCI receptacles used for replacement only.

And the fine print note found in 406.3- FPN No. 2: For extensions of existing branch circuits, see 250.130. Would point out the criteria for the branch circuit extension or the use of a grounding-type receptacle used for replacement.

The Exhibit 250.49 that you posted clearly shows the two receptacles are connected with a two conductor with out equipment ground and it is labeled as an existing cable, look closely. This is to show that either an extension or replacement with a grounding-type receptacle will require the equipment grounding conductor to be connected by one of the means outlined in 250.130 (C) 1 through 5.

al hildenbrand · Jul 9, 2005

Re: Ungrounded AFCI?

Think of the use of "replacement" this way. . .

The ungrounded branch circuit extension would have been wired with an ungrounded device, but this is a new installation of the extension, therefore we have to replace the two wire device with another installation. 406.3(D) applies.

al hildenbrand · Jul 9, 2005

Re: Ungrounded AFCI?

Hi JW,

The Exhibit 250.49 that you posted clearly shows the two receptacles are connected with a two conductor with out equipment ground and it is labeled as an existing cable

No, seems to me it is called out at for an existing installation.

Edit to tweak UBB code - Al

[ July 09, 2005, 12:16 PM: Message edited by: al hildenbrand ]

jwelectric · Jul 9, 2005

Re: Ungrounded AFCI?

Again I state that 406.3 (D) is for replacement ONLY and cannot apply to a circuit extension.

406.3 (D) Replacements. Replacement of receptacles shall comply with 406.3(D)(1), (D)(2), and (D)(3) as applicable.

No where does it state extensions.

250.130 (C) Nongrounding Receptacle Replacement or Branch Circuit Extensions .

250.130 applies to the branch circuit extensions

al hildenbrand · Jul 9, 2005

Re: Ungrounded AFCI?

It is real interesting that the new cable installed for the new extension was shown as a cable without an EGC.

I think this is a very carefully thought out example of how the pre-'90's Code points are still present.

Ungrounded AFCI?

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