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Old 03-21-2012, 07:11 AM   #1
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Odd Old Wiring


Hi,

I currently live in a house with (ancient) 2-wire ungrounded outlets. However, the (ancient) breaker box says "3-wire service" on a sticker inside it, and also mentions something about GFCI breakers (some of that sticker was torn off so I couldn't read the whole thing).

So does that mean that the breaker box is grounded, and the outlets aren't? Or that the breaker box is lying to my face and it's actually only two wire? If I find that it's not grounded to the outlets can I install GFCI outlets for a similar amount of safety?

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Old 03-21-2012, 07:19 AM   #2
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Really need pictures of what you are talking about.

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Old 03-21-2012, 07:28 AM   #3
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Really need pictures of what you are talking about.
I'll have to do that when I get home in 7 hours, but pictures really won't show much more than what I've said.. I'm just quoting the labels inside the breaker box unless you want pics of the breakers themselves.
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Old 03-21-2012, 07:34 AM   #4
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If you have ancient two wire ungrounded outlets, but the box says "GFCI" somewhere on it, then somewhere along the way the box was replaced, most likely to switch from fuse to breaker, to accommodate more circuits, or because a breaker had failed and new breakers for the old box were no longer available. How old is the house itself?

All this is to say that no, you probably don't have grounded outlets, but pictures of the inside of your breaker box would help. If the outlets are two prong then they are not grounded. If you have BX cable or similar, then it possible that your circuits are grounded but a closer look inside your box would be necessary to determine that.

Don't go opening your breaker box if you aren't comfortable with how to do it safely.
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Old 03-21-2012, 08:03 AM   #5
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If you have ancient two wire ungrounded outlets, but the box says "GFCI" somewhere on it, then somewhere along the way the box was replaced, most likely to switch from fuse to breaker, to accommodate more circuits, or because a breaker had failed and new breakers for the old box were no longer available. How old is the house itself?

All this is to say that no, you probably don't have grounded outlets, but pictures of the inside of your breaker box would help. If the outlets are two prong then they are not grounded. If you have BX cable or similar, then it possible that your circuits are grounded but a closer look inside your box would be necessary to determine that.

Don't go opening your breaker box if you aren't comfortable with how to do it safely.
Thanks for your input!

The house was built somewhere around 1925-1930 but has been remodeled at least once since then, and has had an addition done at some point in the 60's. The wiring appears to be pre-Romex to one closet outlet that has external wiring; it's cloth covered, rubber insulated wiring but appears to be in decent shape without any cracks. (But I'm not sure if that wiring is used throughout the house, or just to specific receptacles.) The breaker box looks to be from the 60's as well and has 100 amp mains that's broken up into 40A (oven) and various 15 and 20 amp circuits. There is a GFCI outlet in the kitchen that isn't labeled "ungrounded." I know that 2-wire outlets are ungrounded, but I've also read that it was common to wire grounds to outlets and just not use them.

I'll try to get some pictures of the breaker box when I get home, but I'm not sure if I'll be able to take the cover off since it's built into the wall.
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Old 03-21-2012, 08:09 AM   #6
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Odd Old Wiring


I just re-read your original question. I think you can safely assume that the box itself is grounded. You should be able to take the cover off...recessed flush boxes should have a cover panel that comes off with a few screws. If the box is grounded you'll see the grounding wire coming into it.
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Old 03-21-2012, 08:12 AM   #7
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The three wire indication on the panel just means you have 2 hot legs and a neutral. This has nothing to do with whether your receptacle are grounded or capable of being grounded.
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Old 03-21-2012, 08:28 AM   #8
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Circuit grounding (with properly installed ground wires aka equipment grounding conductors) protects equipment and to some extent protects people.

Ground fault circuit interrupters offer even more, nearly absolute, protection to people and do not require circuit grounding.

GFCI receptacles may be installed anywhere they fit easily, although putting them on a circuit with a GFCI breaker back at the panel is redundant overkill. Every few months, use the test buttons on GFCI breakers and receptacles to be sure the GFCI protection is working.

Where a GFCI receptacle is installed on a non-grounded (2 wire) circuit it must be labeled "GFCI protected, no equipment ground" although before some time in the past, perhaps 20 years ago, the label was not mandatory. Downstream receptacles protected by a GFCI's load terminals are also nowadays labeled "GFCI protected, no equipment ground".

Receptacle grounding may be added later by running a bare wire of like size from the outlet box down to the panel with the associated breaker, exactly, somewhat, or vaguely following the path of the circuit conductors or feed cable. BX cable or similar flexible spiral metal conduit does not qualify as circuit grounding unless there is a straight through bare wire or strip inside against the metal spiral.
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Last edited by AllanJ; 03-21-2012 at 08:50 AM.
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Old 03-21-2012, 09:50 AM   #9
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Originally Posted by Jim Port View Post
The three wire indication on the panel just means you have 2 hot legs and a neutral. This has nothing to do with whether your receptacle are grounded or capable of being grounded.
Oh I see now, upon further research I learned that it has something to do with the phases instead of grounding. That probably means that my load center is not grounded given the era of the home and the wiring that I can see. Thanks!

Quote:
Originally Posted by AllanJ View Post
Circuit grounding (with properly installed ground wires aka equipment grounding conductors) protects equipment and to some extent protects people.

Ground fault circuit interrupters offer even more, nearly absolute, protection to people and do not require circuit grounding.[...]
Thanks for clearing all of that up! I'm glad to know that my GFCI breakers/receptacles will protect me when there's an electrical fault, I've been really concerned about the old wiring in this house and will probably end up adding grounds to at least two outlets simply because of the equipment (expensive computers and TV's) that will be used with them but for the mean time I feel better about the situation. For simple grounding purposes can I use clamps on the large steel drainpipes in this home? Is there a way to test the grounding capabilities of the pipe before using it?

Last edited by snofox4; 03-21-2012 at 10:16 AM.
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Old 03-21-2012, 10:24 AM   #10
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Oh I see now, upon further research I learned that it has something to do with the phases instead of grounding. That probably means that my load center is not grounded given the era of the home and the wiring that I can see. Thanks!
Panel grounding and receptacle grounding are two entirely different thing and purposes. Your panel should have been grounded when it was installed. Commonly this is to metallic water lines or grounding rods driven into the earth.

As far as grounding the receptacles there are only a few acceptable places to connect the grounding conductors. Using a drain line is not one of them.

As an alternative I would advise you to run new grounded circuits and leave the old stuff alone. This takes the loads off of the older circuits and is about the same amount of work as grounding the old circuits.
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Old 03-21-2012, 10:28 AM   #11
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You may not attach a wire to the green screw of a newly retrofitted 3 prong receptacle, and lead the wire over to a water pipe to clamp it on. That is not a proper grounding procedure.

But nothing keeps you from daisy chaining a ground wire from one piece of equipment (television, etc.) to another with the far end connected to a drain pipe or radiator. If you were to rig up a 100 watt incandescent light, one terminal to the hot prong of a receptacle and the other terminal to the drain pipe, and with the light on you measured the full 120 or so volts from hot to ground, then would adequately ground the equipment. Note that a GFCI receptacle will trip almost instantly, before the light came on.
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Old 03-21-2012, 10:36 AM   #12
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Originally Posted by AllanJ View Post
You may not attach a wire to the green screw of a newly retrofitted 3 prong receptacle, and lead the wire over to a water pipe to clamp it on. That is not a proper grounding procedure.

But nothing keeps you from daisy chaining a ground wire from one piece of equipment (television, etc.) to another with the far end connected to a drain pipe or radiator. If you were to rig up a 100 watt incandescent light, one terminal to the hot prong of a receptacle and the other terminal to the drain pipe, and with the light on you measured the full 120 or so volts from hot to ground, then would adequately ground the equipment. Note that a GFCI receptacle will trip almost instantly, before the light came on.
Drain pipes and radiators are not listed as code acceptable connections for equipment grounding conductors. The list is very specific. Here is Article 250.130(C)

(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions.
The equipment grounding conductor
of a grounding-type receptacle or a branch-circuit extension
shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system
as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure
where the branch circuit for the receptacle or
branch circuit originates
(4) For grounded systems, the grounded service conductor
within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar

within the service equipment enclosure
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Last edited by Jim Port; 03-21-2012 at 11:21 AM. Reason: added code article
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Old 03-23-2012, 12:57 PM   #13
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Okay, so I haven't taken any pictures but I can tell you this house is wired very strangely.

I changed or inspected 10 outlets and 5 light switches. The main house circuits are as follows: (They are ungrounded circuits unless otherwise specified.)

100A Mains

1 15A| Porch Light / Outside
2 20A| (Grounded) Bathroom light and outlet, (Grounded, GFI) 2 Kitchen counter outlets and kitchen light, 1st bedroom ([external wiring] 2 outlets), 2 living room outlets (one ungrounded GFI), Foyer light
3 20A| 1 kitchen outlet, 1 refrigerator outlet, 2 living room outlets
4 + 6 40A| Stove
5 15A| Unknown (May be Foyer outlet)
6 15A| Unknown
7 15A| Unknown
8 15A| (Grounded) 2nd bedroom

The load center is grounded to neutral and ground on the same bar, all of the grounded circuits have newer 12 ga Romex, but the ungrounded ones have older rubber/twine insulated 10 ga pigtails from the main wiring and the fridge has rubber/fabric insulated 12 ga Romex in good condition.

Should I have an electrician put the kitchen or living room on a different circuit? I know that I never come close to overloading the circuits (maximum used wattage on circuit 2 is 1780w with everything running including a 1kW microwave). Circuit 3 never breaches 800w. And I changed where loads are located so the circuits are well balanced with everything running normally.

Last edited by snofox4; 03-23-2012 at 01:02 PM.
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Old 03-23-2012, 03:10 PM   #14
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Old homes are gifts from your grandparents. You never know what they hold, but they will be full of surprises.
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Old 03-24-2012, 09:16 AM   #15
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Just because you don't see a ground wire in the cable, doesn't mean that that cable isn't grounded.

From what you are describing, I would turn off power to the outlets you want to change, replace them with self-grounding type outlets, turn power on, buy one of these, and determine what the tester says. If it shows correct wiring, you are good to go. If not, then I would call an electrician or install GFIs in the recepts that show no ground.

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