COMMUNITY FORUM

kitty

03:11PM | 11/05/98
Bvelectrical
As part of a remodel, I am planning to replace old (brown plastic) outlets with
new white ones. The outlets in this family
room addition were put in in 1981. The original house was build in 1948. The home
inspector said something cryptic like
"house does not have adequate grounding."
Basically, it looks like the house isn't grounded, most of the electrical outlets
in the house are three prong but don't
have a grounding wire. The family room
outlets seem to have a copper wire, but
I'm not sure if they're really grounded if
the service panel isn't grounded.
Can someone tell me:
1) how we can determine if the main service panel is grounded.
2) is there anything I should be aware of
when changing the outlets (other than turn off the power and copy the exact wiring.)
3) will a GFCI provide protection from electrocution on a 2 wire setup that doesn't
have a copper ground? The fine print on a
GFCI says that it must have a 3 wire with
copper wire to work properly, but some of
the BBSes recommend GFIs as an alternative
to rewiring the whole house.

I'd appreciate any help. Thanks, ~k

DR HOME

10:44AM | 11/09/98
Kitty,
Here are some answers that you will like
and some that you may not.

1. In your service panel there should be a
bare copper wire that runs either to your
cold water line or to a metal rod that is
pounded into the ground outside of your house
or to both.
2. Make certain that the black wires go to the brass screws and the white go to the silver screws (the ground wire would go to the green screw).
3. To work as intended, the GFI will need the ground wire. There are certain shortcuts that may help you but the details are too long to
list on this BBS.

GOOD LUCK!!!!

TomR

08:25PM | 12/19/98
Kitty:

Simply stated, you really need to ground your outlets, all of them. 3-prong receptacles require 3 separate wires; the black (or red) hot wire, the white neutral wire, and, what is usually a bare wire for the ground. This ground wire is probably what you’re missing, and although some later remodels in your home show signs of a remodel, they need to be checked to see what they are hooked up to. You can go to any hardware store and buy a circuit tester. It looks like a 3-prong plug on one end, and has some lights on the other. When plugging into a 3-prong receptacle, it lights up, and the combination of lights will tell you if the proper grounding is present. Of course, it will only plug into a 3-prong outlet.

Most houses built after world war II and before 1960 were wired with plastic-insulated wires wrapped in some type of sheathing. This is similar to modern cabling, except they only had 2 wires (black and white), and houses built since then (more or less after 1962) now carry the extra bare ground wire in the sheathing. This ground wire should tie every outlet box, receptacle, switch, or otherwise, to the main circuit panel , and then on to a grounding rod or water pipe . The safety aspect only works if they (the outlets) are all grounded to each other, and to the main circuit panel.

If these pre-1960’s homes were built using steel conduit or armored cable, it is possible that the municipality would allow you to use this steel sheathing as the ground providing it all leads back to the main circuit panel. Otherwise, a grounding wire needs to be added, and municipalities may not allow just a bare wire running exposed in all the walls. Adding GFCI’s adds a level of protection, but GFCI’s only protect items plugged into them. They can’t easily protect lighting fixtures or light switches, and many items found in the home could cause the GFCI’s to trip just by turning the item on. The ground wire is designed to help protect everything, inside and out. As an esthetic bonus, the grounding of the outlets helps cut down static in TV and stereo reception.

It is also unclear exactly what you have for wires in the wall. 1948 is a fairly transitional year, and, depending on type and condition, replacement may be in order. As a work-around, there are GFCI units that install within the breaker panel itself. Depending on what you have, this may be a viable, albeit expensive option. If you have a fuse panel instead of circuit breakers, this is really not an option unless you replace the main panel. Rewiring an entire house can be pricey, but much of the cost is just for running wire, and that can be a DIY project. If you decide you need to do it, shop around. You may find an electrician that would be willing to work with you on that.

A friend pointed out to me, that unless there are local amendments to the contrary, the NEC allows for grounding of outlets via a separate grounding conductor as long as it is installed so as to be "protected" and is properly connected to the house's grounding electrode system. This can be considerably less expensive than rewiring because you would only have to run a single wire to the outlets for a ground.

In closing, I should point out that both GFCI’s and a properly grounded house are necessary to maximize the protection to both the homeowner and home. GFCI’s are an extension to safety system the grounding wire provides, not a replacement.

There are so many different scenarios that could exist, but lacking the opportunity of a personal visit, the best advice anyone can give to those in these types of situations, is to seek out the skills of a qualified professional who can come to the property, ascertain the circumstance, and make a recommendation. You don’t need to use them for the work, but it will give you an idea on what needs to be done.

Good luck - TomR

Brian Wood

07:44PM | 12/29/98
Dear Kitty: These guys are good,they're also correct. One thing I'm not crazy about though, is grounding a home to a water pipe. Most or all inspectors will insist on Doc's suggestion; pound in a ground rod and be safe. One more thing, if your home, hence wiring, is as old as it sounds, you almost certainly have only #14 wire in your walls. Make sure that you only install GFI breakers rated at 15 amps. Where do you live? I'll volunteer to do the work if it'll get me away from this oppressive heat in South LA.
(Louisiana that is) Happy wiring.

motor-T

02:22PM | 10/10/02
Member Since: 09/27/02
9 lifetime posts
Kitty:
quote:
3) will a GFCI provide protection from electrocution on a 2 wire setup that doesn't
have a copper ground? The fine print on a
GFCI says that it must have a 3 wire with
copper wire to work properly, but some of
the BBSes recommend GFIs as an alternative
to rewiring the whole house.

To answer this question,NO a GFCI does not need an equipment Grounding(Bonding) conductor to work properly. They sense the current leaving the breaker On the hot(Black) and the current returning on the White(neutral) if there is a difference between 4-6 ma thats 0.004- 0.006 amps the gfci will open and disable the circuit. And can be reset by pushing the reset button.
If GFCIs are installed upstream of two wire receptacles they will protect all of the downstream receptalces, without a grounding conductor. In fact once the gfci is installed the protected circuit of two wire receptacles can be replaced with standard up to date 3-wire receptacles; However these receptacles shall be labeled "No Equipment Ground" and " GFCI Protected". These labels are included inside the box with the GFCI.
GFCIs are not intended to extend a circuit either thats an entirely different issue.
As with any electronic device in order to work properly they must be tested frequently. Because line surges and lightning have a tendency to wipe out the electronics without notice they should be re-tested.
They will protect against a line-Ground fault hence the name Ground-fault-circuit-interrupter, but a short across the hot and neutral the GFCI will not see this type of fault.

Mark

bradyp

12:30PM | 10/11/02
Member Since: 09/30/02
2 lifetime posts
If you deside to run an equipment ground for replacement of receptacles. from two prong, to three prong. Can this seperate ground be daisy chained?

tdhorne

07:17AM | 10/13/02
Member Since: 09/01/02
31 lifetime posts
Yes, the Equipment Grounding Conductor (EGC) can be "daisy chained" from receptacle to receptacle. The wire must be concealed in the wall, otherwise protected from physical damage, or number four american wire gauge. Much will depend on the original wiring method used to supply the outlets. If it is the older two wire without ground nonmetallic cable than adding a retrofit EGC is great idea. This is a great technique to combine with GFCI protection because the separate EGC has a higher impedance than one run in the same raceway or cable. Even a relatively high impedance EGC will carry enough current to trip a GFCI and clear any fault prior to human contact and shock. The US NEC only requires a retrofit EGC OR a GFCI to protect three wire grounding receptacles used as replacements for two wire receptacles were the circuit does not contain a ground.

If the existing wiring is old "BX" cable that has the spiral wound metal jacket but no bonding strip than the addition of a GFI breaker or up stream GFCI receptacle is sufficient without adding a retrofit EGC. It is extremely unwise to use the metal jacket of "BX" cable for an EGC without the additional protection of a GFCI because the impedance of such a grounding pathway can be quite high. There are testers and testing techniques that use dummy loads and high quality meters that can be used to test the quality of the Equipment Grounding pathway but, even if the cable shows a low impedance now, in the absence of a bonding strip it can deteriorate to a high impedance condition. The code language on the performance of the EGC is quite clear.

250.4 General Requirements for Grounding and Bonding.
The following general requirements identify what grounding and bonding of electrical systems are required to accomplish. The prescriptive methods contained in Article 250 shall be followed to comply with the performance requirements of this section.
(A) Grounded Systems.
(5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be used as the sole equipment grounding conductor or effective ground-fault current path.

The language quoted below is the section that permits the installation and use of separate retrofitted EGCs to ground replacement three wire receptacles in boxes were no ground is available.

250.130 Equipment Grounding Conductor Connections.
Equipment grounding conductor connections at the source of separately derived systems shall be made in accordance with 250.30(A)(1). Equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B). For replacement of non–grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C).
(C) Non grounding 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
FPN:See 406.3(D) for the use of a ground-fault circuit-interrupting type of receptacle.

The language quoted below is the section that permits GFIs to be substituted for an EGC when replacing two wire receptacles were no EGC is available in the box.

(D) Replacements. Replacement of receptacles shall comply with 406.3(D)(1), (2), and (3) as applicable.
(1) Grounding-Type Receptacles. Where a grounding means exists in the receptacle enclosure or a grounding conductor is installed in accordance with 250.130(C), grounding-type receptacles shall be used and shall be connected to the grounding conductor in accordance with 406.3(C) or 250.130(C).
(2) Ground-Fault Circuit Interrupters. Ground-fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code.
(3) Nongrounding-Type Receptacles. Where grounding means does not exist in the receptacle enclosure, the installation shall comply with (a), (b), or (c).
(a) A nongrounding-type receptacle(s) shall be permitted to be replaced with another nongrounding-type receptacle(s).
(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.
--
Tom

Wolley

01:37PM | 10/14/02
Hi! you said that using only the water supply line for grounding is not enough. Here in Canada, many, if not all, houses built after the 1970's are grounded that way. There are even municipalities (Montreal is one) that prohibit the use of grounding rods as equipment grounding. Could someone please tell me if this method is really that unsafe?
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