Hi All, I'm wondering if someone can help me with this. All the outlets in my house are two prong plugs fed by armored cable. The cable serves as the ground wire. I've replaced a few of them with grounded (3 prong) outlets and when I've tested the ground it's been fine. I am replacing a few upstairs and the tester reads "no ground". They are both on the same circuit. There are a couple of more outlets upstream (toward the source).
My questions are:
1) Is it possible to ground these outlets? if so, how?
2) How can I test the ground on the upstream outlets without replacing with a three prong outlet? (it seems all testers are three prong)
If the upstaris are armored as well, then check for a poor contact in your ground. Your tester might claim no ground, but you might have a poor one, and you need to search it out and correct it.
Good question, I would check with a multimeter. Check your voltage between the ungrounded conductor(the hot) and the box/yoke(if it's in good contact with the box).
Now remember, only qualified personnel should perform any electrical maintenance.
It could be that the circuits upstairs are fed by a non-armored cable at some point. You could replace the breaker on that circuit with a GFCI breaker. That's what I did in my house because I have non-ground romex. I replaced the 2 prong outlets to 3 prong and put in GFCI breakers Most states approve this method and is code, plus you'll have protection now .
If you are using one of those cheap 3 LED testers to test your ground, you should be aware that it cannot test the quality of the ground and the grounds may not be adequate. I don't know the proper way to test the ground.... hopefully someone else will.
In order to answer your questions competently I'll need some information from you first. Is the metal jacketed cable in your home Type AC armored cable that has a metal bonding strip inside the jacket to assure continuity or is it the older BX cable that has the spiral metal tape jacket with no bonding strip?
You can test the upstream outlets with a solenoid tester such as an Ideal Vol Con or a Square D Wiggy. Do not use a digital multimeter as the readings can be rather deceptive. In order to get a complete picture of the quality of the Equipment Grounding Conductor (EGC) condition you would need to test the EGC under load. An electrician can do that using a dummy load, a testing adapter, and a DMM but it does require experienced judgment to perform the test safely. The other way to test for ground quality is to use an electronic circuit tester such as the the Ideal Sure test. With that instrument you plug it into the receptacle, or into a three to two wire adapter that has been bonded to the yoke of the receptacle, and then push the button. It applies a momentary load and measures the voltage drop on both the not neutral circuit and on the hot EGC circuit. If you can rent or borrow that instrument you can test the EGCs your self. The sure test runs about three hundred dollars new.
Will one of those $10 multi-meter work? I just put the red plug in the hot hole, and white one on the ground hole or neutral hole of the receptable. They all measure 120V. Is this the right way?
Code also requires you to mark each outlet as no equipment grounding provided, or something like that. Was there an official inspection, and how did they require this marking?
There is no code requirement to do anything with the interior bonding strip but most electricians will wrap it around the outside of the armor and clamp it under the connectror. The real function of the strip is to bleed off high frequency transients and the leading edge of a fault since the spiral armor tends to act like a choke. The strip "shorts out" the loops.
I think I do have to mark the outlets, but I never got around to it yet. I did not have an inspection. At somepoint down the road if I sell my house the buyer will get it inspected independently I guess.
I just went asking my code enforcement person at town hall, and it appears unless you are doing something the is 'large' panel replacement, house reconstruction, or adding an addition, there is no permit for how owners doing work. But, all work must be done to the NEC, and he suggested that you get it inspected immediatly by a third party. Guess no surprises when you go to sell later.
Sounded like good advice, but it seem to give me now artistic license to do anything I want, per code ofcouse. ;)
Good discription, it provides for a solid ground, but as for the code, I think like everything it falls under 2002NEC110.3(b). Follow the manufacturer's instructions.
If it has only the spiral tape jacket and no bonding strip it is BX. Type AC has a bonding strip inside the jacket to short out the individual spirals of the metal tape jacket to each other and make them behave more like a continuous steel tube electrically speaking.
Since there is no bonding strip inside the spiral metal tape jacket you have two choices. If you want people protection you install a Ground Fault Circuit Interrupter (GFCI) to protect the circuit. The best place to install that is as a GFCI Breaker in the panel. I suggest that it be installed in the panel that contains the Over Current Protective Device because when a circuit goes dead you will check there as a matter of course. If you use a receptacle type GFCI then when it opens you will have to know were it is installed and remember that the circuit is protected by a GFCI that is in another room. Finding which GFCI has tripped when they are not in a panel is a pain. If you need a low impedance Equipment Grounding Conductor (EGC) for operational reasons other than for human safety then you will have to install one as permitted by article 250.130 of the US NEC.
"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) 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
[Handbook commentary] Because of the requirements of 250.52(A)(1), an interior metal water pipe more than 5 ft from the point of entrance of the water pipe into the building is no longer allowed to serve as a connection to the grounding electrode conductor. " copyright 2002 National Fire Protection Association.
You may well find it is more cost effective to run a new fully grounded circuit to the particular equipment that you need to have grounded for non human safety reasons than it is to run a separate EGC back to the Service Equipment or to the Grounding Electrode System.
That is only partially true. When armored cable was first manufactured it was by the general electric company and the plant in which the work was done was located in the Bronx. Thus the company name for the product was BX. That product was manufactured before the need for a Equipment Grounding Conductor (EGC) to be run with the circuit conductors was well understood. Since GE was first to market with the product it's catalog code became the generally used name for that type of cable. In modern practice the term BX is generally associated with that early product that had no EGC. When the classification of type AC cable was first devised it came at the time when the need for the EGC was just becoming broadly accepted. Thus type AC is generally associated with the bonded jacket cable and bx is generally associated with the older un bonded product.
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