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)
Thank you in advance for any advice.
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 .
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?
tom @ www.URLBee.com
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. ;)
tom @ www.URLBee.com
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
> 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.
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.
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.
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.
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
(1) Any accessible point on the grounding electrode system as described
(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.
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?
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