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wrote:
On Sat, 04 Feb 2006 22:44:00 -0600, zxcvbob
wrote:

Member, Takoma Park Volunteer Fire Department wrote:

grodenhiATgmailDOTcom wrote:

After doing more research online it seems there's a chance of there
being a ground even though there's still a 2 prong outlet (I guess this
was sometimes the case in the 50's). I'm going to buy a tester and
determine if this is in fact the case. If this is not the case, I
think I'll trade off and install a GFCI outlet on the first outlet in
the circuit then change the others (in said circuit) with three prong
outlets. Still none would be grounded, but it would still be to code
(or that's the impression I get). Being a first time home buyer, I'm
trying to save where I can and learn as I go. For things like
electrical, before trying to "experiment" I like to get an idea of
what's involved and determine from there.

No one who knows what they are talking about will tell you that what I'm
about to suggest is required by code but I'm going to suggest that you
use isolated ground receptacles for your replacement receptacles that
will be supplied from the Ground Fault Circuit Interrupters. The reason
that I suggest this is that with metal boxes and especially with older
armored cable that does not have a bonding strip a fault on any plugged
in load can energize the other three wire loads that are plugged in or
metallic fixtures supplied by that circuit.

Isolated ground receptacles assure that any fault is isolated to the
defective cord and plug connected load rather than having stray voltage
present on the rest of the ineffectively grounded or ungrounded circuit.
You still label the receptacles as having no equipment ground. The
code already requires that no equipment ground connection be made to
receptacles that are installed from an ungrounded GFCI protected supply
but the connection between the receptacle grounding terminal of a
regular receptacle and it's yoke make that instruction ineffective at
isolating the receptacles from each other.

Isolated ground receptacles are also a lovely shade of orange. HTH :-)

Bob

If it was built in the 50's there is a good chance it has BX, which is
a metal spiral around the wires. Since they didnot have plastic boxes
back then, I assume you have metal boxes, Therefore you have a
ground. TEST THEM ALL TO BE SURE.

You need to run a green pigtail wire from the box to the outlet.
Those older metal boxes did not always have a hole for a ground screw.
Get a ling enough drill bit to drill holes in the rear of the boxes.
In the electrical dept, they sell an alectricians multi-sized tap.
But one to thread the holes, OR get self tapping screws with a hex
head and use a nutdriver. I believe the green ground screws are a
10-32 thread (I may be wrong). Be sure you dont chop up the wires
with the drill chuck.

Here's a tip. Shove then in a piece of small sized hose and bend them
upward. That's my own "invention". I always keep a few pieces of 6"
gas line hoses in my electrical toolbox. just for that purpose, and
they have come in handy a few times when I opened a box and found bad
wires, but needed to keep the wires live to test to find the source.
Just slip them over the wires during the tests. (not premanently -
replace all bad wires). I also used them a few times when working on
a live circuit with lots of wires. Helps keep hands away from the
ones you are not testing at the time, without having to bend that old
insulation so much. Just slip the hose over the wire ends.

There are two types of Armored cable. One is BX that was built in
General Electrics Bronx plant; hence the designation BX; which has no
bonding strip inside the armor. The other is a product of later
manufacture that has a bonding strip in the armor and is more properly
referred to by it's electrical code designation of AC. BX is not
suitable for use an Equipment Grounding (Bonding) Conductor. The
corrosion between the turns of the armor makes the impedance of the
return pathway too high. Before you try to use the armor of the cable
in your walls as an EGC you will need to check for the presence of a
bonding strip. If there is no bonding strip then you will need to
protect the circuit with a Ground Fault Circuit Interrupter. When
unbonded BX cable carries fault currents the result is often a fire due
to the heating of the armor.
--
Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.