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Replacing an Old Style Ceiling
Electrical Junction Box |
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Dear Mr. Electrician:
I want to replace a very old ceiling
light fixture in a very old house.
After removing the ceiling canopy cover
that hides all the wiring, I found that
there is no standard ceiling electrical
outlet box. Instead, there is a black
round disc (about 3 inches in diameter)
which has a 1 inch long screw type rod
sticking out of it. The
wires are around around it.
The light fixture that I want to
install comes with a flat hanger bracket and the
instructions tell me to install this hanger
bracket onto the outlet box. Since there
is no outlet box, I don't know what to do.
What are my options? |
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Answer:
I suspect that the round disc is
actually an old black enameled metal
pancake box. It's
approximately the diameter and thickness of
a hockey puck and made out of metal.
An old gas pipe usually protrudes from the
middle of this pancake box. A setscrew
tightens the box to the gas pipe.
This is how old houses that originally had gas
lighting converted over to electric lighting.
An additional fitting or two was required to
attach a light fixture which was made for this
type of installation. Of course the
gas lighting line was normally disconnected when
electricity was brought into the house for the
first time.
Around the center pipe there are four holes,
each with a setscrew or clamp
which engages the cable, prevents it from being
pulled
out, and provides electrical continuity for the
equipment ground for armored cable. The canopy of the old
style ceiling light fixture acted as the
junction box for the spliced wires.
The wiring is most likely armored cable
(BX), however non-metallic (The Type Before
Romex) or knob and tube is possible as well.
Beware if the gas pipe has a cap on it.
Usually the caps are removed when the gas line
is taken out of service. However, until
you can verify that the gas line is dead you
should not remove the cap. |
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In a situation such as this, the best thing would be to install new wiring.
However this not only could be expensive, but
damaging as well. Walls and ceilings may
need to be broken open to re-route old dried and
brittle cables
and install new wiring. |
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Turn off
the power. You will need to
remove the old pancake junction box. Do it
carefully so as to not damage
the existing wiring.
Often, wiring from that era of
home construction now has dry
and brittle insulation on it.
Any disturbance to the wires
could cause the insulation to
break off.
Make sure
that you identify each conductor
in the box before you take apart
the splices. The
color coding is almost gone on
these wires. The wires are
likely to be soldered and
taped. The insulation on
the wires will break off as
you separate the conductors. Get
a roll of
white
and a roll of
black electrical tape. You may need
rolls of
red
and
blue
electrical
tape also.
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The gas pipe will be a hinderance to installing
a new modern octagonal ceiling electrical box.
Also it is quite likely that there is a piece of
wood supporting the gas pipe or the pipe may be
attached to the side of a ceiling joist.
Sometimes a pipe wrench can be put on the gas
pipe to unscrew it from the elbow.
An internal pipe wrench might be needed.
Other options are cutting it out with a
multifunction oscillating tool or a Sawzall, or
relocate the ceiling box. Relocating may
not be an option due to the existing lengths of
the wires. |
Once all obstacles have been removed and the
existing cables have been identified and taped, a
new electrical box can be installed. An
old work ceiling fan brace and box
can be fitted in
place through the existing hole. A
side mount
type is also available if the joist is right there.
Try to get the deeper boxes.
Use the proper connectors and anti-short bushings
for the cables and bring them into the back of the
box. In this case it may be best to put
connectors on the ends of the cables with the
locknuts removed. Tape the ends of the wires
together. As you push the box into the
ceiling, pull the cables through each connector.
Tighten the locknuts by hitting them with a
screwdriver driven by a hammer after the box is
secured to the bracket. |
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You are on http://www.MrElectrician.tv/questions/question-ReplaceCeilingBox.html
Created May 31, 2013
Updated December 15, 2015
Copyright 2015 John Grabowski All Rights
Reserved
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