Maker Pro
Maker Pro

Detecting Damaged Romex Cable Insulation

H

Home Builder

Jan 1, 1970
0
Background Scenario:

Part 1) New house with 12-2 romex wiring installed by an electrician who
often justified sloppy work with faulty assumptions. Regarding skimpy
use of staples: "Them wires ain't going nowhere near the drywall screws
but if the inspector says 'sumpin' we'll just tack up another staple
here and there to keep 'em happy". I restapled most cable runs but
probably missed a few areas --- given several thousand feet of romex
used in the house.

Part 2) Thermal/Acoustical Insulation Company comes along yesterday and
sprays foam insulation which pushes some of the poorly stapled romex
runs outside the stud bays, possibly allowing the romex insulation to
be damaged when the excess extruded foam was "trimmed" back to the face
of each stud bay by the foam installer. I asked the foam installer to
let me know if he cut into any wires by mistake and he agreed to keep me
posted, but using a continuity tester I later discovered a low voltage
burglar alarm circuit that had been severed, pushed back into the wall
and covered with extra foam. An accident? Perhaps, but it raises
doubts. Severed wires on 24 gauge circuits are easy for me to detect,
but nicked insulation on 12-2 romex is another story.

Part 3) The foam insulation material (Icynene) began to shrink a
half-day after installation, totally contrary to the manufacturer's and
installer's sales claims, causing me to doubt the honesty and candor
and/or knowledge of the insulation company. If they'll misrepresent the
merits of their basic product, they probably won't be too forthcoming
about collateral damage if/when they can cover it up and hide it from
detection... figuring it won't be THEIR problem if someone gets
electrocuted or the house burns down several years down the road.

I can't think of any reliable way of determining if any of the romex was
damaged without ripping out the foam and visually examining each of the
wires and this will be difficult because the foam clings tenaciously to
wiring insulation. I'm tempted to do this anyway because of the
shrinkage problem but it would be nice to find a way of testing the
insulation on each romex circuit without having to scrap away the foam.

Any ideas?
 
S

SQLit

Jan 1, 1970
0
Home Builder said:
Background Scenario:

Part 1) New house with 12-2 romex wiring installed by an electrician who
often justified sloppy work with faulty assumptions. Regarding skimpy
use of staples: "Them wires ain't going nowhere near the drywall screws
but if the inspector says 'sumpin' we'll just tack up another staple
here and there to keep 'em happy". I restapled most cable runs but
probably missed a few areas --- given several thousand feet of romex
used in the house.

Part 2) Thermal/Acoustical Insulation Company comes along yesterday and
sprays foam insulation which pushes some of the poorly stapled romex
runs outside the stud bays, possibly allowing the romex insulation to
be damaged when the excess extruded foam was "trimmed" back to the face
of each stud bay by the foam installer. I asked the foam installer to
let me know if he cut into any wires by mistake and he agreed to keep me
posted, but using a continuity tester I later discovered a low voltage
burglar alarm circuit that had been severed, pushed back into the wall
and covered with extra foam. An accident? Perhaps, but it raises
doubts. Severed wires on 24 gauge circuits are easy for me to detect,
but nicked insulation on 12-2 romex is another story.

Part 3) The foam insulation material (Icynene) began to shrink a
half-day after installation, totally contrary to the manufacturer's and
installer's sales claims, causing me to doubt the honesty and candor
and/or knowledge of the insulation company. If they'll misrepresent the
merits of their basic product, they probably won't be too forthcoming
about collateral damage if/when they can cover it up and hide it from
detection... figuring it won't be THEIR problem if someone gets
electrocuted or the house burns down several years down the road.

I can't think of any reliable way of determining if any of the romex was
damaged without ripping out the foam and visually examining each of the
wires and this will be difficult because the foam clings tenaciously to
wiring insulation. I'm tempted to do this anyway because of the
shrinkage problem but it would be nice to find a way of testing the
insulation on each romex circuit without having to scrap away the foam.

Any ideas?

You can test the insulation with an meggar. A unit that put out 500 to a
1000 volts will work. Any scraped wire will be found quickly. Can not be
powered up and can not be connected to anything. Recepts and switches ok,
lamps no.

I have a Speary that is ancient, AVO is another brand.
 
B

Ben Miller

Jan 1, 1970
0
SQLit said:
You can test the insulation with an meggar. A unit that put out 500 to a
1000 volts will work. Any scraped wire will be found quickly.

Think "Romex". A megger won't tell him anything. What are you going to meg
it to? Ground? The insulation could be stripped from an area of the hot
wire, but there would be no path for the megger current to flow through.

Visual inspection is the only way to do it reliably.

Ben Miller
 
Top