frangible BX connectors

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SceneryDriver

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NJ
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Electrical and Automation Designer
I helped a friend with the electrical gutting and rewiring of his mother-in-law's new (to her) house this weekend. This has been an ongoing weekend project; everything from the service drop to the sump pump outlet in the far corner of the basement is being replaced. The house is ~65 years old, with cloth covered BX to match, and hacked-'n-slashed by the old DIY owner.

What surprised me more than anything though, were the "frangible" BX connectors. They look like the cast metal connectors we all know, except that a sharp rap with a linesman's pliers (or a stern look, really) shattered them to pieces. :jawdrop: It was almost as if they were made of ceramic or dried clay.

I've never come across connectors that bad. Were they just made like this in the past, or has time done something to the metal? At least they were being relied on as the bonding means. Opinions on the longevity of cast connectors and couplers made today? I prefer steel, but sometimes, you use what's available.



SceneryDriver
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I helped a friend with the electrical gutting and rewiring of his mother-in-law's new (to her) house this weekend. This has been an ongoing weekend project; everything from the service drop to the sump pump outlet in the far corner of the basement is being replaced. The house is ~65 years old, with cloth covered BX to match, and hacked-'n-slashed by the old DIY owner.

What surprised me more than anything though, were the "frangible" BX connectors. They look like the cast metal connectors we all know, except that a sharp rap with a linesman's pliers (or a stern look, really) shattered them to pieces. :jawdrop: It was almost as if they were made of ceramic or dried clay.

I've never come across connectors that bad. Were they just made like this in the past, or has time done something to the metal? At least they were being relied on as the bonding means. Opinions on the longevity of cast connectors and couplers made today? I prefer steel, but sometimes, you use what's available.



SceneryDriver

I don't think BX ever had cloth covering.

Is there any way you could post a pic of the connectors?
 

David Goodman

Senior Member
Location
Pahrump, NV, USA
Just a guess here, but the covering sounds like the cloth friction tape I used on my hockey stick back in the sixties. Why it would have been wrapped on a BX connector is beyond me. I've seen old contaminated cast pot metal develop a white powdery corrosion and become brittle.
 

user 100

Senior Member
Location
texas
I don't think BX ever had cloth covering.

Just a guess here, but the covering sounds like the cloth friction tape I used on my hockey stick back in the sixties. Why it would have been wrapped on a BX connector is beyond me. I've seen old contaminated cast pot metal develop a white powdery corrosion and become brittle.

Guys, I think SceneryDriver was referencing the cloth/rubber covered individual conductors inside of the old bx.....

As for the fittings, just sounds like old junk cast fittings.
 
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SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
I don't think BX ever had cloth covering.

Is there any way you could post a pic of the connectors?

Sorry. I wasn't too clear; the individual wires had cloth and rubber insulation, not the outer jacket. The conductors were actually in pretty good shape, all things considered. The insulation was still flexible, and didn't seem crunchy. You could even still tell the white from the black wires. This was definitely BX cable - two copper conductors wrapped in spiral steel armor.

That said, the box connectors looked just like the cast metal ones we use these days - screw goes in at an angle to pin the the jacket into the connector - but shattered with a light smack from a tool. Even the cast metal lock nuts were brittle. No moisture anywhere - the basement and walls are all dry as a bone. I'll try to get a pic if I'm there next weekend. All the old stuff may be gone by then - we did a ton of demo this weekend.



SceneryDriver
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
"BX" has been around for about 100 years the first 40 or so it had only rubber insulated conductors.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Cast pot metal was the cheap option a long time ago. Only had to last long enough to pass inspection. The fact that they couldn't be reused was irrelevant to the high volume builders of the 50s and 60s.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
What surprised me more than anything though, were the "frangible" BX connectors. They look like the cast metal connectors we all know, except that a sharp rap with a linesman's pliers (or a stern look, really) shattered them to pieces.
Interesting description. In all my decades of work in a market of 3 million souls, and in housing stock that has a 95 year history of extensive installation of BX in occupancies, I have never run into connectors as brittle as the ones you have found.

I look forward to your pictures.
 

JFletcher

Senior Member
Location
Williamsburg, VA
Sorry. I wasn't too clear; the individual wires had cloth and rubber insulation, not the outer jacket. The conductors were actually in pretty good shape, all things considered. The insulation was still flexible, and didn't seem crunchy. You could even still tell the white from the black wires. This was definitely BX cable - two copper conductors wrapped in spiral steel armor.

That said, the box connectors looked just like the cast metal ones we use these days - screw goes in at an angle to pin the the jacket into the connector - but shattered with a light smack from a tool. Even the cast metal lock nuts were brittle. No moisture anywhere - the basement and walls are all dry as a bone. I'll try to get a pic if I'm there next weekend. All the old stuff may be gone by then - we did a ton of demo this weekend.

SceneryDriver

So, you find the one BX install that has good insulation on the wires, but the connectors are toast? :lol:

Tin rot, zinc pest... learn something new every day.
 
The pics...

The pics...

As requested. On the positive side of things, they completely shatter when struck.This greatly facilitates their removal.
 

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Other job details.

Other job details.

As for the wire, it was CU BX, but looked like AL. It had rubber insulation, individually wrapped in a threads/fabric, paired, wrapped in a resin paper, and then the outer metal sheath. In general it was in OK shape, but we did find one box with some arcing evidence at the box connector no less, and in a couple places it was crumbly.

Other creative code interpretations by the former owner:

-1/2" CU water pipe used as conduit including one that had a bunch of relief cuts in it so they could cram it into a fitting.
-the 150W incandescent medium base bulb hanging from a lamp socket with string to a water shut off valve handle.
-the florescent fixture supplied via a pair of individual THHN-ish wires half way across the basement.
-the 1/2" drilled hole through the bottom front of the box, through the mounting 2x4, and into an old work plastic box.

The prior homeowner fancied himself an electrician I guess.
 

user 100

Senior Member
Location
texas
As requested. On the positive side of things, they completely shatter when struck.This greatly facilitates their removal.

:thumbsup::cool:

As for the wire, it was CU BX, but looked like AL. It had rubber insulation, individually wrapped in a threads/fabric, paired, wrapped in a resin paper, and then the outer metal sheath. In general it was in OK shape, but we did find one box with some arcing evidence at the box connector no less, and in a couple places it was crumbly.

Other creative code interpretations by the former owner:

-1/2" CU water pipe used as conduit including one that had a bunch of relief cuts in it so they could cram it into a fitting.
-the 150W incandescent medium base bulb hanging from a lamp socket with string to a water shut off valve handle.
-the florescent fixture supplied via a pair of individual THHN-ish wires half way across the basement.
-the 1/2" drilled hole through the bottom front of the box, through the mounting 2x4, and into an old work plastic box.

The prior homeowner fancied himself an electrician I guess.

That would tinned copper in the old bx. The cu water pipe conduit is a first for me, a standard mark of some DIY pro's going the conduit route is white pvc. :D

And I bet there were no tripped breakers due to the arcing box- old bx armor is often not a good fault path even when everything is tight, combine that with aged disintegrating insulation...
 
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al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
As requested.

Zinc%20Pest%20in%20Die%20Cast%20AC%20Connector_zps3uen8fbg.jpg


Thanks. Great image!
 
As for the wire, it was CU BX, but looked like AL. It had rubber insulation, individually wrapped in a threads/fabric, paired, wrapped in a resin paper, and then the outer metal sheath. In general it was in OK shape, but we did find one box with some arcing evidence at the box connector no less, and in a couple places it was crumbly.

Nickel-coated copper from back in the days when the connections would be soldered and then taped. These wires usually cause you no end of trouble in light fixture boxes where the heat from the light fixture degrades the insulation. That's where it will get crumbly.
 

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
I wonder how much can be contributed to the zinc being a sacrificial anode for the cladding, which looks like new in the picture.

I'd wager not much. After spending several days in the basement and crawlspaces, I can say that the house is dry as a bone.


SceneryDriver
 
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