To reuse or not to reuse wire...

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K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I hooked up an electric space heater for a business owner that was penny wise and dollar foolish.

The unit was a 440 three phase resistance heater that required to be fed with #6. Owner had piles of old nasty #6 he pulled from somewhere else and wanted me to use it. I told him that I would rather not, but since I was getting paid by the hour I just made the attempt.

The stuff was so old it was brittle and took me and a bull rider to pull in the 27 foot run, one time bull rider boy actually pulled my pipe off the wall. We did get it in, though. I think I had four hours into it and bully boy had not quite two.

So me and Mr. Owner are standing under the heater basking in it's warmth when the explosion occurred. It seems a strand of wire made it's way through the old insulation and made contact with my solidly grounded conduit and blew a hole clean through the EMT. Sparks flew around us as we were not far from the run. Mr. Owner became weightless for a micro-second and may have wet himself. 277 to ground makes a pretty big boom.

This made my case to use new wire. I cut out the EMT along with the wire inside and use it in my radio classes to illustrate what electricity can do if left to it's own devices. After I got the wire and burnt pipe out, I pushed in the new #6 unassisted in about minute or so.

I also use the nifty teaching tool when the powers that be decide they want to use left over wiring and or equipment.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Because the jacket on the older BX was not suitable for use as an EGC.
The older BX jacket, the jacket without the drain wire in intimate contact with it, was, by Code, suitable for an EGC.

When the Code changed to specify that the BX jacket had to be in intimate contact with a drain wire, the older style BX jacket could no longer be an EGC in new installation under the new Code.

Here's my original post with the Code citations from last summer.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Mr. Owner became weightless for a micro-second . . .
Great story! :grin: :grin:

I agree with others in this thread that the salvaged BX (without drain wire) cannot be reused in new situations, regulated by today's NEC, that require the BX to be an EGC.
 

mkgrady

Senior Member
Location
Massachusetts
Yeah, I hadn't thought about the electron drain thing. What happens when a wire runs out of electrons, does it just stop conducting ? :D

In AC it never runs out. The trons go back and forth. But in DC the wire eventually runs out of trons and must be replaced with fresh copper or aluminum but aluminum runs out faster.
 

e57

Senior Member
In AC it never runs out. The trons go back and forth. But in DC the wire eventually runs out of trons and must be replaced with fresh copper or aluminum but aluminum runs out faster.
Are you lacking a smiley, or are you serious?
blink.gif
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I don't know how to do a smiley. Wish I did
Easy. Open the My Profile menu to get into Your Control Panel. Under Settings & Options, select Edit Options, and scroll to the bottom to Miscellaneous Options. In the drop-down menu, select Enhanced Interface - Full WYSIWYG Editing. ;)

Now, when you respond or quote, you'll see a whole palette of new toys to enhance your posting pleasure. Hovering over the various icons will explaing what they do. There are tools for adding pictures and links, and even a box of Smilies. :)
 

Telc

Member
Is this older BX with the cloth covered insuation? Any case I wouldnt use unless it was AC with a ground wire in it.
 

mkgrady

Senior Member
Location
Massachusetts
Easy. Open the My Profile menu to get into Your Control Panel. Under Settings & Options, select Edit Options, and scroll to the bottom to Miscellaneous Options. In the drop-down menu, select Enhanced Interface - Full WYSIWYG Editing. ;)

Now, when you respond or quote, you'll see a whole palette of new toys to enhance your posting pleasure. Hovering over the various icons will explaing what they do. There are tools for adding pictures and links, and even a box of Smilies. :)

Thanks Larry! Always wondered how :)
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I would not be moving old cable and using it for new runs.

Existing runs that can be reused in place might be considered if the spec allows it and the stuff is in good shape.

It might just be easier to scrap out all the old crap and start over.
 
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