ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
UL 508A SPACING
by ale348 - 03/29/24 01:09 AM
Increasing demand factors in residential
by tortuga - 03/28/24 05:57 PM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (ale348), 302 guests, and 14 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 2 of 3 1 2 3
Joined: Dec 2001
Posts: 440
Likes: 3
Member
Anyone ever worked in a building where circuits are not allowed to be turned off? I've worked in many highrise buildings in downtown Houston. Ever been waiste deep in a lay-in or spline ceiling adding a receptacle onto a hot circuit, you back the wire nut off the neutral, and the joint comes apart in your hand? Been there, done that... Ever come behind another contractor who has put about 9 extension rings on a 1900 box (4" square box)? After digging through about 50 joints, you pull out the circuit you need, and it falls apart in your hand. I'm a twister, and a taper. Above are just a few reasons why I tape, and twist. I'm not knocking anyone who doesn't, but it seems like I've had bad experiences coming behind those who don't.
This is not a new subject. It seems like it just comes up from time to time.
HMEL #688


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Oct 2000
Posts: 5,392
S
Member
Notes from the real world there, Watt Doctor. [Linked Image]

Ok , let's experiement....

repeat the following twice.........

Take a piece of #12, hang from rafter,wirenut on another piece of #12, allow for wieght to be introduced at the end of this.

Lab #1--pretwist.

Lab #2---no pretwist.

Add 1 lb at @ time.....

I'll take Lab #1 for a sawbuck......
[Linked Image]

Joined: Dec 2000
Posts: 4,294
Member
Yeah, Doc.
I've done that, but not in Downtown Houston.




[This message has been edited by electure (edited 12-28-2001).]

Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
I'm a 'Twister' too. I can't imagine what would be wrong with taping a device. I've always done it. Found a few photos in our Archives that demonstrate some of the things being talked about here.

This is one of Joe T's that is a Favorite of Mine;
[Linked Image]

This one was taken after a wirenut fell off when touched;
(See what's wrong??)
[Linked Image]


Bill
Joined: Oct 2001
Posts: 597
E
Member
Scott,

I've come to think of this as the religion of wirenuts. [Linked Image]

I believe the better wirenut is one that has a void builtin between the insulating shell and the spring wire coil cone. As a group of conductors are tightened into the nut, the spring wire coil cone deforms, it expands as it cuts into the sides of the conductors, a process that creates more drag as more conductor is "threaded" into the constriction of the coil, to the point that the conductors are twisted. In my opinion, the twisting of the wires by the wirenut itself results in the greatest surface contact between conductors that can withstand the dynamic state of contact that exists as the wires change physical size when heated and cooled by load and ambient conditions. When the conductor ends are placed together, untwisted, and tightened into the wirenut, the spring wire coil cone expands only, with no relaxation.

The spring wire has a memory. When deformed, the coil only partly returns to its original shape. When I remove a conductor from a wirenut, I install a new wirenut.

While not as pronounced as removing a conductor, I maintain that pretwisting and cutting off the excess results in a similar looseness in the spring wire. When the copper strands are twisted, the copper's own memory will result in a slight relaxation in the twist. When the cutter removes the excess, the circular grouping of strands is crushed ovate, significantly oval, and adds a "set" to the relaxed grouping of strands. Now, when the wirenut is applied, the spring wire is stretched wider than the diameter of the conductor bundle by the long dimension of the oval cut end until cutting and compressive forces overcome the "set" and finally start recompressing the twist in the conductors. In my opinion, part of the spring, a few turns, at least, will have been overstretched and be in contact with the conductors only by virtue of the memory of the spring wire, therefore with less force.

The connection I close up in the j-box is one that will be moving for the next hundred years. . .hopefully [Linked Image]. . .and I want the spring that is designed to follow that movement to be in the peak of its compressive force range, therefore, I don't pretwist. The labor of twist and trim I apply to getting the ends together so I have no pullouts.


Al Hildenbrand
Joined: Dec 2001
Posts: 440
Likes: 3
Member
Al,
I'm right with you when it comes to replacing a wirenut that I have removed. I would say that 7 out of 10 times that I remove a yellow wirenut, it goes into the trash. When I remove a red, I use my best judgment as to whether I chunk it. A grey or blue is practically indestructible, and I would very rarely throw one away.
Your case stated above is very sound. I only have one argument against it. The spring inside of a wirenut is conically shaped (did I say that right? [Linked Image] I mean shaped like a cone). I would think that the "overstretching" portion of your argument would be negated by this fact.
IMHO the mechanical strength of the joint shouldn't rely on the wirenut. I want the joint to stay connected without the use of a wirenut, and the wire nut to provide the insulation. If you remember, they used to solder all joints, and then apply insulation. I've never broken an old soldered joint that wasn't twisted.
While I'm on my soapbox, let me throw something else into the mix. Take a knife for example. The reason that some knives are serated is because a serated knife has more cutting surface in same the length as a regular blade. So, a knife with a 4" blade that is serated may have 4.25" of cutting surface. I'm not an engineer, but I just wonder if the same principal applies to twisting wire together. Twisting provides more surface contact? Maybe?
HMEL #688

[This message has been edited by The Watt Doctor (edited 12-30-2001).]


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
OK, You guys know my feelings on this from another thread started last August (that seems to have been removed?). I use Ideal Wirenuts, and a wrenching tool. No pretwisting, but the final outcome is superior, the twists are there and a tighter "weave" is achieved.

[Linked Image from kellyelectric.electrical-contractor.net]

The top pair of wires was pretwisted, the bottom pair was not. See any difference?

I'll shut up now.


[This message has been edited by sparky66wv (edited 12-30-2001).]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
Joined: Oct 2000
Posts: 2,723
Likes: 1
Scott35 Offline OP
Broom Pusher and
Member
Hello everyone, Thanks for all the replies!!!

Been REALLY busy this week, so please excuse the delayed response[s] on my side [Linked Image]

I printed some of this thread and presented as much info to the guy who brought this whole thing "to light" [the person who mentioned all this stuff to me].
I'll print this new stuff, plus what has been added to the redundant threads going in the MHE and IAEI forums, mainly because even after presenting all kinds of information, the guy is still going on what the other dude said only [with no regards to the "what-if's", "why's" and "what-not's" included].

My preferences to pre-twisting are primarily to get a solid and tight splice, which doesn't seem quite right [to me] without pre-twisting ... but that's just my over analysis nature [Linked Image]
The other is just like what others have mentioned - the hot wire springing out of the wirenut and ground faulting... in your face!

It's not a real major concern 100% of the time for me, as I opt to kill circuits unless they just absolutely have to be live - even then you have the possibility of barbecuing someones PC power supply, etc. with open common grounded conductors [AKA open neutrals]. Nevertheless, if the common opens, the PC reboots - and that user loses all the work from since the last save was done [if saves are done!]. If lighting circuits, then the lights go down and such other chaos
[should be Kaos...agents [Linked Image]].

In the multifloor buildings, ground faulting the 277 VAC lighting branch circuits runs the risk of tripping the GFPE main breaker - then EVERYONE is pissed!!! [excuse the language].
The job I have been on over the last few weeks is the typical remodel / T.I. office space project, and is in a 12 story building.
When the original walls were demo'ed, there was a couple of Electricians on-site to "attempt" to stay ahead of the demo monsters, killing as much as they could.

One very anxious demo guy decided to knock a wall down which had "a,b" switches for the 277 VAC lighting in one small office. From what I heard, just as soon as this guy's sledge hammer broke the 4s box loose from the steel studs, the circuit ground faulted [a very sparky one, as from the looks of the effected 4s box]. That tripped the GFPE main and the whole building went down.

Sounds fun, doesn't it? [Linked Image]

I guess the only things heard were the popping ground faults, the sounds of people asking "what happened to the lights?", then the E-Power's diesel prime mover starting!!

For the tape deal, that one is really silly! The wirenut / pre-twist situation has merit, but the taping of Recepts / Switches just sounds kooky!

Once again, thanks to everyone for the responses!!!

Scott. SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
Virgil,

Unless a post ends in Flames or is definitely giving out very poor information safety-wise it is not removed. I don't remember anything like that with this thread, do you?

There may be a glitch going on here. I see that the Forum control panel has some options for some debugging but I don't know anything about them. I think that if the post was removed it would not show up in the search results.

Bill


Bill
Joined: Oct 2000
Posts: 2,749
Member
Bill and Virgil:

Yes, I remebmer a thread that was on the Violations Forum here that I moderate, and I probably deleted it trying to clean up a little.

It was very similar to this one, and I remember that Bill posted a few wirenuts that were green in color with holes in the top.

Just to add more here how about this "RED" wirenut on the EGC's?

[Linked Image from joetedesco.com]


Joe Tedesco, NEC Consultant
Page 2 of 3 1 2 3

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5