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eHam Forums => Misc => Topic started by: TANAKASAN on January 07, 2013, 12:40:19 AM



Title: Wire Nuts
Post by: TANAKASAN on January 07, 2013, 12:40:19 AM
Nothing to do with Ham Radio but I'm curious about something. Over on the European side of the pond if we need to join two mains cables behind a wall then either we use a junction box with terminals or we use something referred to as a 'chocolate block' connector, see https://www.europaspares.com/images/14552/1.jpg

In the USA and Canada something called wire nuts seem to be the norm, looking like the cap on a toothpaste tube they just appear to twist on. Are these devices secure and what happens if the cable is pulled? I'm also interested in the current carrying capacity of the connection with just a twist connection.

My personal preference is to use a junction box which clamps the cable at the insulation and, separately, makes the electrical connection but I'm a belt and braces kinda guy.

Tanakasan


Title: RE: Wire Nuts
Post by: K1CJS on January 07, 2013, 04:16:58 AM
Any wire connections done here on this side of the pond are required to be in junction boxes with appropriate strain relief incorporated in the box itself.  Boxes cannot be hidden, either.  For solid conductors, wire nuts provide excellent connections, for stranded wire, not so much, but the connections are still good. 

Since the individual wire nuts are cone shaped, the more they're twisted on, the tighter the conductors are joined.  Of course, it's possible to overdo it, but in general, wire nuts do what they're supposed to do, and do it well enough.


Title: RE: Wire Nuts
Post by: W1JKA on January 07, 2013, 04:33:14 AM
    I can't comment on the chocolate box connectors but as far as wire nuts go they as you say look like toothpaste cap covers,come in various sizes to accommodate different gauge wire sizes.They usually have either a female thread insert or a coil spring inside to compress the twisted wire ends together when twisted on.Most generally used in household 120-240v wiring applications/installation allowed with national and/or local electrical wiring codes.
    They must be used in a static environment where there is NO chance of pull or strain as there is a chance of the wires themselves or wires and inserts pulling out of plastic cap and sometimes even the plastic cap itself splitting open.Be aware that theses slightly off spec and cheaper name brand nuts offered by the big box stores in the U.S  have thinner and cheaper plastic and less rugged inserts.Buy full spec name brands from reputable electrical supply vendors.


Title: RE: Wire Nuts
Post by: KE3WD on January 07, 2013, 05:56:00 AM
And, while they may look like toothpaste caps, the materials used in construction are much more reliable and robust than the materials used to make a common toothpaste cap. 

Inside the composite (plastic) of the wirenut itself there is a conductive threading, as mentioned, it is shaped like an inverse cone and threaded itself such that the more the wirenut is tightened down on two previously and rather lightly twisted wires, the more those wires are forced inwards towards the decreasing ID.  Makes for a rather robust connection and code here requires that such connections should be implemented inside a strain relieved box. 

The wirenut design is robust and time proven. 

After all, we are not experiencing inordinate amounts of electrical fires on this side of the pond due to poor connections...


73


Title: RE: Wire Nuts
Post by: TANAKASAN on January 07, 2013, 06:11:08 AM
Ah! Never having seen one of the wee beasties I didn't know about the metal insert that clamps the wires. So, with the requirement to strain relieve the connections inside a metal box things are a lot safer than they first appear.

Thanks!

Tanakasan


Title: RE: Wire Nuts
Post by: KD0REQ on January 07, 2013, 08:57:31 AM
the National Electric Code for North America says you have to use pliers to mechanically twist the bare wires together before using wire nuts... said twist to go down the insulation at least two turns.

there are plenty of connections inside walls (hopefully inside junction boxes with a wrap or three of PVC electrical tape for moisture protection, although you can probably knock out the walls in any house and find "blind connections" with no box, sometimes with no wire nuts!) that have not been twisted.  you can usually find them by lights that blink randomly, or dim when the furnace goes on.  sometimes they are found when the fire marshal is inspecting the scene.

Euro barrier blocks would not cut it here for line power.  there are scurvy spring-loaded backstab (spring leaf friction connector) blocks that somehow got UL certified, and I believe them to be no more reliable than backstab wiring devices, which arc and gouge the wire and usually wires fall out when you replace them with reliable screw fastened devices.  I like the Euros for LV work, but if you're a believer in that last quarter turn of the screwdriver, you can twist the terminals off the mounting strips in between.  I still like good old Cinch/Beau phenolic screw barrier blocks for thier ruggedness.

the gold standard wire nut is from Ideal, although 3M and Buchanan also have their adherents.

the standard is... if the wire slightly deforms and is held tight by the connection, without creating a fracture point, it's a good connection.  officially, if it isn't gas tight, it probably won't meet code.


Title: RE: Wire Nuts
Post by: K8AXW on January 07, 2013, 09:04:37 AM
CJS: I concur!  To use the "chocolate bar" method of connecting wires behind my wall board would leave me sleepless for the rest of my life!

CJS covered it very well.  There is a new (to me) product out now whereas you bring out the wiring in a box and stuff the ends into a junction block.  I have no idea if they are UL approved or meet state code.  Just a FWIW.


Title: RE: Wire Nuts
Post by: G3RZP on January 07, 2013, 09:22:41 AM
I have seen older wirenuts in ceramic, but I suppose that's  more expensive.


Title: RE: Wire Nuts
Post by: W9GB on January 07, 2013, 04:22:34 PM
The 3M ScotchLok wire nuts are found in 120/240 VAC residential wiring.
http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtUnY_vMxmGev7qe17zHvTSevTSeSSSSSS--

The 3M Highland connector is common inside Lighting Fixtures.
http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UuZjcFSLXTtn8Ta4xs6EVuQEcuZgVs6EVs6E666666--


Title: RE: Wire Nuts
Post by: WB2WIK on January 07, 2013, 06:28:23 PM
Wire nuts work well, but they are manly things.  If you're a female electrician, there can be problems. ;)


Title: RE: Wire Nuts
Post by: KE4DRN on January 07, 2013, 09:19:26 PM
hi

these connectors from Tyco are available but not popular

http://www.te.com/catalog/cinf/en/c/11621/1394

73 james


Title: RE: Wire Nuts
Post by: KD0REQ on January 09, 2013, 10:33:22 AM
general rule about Tyco (fka Amp)... the connectors may be inexpensive, may not be,  but there is almost always a tool involved, and the usual price is $280.


Title: RE: Wire Nuts
Post by: KE3WD on January 09, 2013, 02:16:31 PM
And, those type of insulation displacement connectors are not to be used on household mains wiring, inside junction boxes. 


Title: RE: Wire Nuts
Post by: KE4DRN on January 09, 2013, 04:44:41 PM
hi,

No special tools required, just slip joint pliers and screwdriver.
the two screws secure the strain relief not the connector,
that snaps shut with locking plate.

These connectors are use in modular home construction and are insulating devices equivalent to NM cable and can be installed in accordance with Section 334.40(B), so if is being used for rewiring in existing building, it can be concealed and finished.

http://www.ampnetconnect.com/product_groups.asp?grp_id=2307&path=0,2299

I am not a licensed electrician and local codes may or may not allow them.

73 james


Title: RE: Wire Nuts
Post by: AA4HA on January 10, 2013, 05:01:25 AM
Wire nuts work well, but they are manly things.  If you're a female electrician, there can be problems. ;)
That is why it is best to tighten them with a pair of pliers until they make a squeaking noise.  :D


Title: RE: Wire Nuts
Post by: N9KTW on January 10, 2013, 03:24:25 PM
As a Licensed electrical contractor for over 30 years it is a very rare occasion to see a PROPERLY installed wirenut fail or fall off. I was taught as an apprentice that the reason to twist the wires prior to the installation of the wirenut is so that if it needed to be removed on a live circuit the splice wouldnt come apart creating an additional hazard of live wires fannining out in all directions.

I have used more than a few wirenuts in the shack to connect equipment to the power supply when there isnt enough room on the binding post ( being careful of course to watch the gauge of the initial lead from the binding post). Never had a failure, beats tape, as it doesnt loosen of get gooey if you need to change things.

Just my "2 cents worth" .


73 de Howard, N9KTW


Title: RE: Wire Nuts
Post by: KE3WD on January 10, 2013, 03:45:46 PM
Well, when it comes to good ole fashion American Git-R-Done, the wirenut can and indeed does show up being pressed into service for all kinds of connections other than household 120 wiring. 

Those tiny gauge wirenuts come in handy on low voltage stuff, speaker wiring, too.

And, this old ham as used a pair of wirenuts to extend his ladderline to the antenna, outdoors, no less, you know how it works, it was temporary, at least that's what I said at the time, they stayed out there several winters before I had to address the issue and then it turned out to be the solder joints up at the feedpoint had crapped out, those two weathered wirenut connections were still going fine. 


73


Title: RE: Wire Nuts
Post by: K0JEG on January 13, 2013, 10:21:47 AM
Just don't use them to make a "splitter" for your Cable TV.



Title: RE: Wire Nuts
Post by: KE3WD on January 13, 2013, 12:33:16 PM
Well, I have actually used wirenuts to join to pieces of coax together on Field Day. 

Likely there was an impedance bump, but my antenna tuner did not seem to mind. 

The more fun was had listening to all the hams declaring such to be wrong and impossible, shouldn't be done, wouldn't work, while every one of 'em was standing there watching me rack up CW contacts and logging same.  Of course, non of those knowledgeable chaps could even copy the CW contest speeds being demonstrated right in front of their eyes...

I remember viewing a webpage of a Brit amateur who used hardline as feedline to his rather elaborate topband antenna setups, he spliced hardline together in much the same way, big ugly twist and solder connections, after which he would twist them to point upwards and plop a clear plastic two liter soda bottle overtop as his protection from the elements.  Looked nasty, but then there were all these contacts he routinely made on topband, complete with the great signal reports. 

73


Title: RE: Wire Nuts
Post by: KH6DC on January 13, 2013, 09:56:57 PM
All electrical connections behind the walls are in either metal or plastic junction boxes and connected wth wire nuts or wing nuts.  Strain relief in a form of clamps are used plus I pigtail the grounding wire to the box (if metal).


Title: RE: Wire Nuts
Post by: KE3WD on January 14, 2013, 12:11:29 PM
I once tore into the wall of an old house up in Pennsylvania and found ZIPCORD inside, being used to power ceiling light and two receptacles. 

The zipcord was the old rubberized stuff, stiff as a board and cracked all over, yet there obviously had never been a fire. 

Of course, that prompted me to do a total rewire of the property.  I also found romex from the old fusebox that was only in the visible areas of the basement, up inside the walls it magically turned into pin and tube, no wirenuts, big twist connects covered in friction tape.  What a mess.

It constantly amazes me the amount of misuse and abuse our electric system can take without mishap, seeing things like this.  But I'm sure that not all enjoyed the luck of the draw, as it were.  Have seen many an electrical fire as well.  The old buildings in the northeastern part of the country seem to be able to show you anything and everything.  A lot of it just plain wrong. 


73


Title: RE: Wire Nuts
Post by: K1CJS on January 15, 2013, 03:43:29 AM
...I also found romex from the old fusebox that was only in the visible areas of the basement, up inside the walls it magically turned into pin and tube, no wirenuts, big twist connects covered in friction tape.  What a mess....

...The old buildings in the northeastern part of the country seem to be able to show you anything and everything.  A lot of it just plain wrong.

Taking into account the age of some of those buildings, some of that wiring was standard practice back then.  Not the zipcord, but pin and tube converted to old gutta percha 'romex'.  Also, the standard way of splicing was to twist the wires together and use friction tape--plenty of it.  You've got to remember that this was before even those old porcelain 'twist ons'--the precursor to wire nuts.

I agree that old wiring like that ought to be replaced when come across when additions or alterations are made, but on the other hand, if it isn't disturbed, there is no reason that it shouldn't continue to do what it was intended to do.  You've got to remember that back then things were done to last--and with materials that would outlast the newer, more modern materials that have been used since then.


Title: RE: Wire Nuts
Post by: KE3WD on January 15, 2013, 06:38:54 AM
Yes, I knew that what I found was once standard practice as regards the pin and tube conversion. 


What I was trying to highlight is that, even though this situation had been allowed to stay there way past its "freshness due date" and all of it was dry, crumbling, tape and cloth covered insulation, it was still working in there all those years, and, apparently hadn't burnt the place down.  Grandpa's generation of electricians knew quite a bit. 


73


Title: RE: Wire Nuts
Post by: KD0REQ on January 15, 2013, 09:07:39 AM
>> You've got to remember that back then things were done to last--and with materials that would outlast the newer, more modern materials that have been used since then

I don't buy it.  the KnT in my folks' house was 18 gauge Copperweld.  no way in heck that stuff is good for 15 amps.  wsn't then, isn't now.  I went whaling on that stuff at every opportunity, and much of it had the gutta-percha or crackly rubber coming off at the touch.


Title: RE: Wire Nuts
Post by: K1CJS on January 16, 2013, 03:59:35 AM
Grandpa's generation of electricians knew quite a bit. 

Yes, they certainly did.


Title: RE: Wire Nuts
Post by: AA4PB on January 16, 2013, 06:04:21 AM
Many of the issues you find in old homes are not the result of an electrician. It was usually the result of a homeowner who didn't think about safety doing his own thing. You should see some of the things I've found in old government buildings! For example, a 100 foot + run of #18 zip cord run through an unprotected knockout in a panel and connected directly to a 15A breaker. Guess they ran out of BX cable that day  ;)


Title: RE: Wire Nuts
Post by: KE3WD on January 16, 2013, 09:44:30 AM
Many of the issues you find in old homes are not the result of an electrician. It was usually the result of a homeowner who didn't think about safety doing his own thing. You should see some of the things I've found in old government buildings! For example, a 100 foot + run of #18 zip cord run through an unprotected knockout in a panel and connected directly to a 15A breaker. Guess they ran out of BX cable that day  ;)


I once encountered an entire gummint built office building that was using shared neutrals everywhere. 

They had already remodeled the interior and I was called in to find out what was happening to all the personal computers.  What a mess. 

Place was built back in WWII.   Picked up for a "song" in the 80s to be converted to private use, boy did they buy a pig in a poke.  Cost 'em millions on that attempt at a dynamite deal.

73


Title: RE: Wire Nuts
Post by: K1DA on January 23, 2013, 09:55:47 AM
I've never liked the idea of joining ROUND wire by "compression". Not much surface area between the two conductors.  Every wire nut I have used in my home has been AFTER soldering the wires.  Belt and suspenders. 


Title: RE: Wire Nuts
Post by: K1CJS on January 29, 2013, 05:06:50 AM
I've never liked the idea of joining ROUND wire by "compression". Not much surface area between the two conductors.  Every wire nut I have used in my home has been AFTER soldering the wires.  Belt and suspenders.  

Ah, but you overlook the fact that copper wire is very malleable.  Soft wire like that doesn't stay 'round' when it is compressed, it squashes together.  If you've ever looked at a properly tightened wire nutted connection when the wire nut is removed, you'll find that the wires aren't perfectly round, they ARE squashed together, and the imprint of the coil of the wire nut is present on the outer sides of the wires that were joined together.

As a matter of fact, depending on the solder used, a soldered then wire nutted connection may be a poorer connection than one made without being soldered.  The solder may in fact be harder than the wire and may flow again if the connection is heated, loosening the connection itself.  

Properly joined connections made with wire nuts do not need any other means of joining the wires together.  If that weren't the case, the Underwriters Labs would have never approved the use of wire nuts in the first place.  73!  


Title: RE: Wire Nuts
Post by: G3RZP on January 29, 2013, 09:01:45 AM
I think the pressure on the wires actually leads to some cold welding, as with wire wrapped joints.


Title: RE: Wire Nuts
Post by: KE3WD on January 29, 2013, 10:23:24 AM
Millions of wirenuts in use for several or more decades without solder. 

But there's always going to be someone with a solution in search of a problem...



73


Title: RE: Wire Nuts
Post by: KE4DRN on January 29, 2013, 07:12:43 PM
hi

had a customer in my home depot today, he was from the UK,
he was adding an outside light and selected one of the
Ideal terminal strips, similar to the original post.

http://www.idealindustries.com/media/img/products/oem/product/terminal_strip_437.jpg

I set him up with some pvc boxes and wire nuts.

On the other hand, we get so many more people who want to cut
corners and just bury a splice in the wall and just cover it up with drywall.

73 james


Title: RE: Wire Nuts
Post by: K1CJS on January 30, 2013, 09:25:43 AM
Good point, Peter.  Sometimes it does, especially if the joint carried heavy current and it had been in place for years.


Title: RE: Wire Nuts
Post by: KD0REQ on January 30, 2013, 09:58:32 AM
DRN, that's a Cinch or Beau block by design (Beauchane licensed the design as a second source,) not a Euro screw-against-leaf-against-wire block.  strictly LV stuff or under-chassis stuff in this country.

I am constantly amazed at what folks try to get away with, and how little they look at what's around them.  when we gutted the basement to the blocks and rebuilt it, out of need, I found a blind connection in a closet wall.  oh, it had a box.  but no cover.  no mechanical backup to the wire nuts.  all to run another two feet to an outlet.

the curious thing occurred when we tore up that closet (headers weren't even nailed to the floor joists or the concrete, of course.)  there were 12 feet of Romex coiled and jammed and twisted in the ceiling, and THEN it came down to where the blind connection was.

never underestimate the power of "hold my beer, and watch this!"


Title: RE: Wire Nuts
Post by: KE4DRN on January 30, 2013, 02:21:49 PM
REQ, what gets us concerned is the people who want to do it the easy way,
they just don't care about doing it the right way.

"I'm selling the place", etc.  one young couple refused to spend $15 on
a Studor vent for a half bath, they were going to leave the vent pipe open
in the walls.  Just crazy.

Most of these people are educated, yet they want to swap out
a 15a breaker for a 20a because their printer trips the breaker
or remove the arcfault breaker and put a standard breaker in place.

Somebody can make a lot of money if they can image the internals of
the walls of these buildings before a buyer signs the sales contract.

73 james

73 james


Title: RE: Wire Nuts
Post by: K1CJS on January 31, 2013, 04:11:26 AM
You say they're educated, but they're not--not in the ways of building and trade work.  Heck, even back then some of the 'experts' at electrical work weren't.  Some had a novel voltage tester--they stuck their finger in a light socket to see if the juice was on!


Title: RE: Wire Nuts
Post by: K3GM on January 31, 2013, 07:53:31 AM
.....Most of these people are educated, yet they want to swap out
a 15a breaker for a 20a because their printer trips the breaker
or remove the arcfault breaker and put a standard breaker in place......
I work in a corporation filled with EE, ME and Physics Phd's and "Fellows", of which I am neither.  I am constantly dumbfounded by their lack of Basic Common Sense.  Perhaps this should be a mandatory course offering at the colleges that hatch these poindexters.


Title: RE: Wire Nuts
Post by: KD0REQ on January 31, 2013, 08:51:40 AM
james, why spend $15 more when the home inspector can kill your house sale?  that's the way to sell it.

baseline is this... and it even applies here to wormwarmer grounds and low-hanging hatsnatchers... it is plain dumb to hack something three times when doing it right the first time costs half that and doesn't need to be done again.  do some basic research on the wacky wacky webbiepoo and find out what the present standards are.  then if you can't figure out how to do that, learn.