why wire nuts for mains connection?

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rif

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Joined 2003
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Just curious

Why are wire nuts used, at least in the US, in junction boxes, switch boxes, outlet boxes, etc. for ac mains connections? why not crimp connectors as we use in our chassis?

I find them frustrating, especially when tying together 3 wires.
 
Agree, I have a section box with my collection of wire nuts. They come in many sizes. If you are tying three 12ga wires together, you need a nut designed for it.

They are cheap, reliable, installed without tools, and easily undone for changes or troubleshooting.


I find it baffling when a customer brings me an amp, where the wires to the speaker plug onto the board with a molex connector, yet they leave the connector on the board and cut the wires a couple inches out. ARRRGGGHHH! Just unplug the thing... I see wire nuts like that. A crimp is a splice, while a wire nut is a connector.
 

rif

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Disabled Account
Joined 2010
Yes,

that's what we called screwits.

http://www.theiet.org/Forums/Forum/messageview.cfm?catid=226&threadid=3659

Apparently they had problems with earths becoming disconnected and live cables on equipment vibrating loose and touching down making metalwork live on machines.
The ones we had were yellow with little plastic wings on the sides. (Provided by the company at the time)
We used them for years until the sudden change.

Pronounced "screw-it" I don't even remember where the name came from :D.

Regards
M. Gregg
 
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Disabled Account
Joined 2010
In the UK,

They advise not using junction boxes..if they are used they should be accessible..:rolleyes:

It causes a few problems with the definition on what is accessible. Under floor boards is not really considered accessible because
people put laminate flooring down and this changes the situation..

So things like this have been used..
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However obviously its dependant on the standards and where its being fitted etc.
I have seen things like this:
An externally hosted image should be here but it was not working when we last tested it.


However the accessibility is the issue.

Years ago people used to just push strip connectors tapped up into ceiling cavities to fit lights, however its not allowed now.

Central heating in houses uses its own type of box like this:



Obviously the current rating etc has to be taken into account.

The old long time used was this:


But if the box is not accessible its supposed to be a permanent joint which makes this a bit difficult to use now..so soldered or crimped was the idea.
I hope this is of help..there are fittings for ponds outside it goes on (waterproof)..etc
In the UK fittings have whats called an IP rating depending on the type of environment its going to be used in.
Ie splash proof,drip proof, flame proof etc

The above are domestic, on machines we use metal boxes with clip in connectors and gasket sealed lids. This allows for conduit or SWA (steel wire armoured) connectors etc. Like this:


images



I feel like I'm droning on so I'll stop..:D
Here is an example of a UK supplier so you can have a search..

http://www.neweysonline.co.uk/aluminium+box/q01.r10.1/Search.raction

( I have no connection its just for interest)

Regards
M. Gregg
 
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In Canada, professional electricians sometimes do use crimp connections; I've seen 'em plenty of times when working on house wiring. Specialized crimper to compress the metal 'sleeve' over the wires and an integral plastic cover over. Quick and cheap but not reversible.

We had all kinds of problems when aluminum wiring was the 'latest and greatest' for a while - special wire nuts and compound are needed to connect Al properly.

BTW, the electrical code anywhere in Canada that I've checked doesn't allow junction boxes in 'inaccessible' areas....no boxes buried in walls or under flooring are allowed. Boxes in open ceiling areas in basements or attics are allowed, and this can be a major hassle if you want to 'finish' a basement into a living space and put up drywall on the walls and ceilings.

I was in my local electronic supply place the other day, and on the counter they had a display of 'clamp'-style wire connectors which supposedly will replace wire nuts...which I doubt, since they were dollars/clamp.

My experience with UK electrical standards is from India...I kinda miss the sizzling and sparking that let me know when the electricity was 'on again' in the neighbourhood.:)
 
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Yuck, wire nuts are awful. Don't know why we still use them or why they are still allowed. I've recently seen the crimped wires here in the USA, seems better. I prefer the terminal blocks used in Europe. Not as fast, for sure, but so much more secure.
 
I was taught to tightly twist the wire bundle with electrical pliers, trim them to ensure that no uninsulated strands would be outside the nut, then add two wraps of electrical tape around the base of the wirenut and onto the wire bundle wrapped in the direction the nut tightens. I've never had a connection issue using this technique.
 
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