Number of wires in a wire nut?

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  #1  
Old 10-27-05, 04:17 AM
J
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Number of wires in a wire nut?

In a junction box in my kitchen ceiling I will have the feed and 3 circuits. I'm faced with twisting 4 wires into each wire nut. Is this the best way, or would it be better(safer?) to use a pigtail so that each wire nut would have only 3 wires to twist. Twisting 4 wires together seems like a stretch, and I'm using 12/2 w ground for the feed and for each circuit.

Could some one give me the ground rules for twisting wires (and mixing sizes) inside wire nuts.

Thanks,

John
 
  #2  
Old 10-27-05, 07:00 AM
ollie
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John
There are no rules. The manufacture of the wire nuts will tell you how many and what size wires can be used with any given size wire nut. You have to follow his directions. The rules should be printed on the package. You should be able to find a wire nut for your job.
Ollie
 
  #3  
Old 10-27-05, 07:09 AM
R
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Putting four #12's in a wire nut is very common and is easily done with an experienced hand. However, it is a not easily done by those who dont have the hand strenth or experience. I have seen so many poor connections by homeowners when dealing with more than 3 wires I would like you to consider
using push in connectors. These are not the same design as the push in connectors on switches and receptacles that are known for bad or poor connections. They essentially take the place of a wire nut and you strip the wire in the same manner according to the wire guage on the push connector. Then you simply push them into the provided ports on the connector.
Also use a junction box that has the required volume for 4 cables with ground. You'll need 20.25 cubic inches minimum if you use a plastic jb like a carlon. Home Depot was carrying the push connectors last time I checked. Or you can get them at an electrical supply or order online.

Example: http://www.goodmart.com/products/ele..._connector.htm

These are bulk quantities so you will need to find a source that allows you to buy just what you need, if you choose to use them.
 
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Old 10-27-05, 07:24 AM
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The rules for mixing wire sizes are set by the manufacturer and the testing lab that tests the design. If you look at a package of wire connectors of any sort, you will find lists of the allowed mix of wire sizes. Some companies will list complete tables of allowed connections online. You can find wirenuts which will take rather more than 4 wires, although these become a serious pain to work with.

As far as making up these connections, here is what I do.

1) Practise. Get some wire nuts and some scraps of wire, and practice making up splices and then taking them apart to see if they were solid. Do this sitting comfortably at a table, and make a bunch of them. This will help you get the feel for a proper splice.

2) Pretwisting is _not_ necessarily your friend. This is somewhat controversial, so be sure to look at other opinions. IMHO pretwisting itself does not make for a better electrical connection. When you look at some packages of wire-nuts, you will see instructions such as 'pretwisting not required', or even 'do not pretwist'.

However pretwisting does have a significant benefit: it holds the bundle of wires together while you apply the wire-nut. The most common failure that I find is that one wire gets pushed out of the splice as the wire-nut is applied, and pretwisting will prevent this. For larger bundles of wires, what I do is to get all of the wires aligned, and then tape them together with electrical tape below the splice (1-2" from the end). This holds the wires together and makes sure that they all enter the wire-nut, but doesn't risk damaging the conductors from trying to form a big twisted up mass of wires. I then screw on the wire-nut and make sure that it has clamped down well.

3) Alternative wire nuts. The problem with wire-nuts is that it is hard to inspect the connection, so you need to be certain that you've gotten it right. There are other splice techniques that are easier to inspect. As an example, you can use 'set screw wire nuts' http://www.idealindustries.com/IDEAL...1?OpenDocument

These are small brass ferrules with screws in the side. You slide the wires in, tighten the screw, and then screw on a plastic insulating cap. The benefit is that you can make the splice, see that all of the wires are in place and secure, and only then put on the insulating cover. I use these whenever I am not in a good position to really double check a splice. They are much more expensive that common wire nuts (about $1 each rather than $0.05 each), but this is not a significant issue if you are a DIYer doing only a couple of splices. http://www.mcmaster.com has these on page 690 in packages of 10.

-Jon
 
  #5  
Old 10-27-05, 11:42 AM
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Remember that the wire nut dosnt make the connection, it holds the connection.
You should twist your connection together first, then add the nut. If you just lay wire in the nut and expect the wire nut to do the rest, you may have bad connections down the road.
 
 

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