Crimp-and-tape vs. wirenuts -- for hots?

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I am redoing some wiring in our house that involves breaking and remaking some original connections -- ripping out and replacing boxes by larger (e.g., two-gang by three-gang). I find that in some cases all the conductors of the same color have been connected using crimps that have then been taped over -- even the hots. Is this kosher? Surely wirenuts provide better insulation than the tape. There could be 220/240 volts between conductors in some boxes because there are Edison circuits involved.
Should I use wirenuts for the reconnections? Crimps and tape take up less room.
And, while I think of it, is it OK to have circuits fed from different breakers in the same box (e.g., outlet and light switch)? One could assume that since the one circuit is dead (switched off at the panel), the other is too.
Perce
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Addressing the connection method: When I think of crimps, I think of the type that already have a plastic sleeve over a metal interior. However, I *have* seen a type that's just a metal sleeve. As far as I know, they are intended only for joining bare ground wires.
Someone will stumble along here and claim otherwise, but I think electrical tape is for slobs and hacks who don't know how to make a secure connection, so they cover things up with tape to hide their incompetence. It also leaves things gummy. When I want to rewire something, my definition doesn't include wiping gunk off my fingers constantly because some monkey went nuts with tape.
I once asked a local inspector and was told it was perfectly legal to use crimps for house wiring, and was told that it WAS. There are two caveats:
1) You must use a crimp tool that actually shapes the crimp properly. You won't find such a tool at Home Depot or Lowe's. It'll take some effort. It requires a channel for the crimp to sit in, and a tooth-like prong on the opposite jaw. The tooth almost creates a hole in one side of the crimp.
2) If wires might need to be disassembled later, and they're already short, cutting off an old crimp will obviously make them even shorter. Use wire nuts in these situations. Have several sizes on hand.
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[...]
Wire nuts are perfectly fine; crimps aren't unless they're made properly, and - no offense intended - asking the question shows that you don't know how to make them properly.

It's "OK" in the sense that it is permitted by the NEC, although in my opinion it should not be -- for exactly the reason you cite. It would be a good idea to write a warning with a Sharpie on the inside of the cover plate.

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Regards,
Doug Miller (alphageek at milmac dot com)
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On 07/20/07 03:24 pm Doug Miller wrote:

I have a Gardner-Bender stripping/crimping/etc. tool that AFAIK is meant for this job, and I believe I know how to use it. Asking whether it's OK to do something has nothing to do, IMO, with knowing how to do it. There are many possibilities:
1. I know it's OK and know how to do it.
2. I know it's OK but don't know how to do it.
3. I don't know whether it's OK and wouldn't know how even if it is OK.
4. I don't know whether it's OK but know how to do it.
I believe I fall into the last category.
Actually I suppose there are yet other possibilities:
5. I know it's not OK but know how to do it and will do it anyway.
6. I haven't a clue but will do it wrong even if it would be OK if I did it right....

Good idea.
Perce
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Sure its kosher when its done right. BTW, high voltage, high current cables - that is, thousands of volts and thousands of amps - use crimp (compression) connectors.
Surely wirenuts

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On 07/20/07 11:41 pm ** Frank ** wrote:

It wasn't so much the crimping I was questioning as the two or three layers of insulation tape vs. however many mm of insulation provided by a wirenut.
Perce
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wrote:

Of course more insulation is better, but r
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wrote:

More insulation is better, but remember that the splice is usually tucked safely in the box
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Percival P. Cassidy wrote:

Tape is OK. I would use more that 3 layers. Be careful of points and edges that can poke through the tape. It has to be listed electrical tape.
The crimps also have to be listed for purpose - including wire size and number of wires, stranded/solid, and voltage for insulated crimps.
-- bud--
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One more time: The tape is sloppy, and if the crimp is done right, there is absolutely no need for it.
This company makes the best crimps you can buy: http://www.panduit.com/search/search_results.asp?NP00001+151&Ne=1&region=USA&Nu=P_RollupKey
On that page, you'll see a link to a pdf file which discusses proper crimping tools and techniques.
Although you can order directly from the company, there may also be an industrial supply dealer near you that sells their products.
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On 07/21/07 08:39 am JoeSpareBedroom wrote:

These are the plain copper cylinders (more or less) that are crimped onto the wires. As supplied, they have no insulation, so obviously if they are used on hots or neutrals they need to be insulated afterwards. What would you use other than tape -- or shrinkwrap, I guess?
Perce
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Since the wrong kind of crimps were used, I would cut them out and change them to insulated crimps. If you have the wrong connectors, you don't use them and try and make them right. You stop the work until you have the right thing. A cob job might be appropriate when making toast, but not when wiring a house (or car, boat, or anything else).
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JoeSpareBedroom wrote:

On what is that conclusion based?
I would cut them out and change

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Bare copper cylinders need to be insulated after they're installed, right? One method would involve tape, which is sloppy and amateurish, and I don't care whose grandpappy did it and got away with it. The other method involves heat shrink tubing, which is miraculous stuff, but to use it **correctly**, you should apply heat to all sides of the tubing. Not so easy with short wires in a box.
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JoeSpareBedroom wrote:

Your preference against it doesn't make it "wrong."
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It most certainly does. With wiring, only perfection is acceptable. Tape doesn't even come close.
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JoeSpareBedroom wrote:

And you think wirenuts are "perfection?" Good luck with that.
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No. I didn't say that. Wire nuts may be the only choice in a cramped box where the wires are already too short for working with a crimper. But, crimps are always the best way, when it's possible to use them.
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JoeSpareBedroom wrote:
...

"Perfection" is defined for practical purposes by the NEC. If it accepts a practice, that's perfect enough...
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I suspect it accepts the practice because wire nuts are faster to apply than crimps, and professionals like it that way.
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