Bad Neutrals & Wire Nut question

I spend a few hours each working at a local Home Depot - Electrical Dept.
All too often, customers come by with the same problem - freshly-installed
(anywhere from 1-6 mths ago) burned out light bulbs. Bulbs are replaced - time goes by and the newly installed ones blow out.
Other than surges (we are in Florida), what is the cause of excessive voltage (or what else will do it??) that will "pop" light bulbs??
Another posting on a different subject suggested bad neutrals.
New subject:
While talking about bad neutrals, does the Code say that wires MUST be twisted first before wire nuts are applied?* Packages of wire nuts sold at HD say that twisting is recommended but not required.
*In my own home, about 8-9 years after original installation, #6 and a #12 had been wired together in a 'J' box serving an oven. Oven quite working. Breaker OK. Found wires in J box standing side-by-side, literally, not twisted. Wire nut had melted away. Here is a case where they should have been twisted. However, I notice that here in FL, electricians simply twist on the nut thus expecting a good bond.
Wayne
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wrote:

In the Ft Myers area you will see the voltage cruising around 124-125 volts most of the time. That is tough on light bulbs.
:

Ideal and other manufacturers do not require twisting. If the wires are properly inserted they will be totally encapsulated in the wirenut spring. If the twist is not very concentric and tight you might actually make the connection worse.
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In my "in home" experience with the house with loads of DIY wiring by the former owner, twisting the wires before putting on the wire nut is definitely counter productive.
One joint in a J-box holding up a ceiling fan opened up. It took me some time to figure that out (who would figure that a bunch of wires twisted together under a wirenut would OPEN.)
That was 7 years ago. I have done all kinds of wiring in the place since (including re-wiring a bunch of J-boxes) and I just poke the wires into the wirenut and THEN start twisting. No failures (none expected) and one the occasion I have to undo a connection it's somewhat less messy than the "doubly twisted" connections.
Of course, the wirenut does end up twisting the wires together.
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at
have
twist
there are a lot of electrical workers, and few electricians. Difference is craftsmanship. I have never twisted wires before inserting into a wire nut. When I am done the wires are twisted together. That is just the way I was taught 30 + years ago.
Your description of a #6 and a #12 tied together on the surface sounds seriously wrong. If the over current device is set for the #6 wire or more than 20 amps then the #12 wire is seriously under protected..... Fire insurance paid up? This description sound about right when inexperienced folks are doing work that they have no business doing. Please have someone trace down the 6 and 12 and verify the load locations and overcurrent devices before trouble arrives at your front door.
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Sorry if I misled. #6, properly protected from main service to the J box. The oven's feed was a #12. Here is where the 6 and 12 were "nutted" together.
Wayne

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I'm guessing the oven was changed from electric to gas, In which case it should be on a 20amp breaker max, with one of the phase conductors converted to a neutral. Tapping anything as large as a #6 should really be done with a split bolt and rubber tape. I never did like those big blues.
John

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hi sqlit.. He said the #6 was for his oven.. can't you use #12 as a drop? depending to what.. Even though #6 is good for 60 amp.. isn't that alot for an oven? don't you guys have inspectors that pass by every house before the are built?
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The wires must be twisted to make firm contact with each other. Then the wire nut is twisted on to make more electrical contacts between wires. You need not twist wires together before putting the wire nut on. The wire nut can twist those wires together. But when you are done, and if you remove the wire nut, then those wires must be twisted together sufficiently to remain connected - without wire nut.
These pictures and descriptions may provide useful additional information: http://www.inspect-ny.com/aluminum/piclib02.htm
If the wiring is aluminum and not properly twisted together, then this is a serious and potential fire hazard. Copper wire tends to be more forgiving. But still not forgiving enough that wire is not twisted together.
"Wayne G. Dengel" wrote:

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w_tom wrote:

I seldom twist wires and the wirenut doesn't necessarily twist them.
I do use wirenuts with 'live springs'. The springs deform over the wires and make more contact and, I think, keep the connection tighter. When the wirenut is removed you can see the spring has been deformed. At least some of the wirenuts made by Buchanan and 3M have live springs. At least some of the wirenuts made by Ideal don't.
Bud--
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Some numbers. An incandescent light bulb running at about 127 volts will burn out twice as fast as that bulb at 120 volts. Will burn out about three times as fast at 130 volts.
Some light bulbs suspended from those new composite joists tend to suffer more from vibration. If the basement light is on and kids are running upstairs, then the hot filament will tend to fail more frequently.
Bad neutrals would create premature bulb failure IF the neutral wire failure causes a voltage increase - such as when a 120 volt heavy appliance on the other side of 240 volts attempts to push more current through a poorly connected neutral wire.
"Wayne G. Dengel" wrote:

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Hey Tom!
Interesting numbers re lamp failures at different voltages.
Main problems with blowing lamps that I have found isn't caused by loose wire nuts....its caused by loose neutrals on the neutral bar in the service panel.
Fred

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On Thu, 20 Oct 2005 13:33:18 -0400, w_tom wrote:

Lamp failure goes something like the 12th power of voltage. Given that, 127V ( (127/120)^12) is about 2x, and 130V is about 2.6x. If high voltage is suspected, buy 130V bulbs. They are available.

Funny thing; I just had new "hardwwod" (bamboo, actually) installed on the first floor. I went down into the basement and one of the lights went. No, the fillament was fine, but the constant banging from the pneumatic flooring stapler backed it out of the socket! ;-/

...or an intermittent (which should be obvious).
--
Keith


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Wire nut installed on straight wires, then twisted until the wires make 3 wraps behind the nut. YMMV
--
Anthony

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On Sat, 22 Oct 2005 15:15:24 +0000, Anthony wrote:

That's what I do (twist the crap outta them). I always wonder about wire nuts and stranded wire though.
--
Keith



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Always use ferrules on stranded wire at any terminal, especially if you are wire nutting them.
--
Anthony

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