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'[OT] household wiring connections'
1999\09\19@170413 by Dwayne Reid

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>Why DON'T they solder household connections? Is it because they would not
>be as easily disconnected and reconnected? It seems to me that things would
>be safer,more reliable, and there would be less voltage drop.


Actually, LESS reliable!  Solder has a much higher resistance than copper
which becomes significant at the currents that some household appliances
require.

I actually have come to believe that the spring type wire nuts (Marettes,
Murettes) are FAR more reliable than any other connection I have used in the
past.  They just have to be installed correctly.  I used to do a lot of
electrical work (1 year between high school and college) - we used to use
T&B Sta-Kon crimp splices.  I have since seen many of those splices fail
over a period of 15 years or so because they became loose (copper cold flow,
I think).  I have not seen this happen with a wire nut - the spring
stretches while being tightened and keeps the connection under tension.

Note: I have seen other brands of wire nuts without the spring - I don't use
them and do not know how reliable they are.

dwayne


Dwayne Reid   <spam_OUTdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax

Celebrating 15 years of Engineering Innovation (1984 - 1999)

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1999\09\19@173545 by Michael Barker

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> I actually have come to believe that the spring type wire nuts (Marettes,
> Murettes) are FAR more reliable than any other connection I have used in
the
> past.  They just have to be installed correctly.  I used to do a lot of
> electrical work (1 year between high school and college) - we used to use
> T&B Sta-Kon crimp splices.  I have since seen many of those splices fail
> over a period of 15 years or so because they became loose (copper cold
flow,
> I think).  I have not seen this happen with a wire nut - the spring
> stretches while being tightened and keeps the connection under tension.

I have to agree; in the States, each different type of wire nuts are UL
listed
(not much sure of the reliability of UL) for a certain number of wires at
various
wire gauges.  One in particular that I have used commonly was rated for 2-5
14 gauge, 2-4 12 gauge, and 2-3 10 gauge wires.  As long as the wires were
within the proper number, the wire nuts made a firm hold that could not come
loose.  (These also had the metal spring, which would hold onto the wires by
making grooves in the exposed copper.)  To insure the connection, however,
the wires were twisted together tightly using side cutters and the wire nuts
were mainly used to cover and hold the joint.  If the wires were not twisted
together beforehand, I doubt the connection would be as good.  Plus, this
was with solid copper, not stranded, which my pose a whole different
ballfield.

> Note: I have seen other brands of wire nuts without the spring - I don't
use
> them and do not know how reliable they are.

If they do not have the metal spring, the plastic threads can become warped
or stripped while twisting the nut on the joint, leaving an insecure hold.
(Imagine
trying to screw a plastic screw into a hole in a sheet of metal...)

Regards,

-- Michael

1999\09\19@181816 by Sean H. Breheny

face picon face
Thanks to all who replied on this subject. I guess I will have to try some
experiments to prove this to myself. I have always held the statement "A
properly soldered connection is a _reliable_ connection" in my mind,and its
hard to shake it free :)

I kinda find it hard to believe,too,that an average copper-copper twisted
connection has less resistance than a properly twised-and-then-soldered
one.  Solder may have a higher resistivity,but it seems to me that since it
fills in all the gaps in the connection,there is greater contact area,and
the total resistance is lower.

I also find it kinda hard to believe that wires in a 15 to 20 amp circuit
get hot enough to soften solder significantly. Since the wires are (or
SHOULD be) twisted together before soldering, the combination should be al
least as mechanically strong as if it weren't soldered (unless solder acts
as a lubricant at temperatures permissible in a junction box).

Sean

At 03:02 PM 9/19/99 -0600, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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1999\09\19@184159 by Bob Drzyzgula

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On Sun, Sep 19, 1999 at 05:23:40PM -0700, Michael Barker wrote:
> To insure the connection, however,
> the wires were twisted together tightly using side cutters and the wire nuts
> were mainly used to cover and hold the joint.  If the wires were not twisted
> together beforehand, I doubt the connection would be as good.

I worked as an electrician on a construction job for
a Summer (actually, as a helper, but I had tools and
could think, so they gave *me* a helper and had me
work independantly), and we used wire nuts extensively.
There was one thing that was drilled into me, though:
Do *not* pre-twist the wires. The spring will cut into
and hold the wires much more securely if the full side of
the wire touches the springs. You want the force of the
compression created by twisting the wire nut down onto
the wires to be what holds the wires together, not a
relatively loose crimp from a pair of pliers.

--Bob

--
============================================================
Bob Drzyzgula                             It's not a problem
.....bobKILLspamspam.....drzyzgula.org                until something bad happens
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1999\09\19@184810 by Mike Keitz

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On Sun, 19 Sep 1999 17:23:40 -0700 Michael Barker
<EraseMEmeb8208spam_OUTspamTakeThisOuTRITVAX.ISC.RIT.EDU> writes:
>  As long as the
> wires were
> within the proper number, the wire nuts made a firm hold that could
> not come
> loose.

I've done a lot of wiring and found that, as with everything else, wire
nuts have to be used properly and the user should be aware of their
limits.  But done properly they will make a quick, relaiable connection.

The most vital precaution to using wire nuts is to align the wires so the
ends are in the same place before putting the nut on.  If one is shorter
or longer than the others it will cause one or more wires to be loose.
Also, connecting more than 3 wires at a time or wires of widely different
sizes with a wire nut is difficult.  It is essential to select the proper
nut for the number and size of wires involved.  Pull on the nut and wires
after installing it to test for loose wires.


(These also had the metal spring, which would hold onto the
> wires by
> making grooves in the exposed copper.)  To insure the connection,
> however,
> the wires were twisted together tightly using side cutters and the
> wire nuts
> were mainly used to cover and hold the joint.

I don't like twisting the wires first.  The nut does a lot more than
"cover and hold" a twisted together joint since the wires are being
forced into a conical space as you tighten it.  It's important to twist
the wire nut on tightly enough that it twists the wires for you.  The
insulated part of the wires below the nut should start twisting together
too.  (Hold the wires an inch or so below the nut when tightening).  When
the insulated part of the wires twists together, the nut is tight enough.
Especially in the larger sizes, the type of wire nut with wings on it is
easier to tighten by hand.   You can also grab the outside of the nut
with pliers or use a simple plastic tool made for the purpose to tighten
it.

>   Plus,
> this
> was with solid copper, not stranded, which my pose a whole different
> ballfield.

Stranded is about the same but you have to be careful to get all the
strands into the nut.  Stranded works better with different sizes of wire
in the same nut.

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1999\09\19@190513 by Sean H. Breheny

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At 06:40 PM 9/19/99 -0400, Bob Drzyzgula wrote:
>Do *not* pre-twist the wires. The spring will cut into
>and hold the wires much more securely if the full side of
>the wire touches the springs. You want the force of the
>compression created by twisting the wire nut down onto
>the wires to be what holds the wires together, not a
>relatively loose crimp from a pair of pliers.

This I definately agree with. I have actually done some household
wiring,too (and,no,I didn't solder <G>), and even with my small amount of
experience,I could see that the nuts stayed on better if you didn't twist
the wire first.

Sean


{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
@spam@shb7KILLspamspamcornell.edu ICQ #: 3329174

1999\09\19@224622 by William K. Borsum

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Hi All:
I like wire nuts too.

On the subject of soldering:
Where absolute reliability and low connection resistance is mandated, we
will crimp the wire into a contact, and then add solder to the crimp area.
THEN add physical reinforcement to the wire coming out of the back of the
crimp to keep it from bending.

I've used a lot of crimp terminals and contacts over the years, and have
had good luck--provided I matched the terminal to the wire  and insulation
diameters--AND used the recommended crimping tools (sometimes >$300 for
special contacts).

There are even special crimp-on's designed to fit the "stick the wire in
the hole" type of terminals and provide a solid piece for the screw to
clamp down on.

Solder forms a rigid joint, and as the solder wicks back up the wire a
bit--often under the insulation too--it forms an interface between the
rigid part filled with solder, and the wires.  IF there is any vibration or
bending, it will fail at this point.  There is also metallurgical stuff
going on that can make the joint more brittle as well.   I think
electricians (as opposed to electronic types) have never been trained to
solder, don't have the equipment, use acid core solder, and general y screw
things up--mostly out of ignorance--and occasionally stupidity. Electrical
Codes are intended to supplant thinking on the part of the installers, and
so become somewhat dogmatic--but hard to create a hazardous situation when
followed.  Main emphasis is on FIRE safety--not shock hazard.  Bad joints
can get HOT.

Enjoy
Kelly



William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems
<KILLspamborsumKILLspamspamdascor.com> & <http://www.dascor.com>

1999\09\20@081957 by Harrison Cooper

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IMHO, wire nuts are great for connections that are not going to move
much....at least I hope my house isn't going to move much and if it does, my
electrical connections will be the least of my worries!

Connections that have stress ought to be secured by terminal blocks, rings,
spades, butt connections, soldered...etc.

In as much as the current flow thru household wiring causing enough heat to
melt solder....I'd be more worried about what is pulling that much on a 15
amp circuit to generate that much heat...leading to a fire?

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