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'[OT] Muscle contraction. was: cats! -Reply'
1999\09\15@020829 by Nigel Goodwin

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In message <spam_OUT4.1.19990914132306.00943d30TakeThisOuTspampop.fast.net>, Andy Kunz
<.....supportKILLspamspam@spam@MONTANADESIGN.COM> writes
>>Get in the habit to not reach for *anything* that falls off of a
>>workbench.  Your brain isn't fast enough to evaluate whether it is safe
>
>I have a friend who instinctively caught an Xacto knife that was falling.
>
>Stuck through his palm.  Fortunately it missed the ligaments.

I used to instinctively catch falling soldering irons :-(. I've
eventually managed to train myself out of the habit - hopefully :-).
--

Nigel.

       /--------------------------------------------------------------\
       | Nigel Goodwin   | Internet : nigelgspamKILLspamlpilsley.demon.co.uk     |
       | Lower Pilsley   | Web Page : http://www.lpilsley.demon.co.uk |
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       \--------------------------------------------------------------/

1999\09\15@093039 by Andy Kunz

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>I used to instinctively catch falling soldering irons :-(. I've
>eventually managed to train myself out of the habit - hopefully :-).

Nigel - that ain't too smart!

I was working with an 80W iron the other day solder NiCd cells together
when I slipped.  I grabbed the iron, trying to get it to support me.
That's even stupider than trying to catch one.

Fortunately it did only minor damage, probably due to the fact that I had
ice in my Coke sitting on my bench.

Don't stand up, walk around, and try to solder at the same time - doesn't
work too good!

Andy

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1999\09\16@024058 by Nigel Goodwin

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In message <Pine.SOL.3.91.990915154140.15749A-100000spamspam_OUTtravelers.mail.corn> ell.edu>, Sean Breheny <@spam@shb7KILLspamspamCORNELL.EDU> writes
>Hi Paul,
>
>Thanks for the explanation. When you said that you were surprised that
>the washing machine never tripped it,are you talking about the washer in
>my house? If so, AFAIK, RCDs are NOT standard in US homes. In fact, I
>have never seen such breakers (that I recognized,anyway) on a whole
>circuit,only on individual low-current outlets (usually in bathrooms) and
>integrated into certain appliances (usually hair dryers).
>
>Do homes in OZ usually have one on each circuit?

I don't know about OZ, but in the UK it's common practice to have an RCD
either built in the fusebox, or (as in my house) fitted in the wires
feeding the fusebox. This gives protection for every circuit in the
house, but obviously results in total power failure in the event of a
problem. More modern practice is to have a number of separate RCD's
feeding different circuits, in particular there isn't much need for
having an RCD on any of the lighting circuits!.

Being an occasional viewer of the USA DIY programmes, such as 'This Old
House' and 'Bob Vila's Home Again', I'm horrified by the methods used in
electrical installations in the states!. I can't believe they still use
'Screwit' connections for mains wiring, these were declared illegal in
the UK many, many, years ago!.
--

Nigel.

       /--------------------------------------------------------------\
       | Nigel Goodwin   | Internet : KILLspamnigelgKILLspamspamlpilsley.demon.co.uk     |
       | Lower Pilsley   | Web Page : http://www.lpilsley.demon.co.uk |
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       | England         |                 Ju Jitsu                   |
       \--------------------------------------------------------------/

1999\09\16@095132 by Martin McCormick

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Nigel Goodwin writes:
>House' and 'Bob Vila's Home Again', I'm horrified by the methods used in
>electrical installations in the states!. I can't believe they still use
>'Screwit' connections for mains wiring, these were declared illegal in
>the UK many, many, years ago!.

       Are you referring to the cone-shaped devices that screw down
on two or more wires and hold them together for a while until the hot
lead decides to work out and hit something nearby?

       What is the practice in the UK?

       I have used many of those twist-on connectors and it isn't
always easy to know for sure if they have tightened for good.

       When I was a technician with our Audio Visual Department, I
had one of those things come loose while I was putting a tape deck
back in to its well in a foreign language lab.  Just as I set it in,
the wire nut on the hot AC power lead to the motor fell off and the
bare junction first hit the palm of my hand and then fell across the
audio board of the deck next to this one causing 120 volts to be
injected randomly in to the amplifier.  I felt like the oracle at
Delphi surrounded by magic smoke.  There was a young lady from
Thailand there who was the lab monitor and she thought it was funny.
For months afterward, when I would show up to do work, she would ask
"Are we going to have fireworks today?"  Fortunately, we never did any
more, but I used to check those connections very carefully after all
that.


Martin McCormick WB5AGZ  Stillwater, OK
OSU Center for Computing and Information Services Data Communications Group

1999\09\16@210809 by Mark Willis

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Martin McCormick wrote:
>
> Nigel Goodwin writes:
> >House' and 'Bob Vila's Home Again', I'm horrified by the methods used in
> >electrical installations in the states!. I can't believe they still use
> >'Screwit' connections for mains wiring, these were declared illegal in
> >the UK many, many, years ago!.
>
>         Are you referring to the cone-shaped devices that screw down
> on two or more wires and hold them together for a while until the hot
> lead decides to work out and hit something nearby?
>
>         What is the practice in the UK?
>
>         I have used many of those twist-on connectors and it isn't
> always easy to know for sure if they have tightened for good.
>
> <snipped "Fireworks" story>
> Martin McCormick WB5AGZ  Stillwater, OK
> OSU Center for Computing and Information Services Data Communications Group

"No sense of adventure!"  <EG>

Guys, ya know, it you use electrical tape to immobilize these "Wire
Nuts", these sorts of things don't happen.  At least 2 good wraps on the
nut, 2-3 on the twisted wires coming into them, no unscrewing then.
Sort of like "safety wire" on an aviation bolt or nut.

Of course, I prefer ring terminals crimped & soldered to screw
terminals, but, that's probably against code if used for 117VAC or
220VAC wiring.

 Mark

1999\09\16@210819 by Nigel Goodwin

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In message <PICLIST%RemoveME1999091609513336TakeThisOuTspamMITVMA.MIT.EDU>, Martin McCormick
<spamBeGonemartinspamBeGonespamDC.CIS.OKSTATE.EDU> writes
>Nigel Goodwin writes:
>>House' and 'Bob Vila's Home Again', I'm horrified by the methods used in
>>electrical installations in the states!. I can't believe they still use
>>'Screwit' connections for mains wiring, these were declared illegal in
>>the UK many, many, years ago!.
>
>        Are you referring to the cone-shaped devices that screw down
>on two or more wires and hold them together for a while until the hot
>lead decides to work out and hit something nearby?

Yes, they're the ones :-).

>        What is the practice in the UK?

The cheapest/nastiest items sometimes use 'barrier strip' connectors, I
believe in the USA you call them 'chocolate block' connectors?. Simply a
piece of brass with a hole drilled through the centre, and two other
holes drilled at right angles near the ends and tapped for screws. The
whole lot is then encased in plastic (or porcelain - for heat proof
ones) - usually supplied in long strips and cut to size. Just insert the
wires from either end, and tighten the screws, I'm sure you know what I
mean - even if I've not got the terminology correct.

The 'better quality' items usually have the terminals moulded as part of
the fitting, so for a ceiling rose for a light you would have a part
which fastens to the ceiling and has the terminals moulded in Bakelite
(or some modern similar looking plastic!), there are usually a couple of
extra ones so you can easily wire a switch for the light directly into
the rose. The cover then screws directly over the part mounted on the
ceiling.

>        I have used many of those twist-on connectors and it isn't
>always easy to know for sure if they have tightened for good.

Yes, they seem totally unsafe, I've been a TV service engineer for 28
years, and only ever seen 2 or 3 of those connectors - it was certainly
well before I started work in 1971 that they were banned from use on
mains equipment in the UK. Obviously it's more dangerous in the UK with
240v mains, but I wouldn't trust them at 110v either!.

{Quote hidden}

A bit of smoke always livens the day :-). Isn't life funny, you could
save a whole room full of people from a disaster, win a Nobel prize,
become president! - and you will still be remembered as the guy who
filled the room with smoke :-).
--

Nigel.

       /--------------------------------------------------------------\
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       | Lower Pilsley   | Web Page : http://www.lpilsley.demon.co.uk |
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       \--------------------------------------------------------------/

1999\09\16@230734 by Sean H. Breheny

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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.

Sean

At 12:46 PM 9/16/99 -0700, you wrote:
>Of course, I prefer ring terminals crimped & soldered to screw
>terminals, but, that's probably against code if used for 117VAC or
>220VAC wiring.
>
>  Mark
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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1999\09\17@083324 by M. Adam Davis

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Not every handyman carries a micro-torch (flame, not flashlight!) and a
roll of solder with them.

-Adam

"Sean H. Breheny" wrote:
{Quote hidden}

1999\09\17@132247 by eplus1

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Solder is a bad, bad idea for high current wiring.
dissimilar metal
1) corrosion leads to
2) resistive contacts which results in
3) heating which causes the solder to
4) melt, releasing the wires and possibly starting a fire.

Very strong mechanical contact as in screw terminals or twist caps directly
to the wire is best.

The arguments for twist caps and against screw terminals are
1) again dissimilar metal corrosion which the twist caps avoid.
2) reduced contact with the circuit during installation / modification
3) better insulation (if the wire terminals are left un-covered)
4) much, much lower cost of screw caps (not that that is more important than
safety, right Mr. House Builder?)

James Newton, webmaster http://get.to/techref
(hint: you can add your own private info to the techref)
EraseMEjamesnewtonspamgeocities.com
1-619-652-0593 phone



{Original Message removed}

1999\09\17@133322 by Mark Skeels

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About 12 years ago, when living in Elgin, IL, one of the main conductors in
my home service broke, and I had to rewire the entire house, due to local
code.

You might be interested to know that Elgin reqires soldered connections in
all junction boxes...

Mark

{Original Message removed}

1999\09\17@142002 by Sean H. Breheny

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Hi James,

Thanks for the answer,but as usual,I have a few more questions <G>:

At 08:02 AM 9/17/99 -0700, you wrote:
>Solder is a bad, bad idea for high current wiring.
>dissimilar metal
>1) corrosion leads to
>2) resistive contacts which results in
>3) heating which causes the solder to
>4) melt, releasing the wires and possibly starting a fire.

Hmmmm. It seems to me that in a good solder connection,only the solder
itself is exposed to the outside world. The wire-solder interface should be
completely isolated from the air,hence preventing corrosion.

Also,if what you say is the case,then why is solder used for high current
wiring in some applications (12v power supply cords,etc.)?

>
>Very strong mechanical contact as in screw terminals or twist caps directly
>to the wire is best.

It seems to me that this would actually be MORE prone to corrosion because
the connection between the wires is less likely to be gas-tight. Hence,
corrosion can occur on the mating surface of the wires.

>
>The arguments for twist caps and against screw terminals are
>1) again dissimilar metal corrosion which the twist caps avoid.

But, isn't the metal inside the twist cap something other than copper? If
so,how do they avoid dissimilar metals?

>2) reduced contact with the circuit during installation / modification

Yes, I can see that. However, how often do you really need to make a change
in house wiring?

>3) better insulation (if the wire terminals are left un-covered)

Yes, I see this.

>4) much, much lower cost of screw caps (not that that is more important than
>safety, right Mr. House Builder?)

Yeah,I'd say that IS a factor!

Thanks,

Sean

>
>James Newton, webmaster http://get.to/techref
>(hint: you can add your own private info to the techref)
>RemoveMEjamesnewtonEraseMEspamEraseMEgeocities.com
>1-619-652-0593 phone
>
>
>
>{Original Message removed}

1999\09\17@143909 by Sean H. Breheny

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Hi Mark,

The connection that broke, was it a soldered one?

Sean

At 08:25 AM 9/17/99 -0500, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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1999\09\17@171150 by M. Adam Davis

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As far as the dissimilar metals issue, both screw connectors simply
apply mechanical force to the wires, pushing the wires against each
other.  While there may be some small amount of current flowing through
the twist-on and other connectors, it doesn't matter if it corrodes at
the surface, that would simply increase the resistance, causing less
current to flow through the twist on, which would reduce the rate of
corrosion.

-Adam

"Sean H. Breheny" wrote:
{Quote hidden}

1999\09\17@171204 by eplus1

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<BLOCKQUOTE AUTHOR="Sean H. Breheny"> The wire-solder interface should be
completely isolated from the air, hence preventing corrosion.</BLOCKQUOTE>

Yes it SHOULD be. I saw a lot of this type of corrosion in my 7 years in US
Naval Aviation. Some of it was structural and it corroded from the inside
out! When the corrosion started to become visible on the exterior of the
metal, the inside was found to be completely shot. I can't remember for
sure, but I think that dissimilar metal corrosion maybe don't need air. Or
was it that some oxidizers are trapped during the forming process? Help?

<BLOCKQUOTE AUTHOR="Sean H. Breheny">Also, if what you say is the case, then
why is solder used for high current wiring in some applications (12v power
supply cords, etc.)?</BLOCKQUOTE>

It works just fine for a while....

<BLOCKQUOTE AUTHOR="Sean H. Breheny">It seems to me that this would actually
be MORE prone to corrosion</BLOCKQUOTE>

I personally have seen a number of wire screw terminal (on 5V and 12V
applications) that rusted right through at the contact point. I don't think
these can possibly be very long lived. I would guess that regulatory laws
re: their use may be more related to relatives of legislators who make them
than valid safety arguments. They ARE the best for ensuring a good, strong,
won't-work-free connection, for a while; but house wiring should last for a
long time...

<BLOCKQUOTE AUTHOR="Sean H. Breheny">But, isn't the metal inside the twist
cap something other than copper? If so,how do they avoid dissimilar
metals?</BLOCKQUOTE>

1. The cap insert to wire contact may corrode, but the connection between
the wires (as they are pressed together) does not.
2. Twisting the cap sufficiently (as per usage direction) also twists the
wires together so if all else fails, you still have a (poor) mechanical
connection between the wires, and the plastic part of the cap insulating it.
3. Since the wires are twisted together, if they get hot enough, they will
weld to other together (I've seen this) and the plastic cap will melt at a
much lower temp than the solder so its not much of a fire hazard. You still
get a nice fire if the junction is setting near a flammable object though!
That why hi temp junction boxes and "goof rings" around the hole in the
paneling are required now.
3. Recently all the screw caps I have seen have been completely plastic,
including the interior threads. IMHO this type of screw cap, combined with
electrical tape (as Mark suggested) or a blob of SRS in the bottom of the
cap around the wires is the overall best solution.

James Newton, webmaster http://get.to/techref
(hint: you can add your own private info to the techref)
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1999\09\18@014157 by Russell McMahon

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Important note -

A trap for young and not so young players.

If you are terminating wires using screw down terminals (chocolate blocks,
terminal blocks, rising clamp connectors, ....) you should NOT solder the
whole end.

A soldered wire will deform en masse from round to flat and retain its new
shape. If there is vibration and tension on the wire and/or block, in time
the wire can deform to a size less than the mean gap under the screw or
clamp and work loose. A bundle of separate copper wires does not do this (or
at least, does it much less.).

Some regulations, which prohibit soldering for this reason, do allow you to
solder the tip only of the wire to keep the strands together.



regards

                   Russell McMahon

_______________________________________
What can one man do?  Help the hungry for free at
http://www.thehungersite.com/


From: M. Adam Davis <EraseMEadavisspamspamspamBeGoneUBASICS.COM>


>Not every handyman carries a micro-torch (flame, not flashlight!) and a
>roll of solder with them.
>
>-Adam
>
>"Sean H. Breheny" wrote:
>>
>> 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
{Quote hidden}

1999\09\20@095042 by Andy Kunz

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At 08:31 AM 9/17/99 -0400, you wrote:
>Not every handyman carries a micro-torch (flame, not flashlight!) and a
>roll of solder with them.

If they did, we'd have a lot more calls to the local fire dept!

Andy

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1999\09\24@122824 by Martin McCormick

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Russell McMahon writes:
>If you are terminating wires using screw down terminals (chocolate blocks,
>terminal blocks, rising clamp connectors, ....) you should NOT solder the
>whole end.

       An excellent point.  Again, when I was fixing tape recorders
and film projectors for our Audio Visual department, we often replaced
the AC or mains plugs on equipment when the cord was damaged or
somebody had cut off the Earth prong or, in some cases, pulled it out
with pliers, fearing it might grow back.:-)  We started tinning the
new wire in the cord before tightening the screws down.  It looked so
neat.  A few months after doing this, equipment we had fixed started
coming back in with loose connections on those plugs.  It was
instantly obvious what kind of monster we had created so we quit doing
that immediately.  Sometimes, the road to Hell is paved with good
intentions.  I hate to say it, but I may have even been the one to
suggest tinning and everybody else thought that sounded good.
Everybody there was technically competent and it was just one of those
good ideas that wasn't appropriate for the situation.

       On the topic of dissimilar metals which has also appeared in
this thread, I remember the big scare over aluminum house wiring which
occurred in the United States during the seventies or so.  Lots of
houses were wired with this stuff and they began to burn down after
people incorrectly installed fixtures rated for copper wiring on the
aluminum cables.  The gauge of the wire was slightly larger to begin
with and so it didn't fit well under the screw.  A little thermal
cycling and electrolysis of the aluminum/brass junction would create a
resistance heater which would one day get red hot and start a fire if
someone connected anything substantial to that outlet.

       I think aluminum is still used in the service drop from the
pole to the meter, but those connections are especially designed for
the purpose and I don't believe there is any particular problem with
them.

       Another thing about dissimilar metals.  We used to live in a
house that was built in 1951.  Some time in the mid sixties, the
previous owner replaced the galvanized steel pipe with copper
plumbing.  Somebody didn't know what they were doing for they attached
the new copper line to the house to a steel fitting on the meter
without an insulating fitting.  One evening, we came home to find a
note from the city on our door saying that they had turned off our
water during the day because a flood had burst forth from the meter
and was flowing in to the street and freezing.  All because of
galvanic action over 20 years between the copper and the steel of the
fitting.

       The same bright soul who did that also used a steel reducer in
the kitchen on each copper line to the sink and I was lucky in that I
discovered those when replacing the faucet, one day.  The hot fitting
was much more corroded than was the cold water line, probably due to
the heat accelerating the electro chemical activity.  It looks like
steel becomes the cathode in one of these little batteries from Hell.

Martin McCormick

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