Hello

Over the Christmas period I replaced all the pendant lights in my house. They
all had shades I didn't like and those shades were screwed in to a lamp
holder which wouldn't take the replacement shades, so I changed the lamp
holders of course. These new lamp holders are pretty standard "British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

--
Patrick

patrick j wrote:
Hello

Over the Christmas period I replaced all the pendant lights in my house. They
all had shades I didn't like and those shades were screwed in to a lamp
holder which wouldn't take the replacement shades, so I changed the lamp
holders of course. These new lamp holders are pretty standard "British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.



The theory goes that the solder will 'flow' over time and the joint will
loosen. Once the joint starts to loosen, there will be an increase in
heat, softening the solder further and a vicious circle ensues.

Personally, I strip slightly more insulation, twist and double back the
conductor.
Andrew

"patrick j" wrote in message
. com...
Hello

Over the Christmas period I replaced all the pendant lights in my
house. They
all had shades I didn't like and those shades were screwed in to a
lamp
holder which wouldn't take the replacement shades, so I changed the
lamp
holders of course. These new lamp holders are pretty standard
"British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've
always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing
and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful
if
someone would explain to me why soldered cable ends are a bad thing.

--
Patrick

At a guess it's because with soldered ends don't 'give' when you tighten
the screw.
1 - you could end up with contact just along the two opposite sides of
the solid cable, rather than letting the cable compress to give a larger
area of contact.

2- Also if the soldered end was roughly elliptical in section the same
lack of 'give' could allow you to tighten the screw onto the wider axis
and it would seem to be firm; but if the cable rotates it could come
loose giving arcing.

So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.
I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Perhaps some sort of reaction between dissimilar metals ? (can`t remember
the phrase)

--
Please add "[newsgroup]" in the subject of any personal replies via email
--- My new email address has "ngspamtrap" & @btinternet.com in it ;-) ---

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing and
of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.



The theory goes that the solder will 'flow' over time and the joint will
loosen. Once the joint starts to loosen, there will be an increase in
heat, softening the solder further and a vicious circle ensues.

Personally, I strip slightly more insulation, twist and double back the
conductor.

this is the explanation I have heard, and I twist and double back too )

"OG" wrote in message ...

"patrick j" wrote in message
. com...
Hello

Over the Christmas period I replaced all the pendant lights in my
house. They
all had shades I didn't like and those shades were screwed in to a
lamp
holder which wouldn't take the replacement shades, so I changed the
lamp
holders of course. These new lamp holders are pretty standard
"British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've
always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing
and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful
if
someone would explain to me why soldered cable ends are a bad thing.

--
Patrick

At a guess it's because with soldered ends don't 'give' when you tighten
the screw.

yup

that's the reason I snip the tinned ends off any electrical appliance supplied
without a plug. I only tin copper wires when I'm soldering, i.e audio cables.



RT

patrick j wrote:

I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

I seem to remember it only being usual to 'tin' stranded cable, not
solid core, also that tightening a tinned cable in a screw-connector
could tend to make the solder dry or crystalline, possibly giving high
resistance (and therefore heating) or even sometimes forming a partial
diode?

"patrick j" wrote in message
. com...
So it looks like MK believe that soldered cable ends are a bad thing and
of course I did not put solder on the cable ends.

On occation I've found the soldered part under the terminal screw can
fracture entirely.

IMO it would be ok to solder just the tip of the loose ends to stop them
splaying out, but making sure the part under the screw terminal was free of
solder. I've seen this or the ends crimped into a brass ferrule on some
manufactured retail products, presumably to speed assembly and ensure no
odd whiskers cause shorts.

Roger

patrick j wrote:

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Because soft solder creeps under the compressive load of the screw,
resulting in a loose connection after a period of a few months or so.

Re-visit some of the ones you did earlier and the chances are that
you'll find that they're all loose.

MK are right; tinning the ends is very bad practice. If you want tidy
wire ends use crimped bootlace ferrules, or crimped ring terminals as
appropriate.

--
Andy

Andy Wade wrote:


MK are right; tinning the ends is very bad practice. If you want tidy
wire ends use crimped bootlace ferrules, or crimped ring terminals as
appropriate.


Dead right. The reason some wires come pre-tinned (and plugless in some
cases, equipment construction regs notwithstanding) is that it makes
final test easier for the manufacturer. Tinning the ends uses kit
already in the factory, at minimal consumables cost too compared to a
bootlace or similar. Popping the non-straggling tinned ends into a
spring-loaded source of 240VAC/110VAC is quick'n'easy (no whiskers of
cable to cause shorts). Cutting off the tinned ends is an extra process
which the volume contract manufacturers won't undertake unless
explicitly told (and paid) to do so...

Stefek

On Tue, 4 Jan 2005 22:15:09 +0000, patrick j wrote:

Hello

Over the Christmas period I replaced all the pendant lights in my house. They
all had shades I didn't like and those shades were screwed in to a lamp
holder which wouldn't take the replacement shades, so I changed the lamp
holders of course. These new lamp holders are pretty standard "British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Solder is very soft, and has no springiness to maintain contact pressure over changes in things like
temperature. This will be a particular issue for lampholders, which undergo significant temperature
cycling.

What do you mean by pretty standard British?


Andrew Chesters wrote:
patrick j wrote:
Hello

Over the Christmas period I replaced all the pendant lights in my
house. They
all had shades I didn't like and those shades were screwed in to a
lamp
holder which wouldn't take the replacement shades, so I changed the
lamp
holders of course. These new lamp holders are pretty standard
"British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting
I've always
put some solder on the exposed cable which I'm going to screw into
the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad
thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be
grateful if
someone would explain to me why soldered cable ends are a bad
thing.



The theory goes that the solder will 'flow' over time and the joint
will
loosen. Once the joint starts to loosen, there will be an increase
in
heat, softening the solder further and a vicious circle ensues.

Personally, I strip slightly more insulation, twist and double back
the
conductor.
Andrew

wrote:
What do you mean by pretty standard British?

SNIP

I don't mean anything by it! The OP probably means a standard plastic
BC pendant holder. Why?

Andrew

In message , patrick j
writes
So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Yes MK are correct. As others say, the solder is soft and creeps over
time leaving a loose joint.
If you've been in the habit of soldering your wires, then I suggest you
go round every item in your house and redo the plugs etc without
applying solder. I suspect you'll find several loose ones if you do
this!

--
steve

On Wed, 5 Jan 2005 17:56:03 +0000, Steven Briggs wrote
(in message ):

In message , patrick j
writes
So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Yes MK are correct. As others say, the solder is soft and creeps over
time leaving a loose joint.
If you've been in the habit of soldering your wires, then I suggest you
go round every item in your house and redo the plugs etc without
applying solder. I suspect you'll find several loose ones if you do
this!

Thank you and for all the other replies to my query. Fortunately I have done
hardly any plugs or any electrical work in the house I now own so it is good
that I now know putting solder on cable ends is a bad idea

From here on in I will strip slightly more insulation, twist and double back
the conductor.

--
Patrick

In message , patrick j
writes
So it looks like MK believe that soldered cable ends are a bad thing and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

One reason I remember reading was that it's because the solder 'flows'
under pressure and you end up with a loose connection.
Soldering a flex connection is always a bad idea where there may be
movement anyway because the solder can contribute to a stress fracture
in the cable, it's quite common to see cables fail on cars where a
'technician' has soldered a Lucar connector on.
--
Clint Sharp

In article ,
Clint Sharp wrote:
it's quite common to see cables fail on cars where a 'technician' has
soldered a Lucar connector on.

It's also common on old cars to get a high resistance crimped Lucar
connector.

--
*To be intoxicated is to feel sophisticated, but not be able to say it.

Dave Plowman London SW
To e-mail, change noise into sound.

In article .com,
wrote:

What do you mean by pretty standard British?

http://www.allmyfaqs.com/faq.pl?How_to_post

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

patrick j wrote:


From here on in I will strip slightly more insulation, twist and double back
the conductor.


Aye, that's the business. Unless you're wiring a nice MK plug, or
similar post connector (rather than a feed-through hole). In that case,
you strip a surprising length of insulation off the core (pi being as
big as it is ;-), form a nice loop around your small screwdriver, turn
the end under the part closer to the insulation (clockwise, of course,
to emulate the thread on the post), and ease it down onto the plug post.
Tighten the slotted-knurled-nut-with-captive-washer firmly onto same.
Now you've got a nice broad contact area for your electrickle
connection; once you have the habit you won't be able to shake even if
you're wiring a 15W lava-lamp rather'n kettle, 3kW fan heater, or other
high-load appliance where it could possibly matter ;-)

Stefek