Rigger's Diary

On Tue, 11 Aug 2009 19:19:16 +0100, "Bill Wright"
wrote:


"charles" wrote in message
. ..
In article ,
I suspect it's generally plug in wiring rather than installed that is the
cause of most problems. However I did once save a friend's few hundred
year old barn when I went to use a (professionally installed) socket to
plug in a PA sysytem. The other half of the socket was feeding a 3kW
electric fire and the socket was almost too hot to touch. Either the
cable
securing screws hadn't been done up tight or the plug was a very poor fit
in the socket - but whichever, the barn would probably caught fire that
night idf I hadn't spotted the problem

I think these terminal screws come loose. I recently removed 11 double 13A
outlets from a kitchen that was being refurbished (in preparation for the
electricians) and virtually every screw was loose, some very much so.

Bill


BT found that the 16mm2 cable that was terminated into a fuse holder
(136A ISTR but if not someone will be along to correct me) became
loose after a relatively short period of time.

The investigation they carried out came up with the reaon for this as
"Copper Relaxation" (the conductor was stranded) and the solution was
to crimp a solid piece of copper onto the cable and terminate that
under the screw of the fuseholder - worked well
--
Cheers

Peter

On Wed, 12 Aug 2009 09:26:13 +0100, Petert
wrote:

On Tue, 11 Aug 2009 19:19:16 +0100, "Bill Wright"
wrote:


"charles" wrote in message
.. .
In article ,
I suspect it's generally plug in wiring rather than installed that is the
cause of most problems. However I did once save a friend's few hundred
year old barn when I went to use a (professionally installed) socket to
plug in a PA sysytem. The other half of the socket was feeding a 3kW
electric fire and the socket was almost too hot to touch. Either the
cable
securing screws hadn't been done up tight or the plug was a very poor fit
in the socket - but whichever, the barn would probably caught fire that
night idf I hadn't spotted the problem

I think these terminal screws come loose. I recently removed 11 double 13A
outlets from a kitchen that was being refurbished (in preparation for the
electricians) and virtually every screw was loose, some very much so.

Bill


BT found that the 16mm2 cable that was terminated into a fuse holder
(136A ISTR but if not someone will be along to correct me) became
loose after a relatively short period of time.

The investigation they carried out came up with the reaon for this as
"Copper Relaxation" (the conductor was stranded) and the solution was
to crimp a solid piece of copper onto the cable and terminate that
under the screw of the fuseholder - worked well

I saw that effect with stranded cable. I would sometimes solder the
strands together for a centimetre or so. This was in non-demanding
situations particularly where the strands were fine.

--
Peter Duncanson
(in uk.tech.digital-tv)

In article ,
Peter Duncanson wrote:
I saw that effect with stranded cable. I would sometimes solder the
strands together for a centimetre or so. This was in non-demanding
situations particularly where the strands were fine.

IIRC, soldering stranded cable at a clamp terminal is frowned on. Not sure
of the theory. The correct way is to crimp on a terminal then clamp to
that.

--
*The early bird gets the worm, but the second mouse gets the cheese *

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

Dave Plowman (News) wrote:
In article ,
Peter Duncanson wrote:
I saw that effect with stranded cable. I would sometimes solder the
strands together for a centimetre or so. This was in non-demanding
situations particularly where the strands were fine.

IIRC, soldering stranded cable at a clamp terminal is frowned on. Not sure
of the theory. The correct way is to crimp on a terminal then clamp to
that.

Its because the solder can "creep" under pressure from the terminal
screw and leave a loose joint. As you say, bootlace ferrules crimped on
are probably the best solution.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Wed, 12 Aug 2009 13:51:07 +0100, "Dave Plowman (News)"
wrote:

In article ,
Peter Duncanson wrote:
I saw that effect with stranded cable. I would sometimes solder the
strands together for a centimetre or so. This was in non-demanding
situations particularly where the strands were fine.

IIRC, soldering stranded cable at a clamp terminal is frowned on. Not sure
of the theory. The correct way is to crimp on a terminal then clamp to
that.

Yes, but I did refer to "non-demanding situations" - low voltage, low
current, etc.

--
Peter Duncanson
(in uk.tech.digital-tv)

On Wed, 12 Aug 2009 17:32:55 +0100, Peter Duncanson
wrote:

On Wed, 12 Aug 2009 13:51:07 +0100, "Dave Plowman (News)"
wrote:

In article ,
Peter Duncanson wrote:
I saw that effect with stranded cable. I would sometimes solder the
strands together for a centimetre or so. This was in non-demanding
situations particularly where the strands were fine.

IIRC, soldering stranded cable at a clamp terminal is frowned on. Not sure
of the theory. The correct way is to crimp on a terminal then clamp to
that.

Yes, but I did refer to "non-demanding situations" - low voltage, low
current, etc.

I should add that I only ever did this to my own stuff, never in a
professional context.

--
Peter Duncanson
(in uk.tech.digital-tv)

In article , Dave Plowman (News) wrote:
IIRC, soldering stranded cable at a clamp terminal is frowned on. Not sure
of the theory. The correct way is to crimp on a terminal then clamp to
that.

I used to solder stranded cable ends for neatness, but they always worked
loose from screw terminals after a few years. Since I stopped doing it and
started simply twisting the bare copper strands together before putting them
into the terminals, I've had no further trouble of this sort.

Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/

On Wed, 12 Aug 2009 19:38:04 +0100, Roderick Stewart wrote:

I used to solder stranded cable ends for neatness, but they always
worked loose from screw terminals after a few years.

If the bare stranded end was curled on to itself to form a loop of
just the right diameter, and then soldered so that the loop fitted
over the pin screw and then the cover screwed on, would not the problem
of the soldered strip coming away from the under the screw terminal
be avoided?

In article , J G Miller wrote:
I used to solder stranded cable ends for neatness, but they always
worked loose from screw terminals after a few years.

If the bare stranded end was curled on to itself to form a loop of
just the right diameter, and then soldered so that the loop fitted
over the pin screw and then the cover screwed on, would not the problem
of the soldered strip coming away from the under the screw terminal
be avoided?

I did things like that too, and they always worked loose. A few times I
noticed crunchy noises from my loudspeakers when walking across the room
and eventually traced them to loose mains connections in plugs or
distribution boards. I wondered why it was happening because I'd been
meticulous about making up any mains connections very carefully, but
eventually noticed it was my neatly soldered wire ends that were working
loose from any kind of screw grip, and the untidy ones that other people
had made up with just the bunched up wire stayed tight. It happens quite
slowly, over a number of years, but it seems consistent. Whenever I
needed to rewire something that had been done with solder, I'd have no
difficulty undoing the grub screws, and they'd sometimes be so loose I
wondered how they made a connection at all.

I don't know what causes this but I think most likely it's a combination
of temperature cycling and the juxtaposition of a relatively hard metal
(brass) and a very soft one (solder). At any rate it doesn't happen if I
don't use solder to neaten the ends of a gripped wire.

Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/

On Wed, 12 Aug 2009 23:10:28 +0100, Roderick Stewart
wrote:

In article , J G Miller wrote:
I used to solder stranded cable ends for neatness, but they always
worked loose from screw terminals after a few years.

If the bare stranded end was curled on to itself to form a loop of
just the right diameter, and then soldered so that the loop fitted
over the pin screw and then the cover screwed on, would not the problem
of the soldered strip coming away from the under the screw terminal
be avoided?

I did things like that too, and they always worked loose. A few times I
noticed crunchy noises from my loudspeakers when walking across the room
and eventually traced them to loose mains connections in plugs or
distribution boards. I wondered why it was happening because I'd been
meticulous about making up any mains connections very carefully, but
eventually noticed it was my neatly soldered wire ends that were working
loose from any kind of screw grip, and the untidy ones that other people
had made up with just the bunched up wire stayed tight. It happens quite
slowly, over a number of years, but it seems consistent. Whenever I
needed to rewire something that had been done with solder, I'd have no
difficulty undoing the grub screws, and they'd sometimes be so loose I
wondered how they made a connection at all.

I don't know what causes this but I think most likely it's a combination
of temperature cycling and the juxtaposition of a relatively hard metal
(brass) and a very soft one (solder). At any rate it doesn't happen if I
don't use solder to neaten the ends of a gripped wire.

I can't offer an explanation for this but I found that the connection
lasted longest if I didn't tighten the screw as far as it would possibly
go - tight but not tightest.

--
Peter Duncanson
(in uk.tech.digital-tv)