Piece of T&E behind a hardboard facing on a damp wall of an old
stone-built ex-barn, socket slightly damp too. Lots of green stuff all
over the Copper. Obviously the screw terminations are a bit iffy so the
faceplate gets replaced, but what about the cable? Insulation tests L-N
are fine, N-E is ok, L-E is slightly lower than expected.

The green stuff is only on the bare ends of the L & N wires - i.e. only
as far as the insulation, but tracks about 2ft up the bare earth (I took
out a 4ft section to see).

So for the chemists here (I'm sure there must be some) what is happening
to the Copper? What is the green stuff? How does green stuff manage to
reduce the insulation test readings? On a similar bit of cable without
the reduction in insulation resistance readings would sandpapering the
green stuff off and re-terminating be ok?

This green stuff seems very similar to the usual sort of thing which
happens to Copper if left outside / in the damp, but its electrical
properties don't really matter on water pipes or roof ornaments :-)

Oh, and as to the original cause, stopping the damp is going to be
mighty difficult - the wall in question is stone/rubble-built,
questionable mortar, and underground :-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... I'm not nearly as think as you confused I am.

What is the green stuff? How does green stuff manage to
reduce the insulation test readings? On a similar bit of cable without
the reduction in insulation resistance readings would sandpapering the
green stuff off and re-terminating be ok?

All metals when exposed to the atmosphere react and start to corode. Alliminium
reacts almost instantly and over time a white dust appears and this is
alliminum hydroxide. copper reacts the same but turns green, cant remember
wether the green stuff is copper oxide ot hydroxide. the insulation test you
did , did you put put 500V through the conductors ? On a digital ohm meter you
should expect a reading of greater than 999 Mohms or infinity on an analougue
meter. yes , emery cloth and clean and re terminate. I work on the 400KV grid
OHLines and when we get hot joints ( high resistance , which is what your green
terminations are ) we break the joints , file them shiny clean apply a thin
layer of grease and re make the joints then mega them again.

In article ,
Wheelbarrowbob writes
What is the green stuff? How does green stuff manage to
reduce the insulation test readings? On a similar bit of cable without
the reduction in insulation resistance readings would sandpapering the
green stuff off and re-terminating be ok?

All metals when exposed to the atmosphere react and start to corode. Alliminium
reacts almost instantly and over time a white dust appears and this is
alliminum hydroxide. copper reacts the same but turns green, cant remember
wether the green stuff is copper oxide ot hydroxide. the insulation test you
did , did you put put 500V through the conductors ? On a digital ohm meter you
should expect a reading of greater than 999 Mohms or infinity on an analougue
meter. yes , emery cloth and clean and re terminate. I work on the 400KV grid
OHLines and when we get hot joints ( high resistance , which is what your green
terminations are ) we break the joints , file them shiny clean apply a thin
layer of grease and re make the joints then mega them again.

That somehow sounds amusing "we megger them"

Any piccys of your day job on a website Bob?...
--
Tony Sayer

snip file them shiny clean apply a thin layer of grease and re make the
joints then mega them again.
That somehow sounds amusing "we megger them"
Any piccys of your day job on a website Bob?...

I`m more interested in the kit they use to megger them...

Would I be right in thinking you use a ducter rather than a megger to
check the resistance of the joint, as you would on breakers ?

(I used to work on ground mounted 11kv & 33kv plant)

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

On Fri, 30 Apr 2004 00:52:22 +0100, Colin Wilson
wrote:

Would I be right in thinking you use a ducter rather than a megger to
check the resistance of the joint, as you would on breakers ?

Sounds interesting. I've heard of a megger but not a ducter. What is a
ducter please?

PoP

---
http://www.ukdiy.org.uk

A ducter is a digital ohm meter made by megger and is 10 inches by 5 inches and
10 inches deep with 4 test leads about 30ft long all incased in a big orange
plastic box with a carry strap so a donkey like me can carry it 200 ft up a
tower and measure the resistance of the joints on an earth wire ( single wire
at top of transmission tower )

Martin Angove wrote:

Piece of T&E behind a hardboard facing on a damp wall of an old
stone-built ex-barn, socket slightly damp too. Lots of green stuff all
over the Copper. Obviously the screw terminations are a bit iffy so the
faceplate gets replaced, but what about the cable? Insulation tests L-N
are fine, N-E is ok, L-E is slightly lower than expected.

The green stuff is only on the bare ends of the L & N wires - i.e. only
as far as the insulation, but tracks about 2ft up the bare earth (I took
out a 4ft section to see).

So for the chemists here (I'm sure there must be some) what is happening
to the Copper? What is the green stuff? How does green stuff manage to
reduce the insulation test readings? On a similar bit of cable without
the reduction in insulation resistance readings would sandpapering the
green stuff off and re-terminating be ok?

This green stuff seems very similar to the usual sort of thing which
happens to Copper if left outside / in the damp, but its electrical
properties don't really matter on water pipes or roof ornaments :-)

Oh, and as to the original cause, stopping the damp is going to be
mighty difficult - the wall in question is stone/rubble-built,
questionable mortar, and underground :-)



Its copper carbonate. Its sort of potects the copper from further
corrision. If there is any sign of blackening tho, you may be in
trouble. Do a google on Black Wire Syndrome. That doesn't stop until the
wire breaks, and then loss of connectivity is far preferable to a nice
arc and a fire..


Hwyl!

M.

Wheelbarrowbob wrote:

What is the green stuff? How does green stuff manage to
reduce the insulation test readings? On a similar bit of cable without
the reduction in insulation resistance readings would sandpapering the
green stuff off and re-terminating be ok?


All metals when exposed to the atmosphere react and start to corode.


Except noble metals like gold and platinum.

Alliminium
reacts almost instantly


To form a highly impervious oxide layer.

and over time a white dust appears and this is
alliminum hydroxide.


But this generally takes a weak acid to form.

copper reacts the same but turns green, cant remember
wether the green stuff is copper oxide ot hydroxide.


Neither. Copper oxide is black. Its usally copper carbonate from the
carbonic acid in rainwater. Most houses are full of carbpon dioxide as
well ...tends to be a by product of any rainwater and cements.

I can't remember, but ISTR copper hydroxide is more pale bluish. Not as
blue as the sulphate...

Martin Angove wrote in message ...

Oh, and as to the original cause, stopping the damp is going to be
mighty difficult - the wall in question is stone/rubble-built,
questionable mortar, and underground :-)


If cable insulation value is reduced by water presence I wouldnt be
comfortable reusing it. At what voltage did you test this R? Thats an
important question.

PVC cable is impervious to water so to prevent rewetting all one need
do is keep the cut end dry. Mounting your electrics on standoffs helps
greatly to keep the damp from a damp wall away from the lectrickery.
Also vent holes in the underside of the boxes - must be kids finger
proof - can help.


Regards, NT

On 30 Apr 2004 11:31:38 GMT, (Wheelbarrowbob)
wrote:

A ducter is a digital ohm meter made by megger and is 10 inches by 5 inches and
10 inches deep with 4 test leads about 30ft long all incased in a big orange
plastic box with a carry strap so a donkey like me can carry it 200 ft up a
tower and measure the resistance of the joints on an earth wire ( single wire
at top of transmission tower )

Wow. I realised that those things were pretty big, but had not
realised that they were that high.

Eaves level on the house is my limit and I'm not comfortable then.

I hope that you're well rewarded for this work.....



..andy

To email, substitute .nospam with .gl

On Fri, 30 Apr 2004 13:20:06 +0100, Andy Hall
wrote:

Eaves level on the house is my limit and I'm not comfortable then.

I won't even do that.

Interesting story time.....

About 8 years ago I worked for Lanier in Wokingham, and our office was
on the top floor. This was the 2nd floor, and the floors were quite
high.

We were sitting in the office one summer day and this ladder appears
at the window - just over the sill, not all the way up. And the ladder
started shaking as it does when someone is climbing up it. This ladder
must've been extended to about 40 feet, and when we looked out this
ladder must have been whipping back and forth a good couple of feet in
the central section as the guy climbed up/down.

A few seconds later this guy reaches the top rung - and carries on
climbing! I'm not kidding when I say he stood on the last rung but one
to reach up and clean the windows - his knees were at the top of the
ladder. He was just balanced very precariously at the top of this
shaky wooden ladder.

Unbelievable that someone could do that without falling off.

PoP

---
http://www.ukdiy.org.uk

In article ,
says...
On Fri, 30 Apr 2004 13:20:06 +0100, Andy Hall
wrote:

Eaves level on the house is my limit and I'm not comfortable then.

I won't even do that.

Interesting story time.....

About 8 years ago I worked for Lanier in Wokingham, and our office was
on the top floor. This was the 2nd floor, and the floors were quite
high.

We were sitting in the office one summer day and this ladder appears
at the window - just over the sill, not all the way up. And the ladder
started shaking as it does when someone is climbing up it. This ladder
must've been extended to about 40 feet, and when we looked out this
ladder must have been whipping back and forth a good couple of feet in
the central section as the guy climbed up/down.

A few seconds later this guy reaches the top rung - and carries on
climbing! I'm not kidding when I say he stood on the last rung but one
to reach up and clean the windows - his knees were at the top of the
ladder. He was just balanced very precariously at the top of this
shaky wooden ladder.

Unbelievable that someone could do that without falling off.


I have no problem with going to any height on a ladder, and working from
it, but get vertigo if I go on a tower, or flat roof. Pitched roofs, even
on a bungalow with eaves 7' from the ground, and I'm petrified. My shed
roof is about 6' up, flat, and 20' x 10'. If I have to go up there to
fiddle with the aerials, I can't look down.

Is this a weird combination, or is anybody else the same?

Gary

In article , Gary Cavie
writes
In article ,
says...
On Fri, 30 Apr 2004 13:20:06 +0100, Andy Hall
wrote:

Eaves level on the house is my limit and I'm not comfortable then.

I won't even do that.

Interesting story time.....

About 8 years ago I worked for Lanier in Wokingham, and our office was
on the top floor. This was the 2nd floor, and the floors were quite
high.

We were sitting in the office one summer day and this ladder appears
at the window - just over the sill, not all the way up. And the ladder
started shaking as it does when someone is climbing up it. This ladder
must've been extended to about 40 feet, and when we looked out this
ladder must have been whipping back and forth a good couple of feet in
the central section as the guy climbed up/down.

A few seconds later this guy reaches the top rung - and carries on
climbing! I'm not kidding when I say he stood on the last rung but one
to reach up and clean the windows - his knees were at the top of the
ladder. He was just balanced very precariously at the top of this
shaky wooden ladder.

Unbelievable that someone could do that without falling off.


I have no problem with going to any height on a ladder, and working from
it, but get vertigo if I go on a tower, or flat roof. Pitched roofs, even
on a bungalow with eaves 7' from the ground, and I'm petrified. My shed
roof is about 6' up, flat, and 20' x 10'. If I have to go up there to
fiddle with the aerials, I can't look down.

Is this a weird combination, or is anybody else the same?

Gary

Well I've been up a TV transmitting mast on a windy day to 770 feet and
after the first couple of hundred you don't really notice much
difference, except the swaying motion gets worse the higher you go!..
--
Tony Sayer

Gary Cavie wrote:

I have no problem with going to any height on a ladder, and working from
it, but get vertigo if I go on a tower, or flat roof. Pitched roofs, even
on a bungalow with eaves 7' from the ground, and I'm petrified. My shed
roof is about 6' up, flat, and 20' x 10'. If I have to go up there to
fiddle with the aerials, I can't look down.

Is this a weird combination, or is anybody else the same?

Gary


Brother-in-law has had a bad fear of heights since childhood, as have
both his sisters and mother (guess where the children get the fear from?
Thanks Mum). Anyway, they were much amused that he more or less cured
his fear by becoming a roofer. He can now do all those frightening
things roofers do, like walk along ridges. But he cannot go near the
edges of flat roofs.

Rgd sRichard

"Gary Cavie" wrote in message
t...
In article ,
says...
On Fri, 30 Apr 2004 13:20:06 +0100, Andy Hall
wrote:

Eaves level on the house is my limit and I'm not comfortable then.

I won't even do that.

Interesting story time.....

About 8 years ago I worked for Lanier in Wokingham, and our office was
on the top floor. This was the 2nd floor, and the floors were quite
high.

We were sitting in the office one summer day and this ladder appears
at the window - just over the sill, not all the way up. And the ladder
started shaking as it does when someone is climbing up it. This ladder
must've been extended to about 40 feet, and when we looked out this
ladder must have been whipping back and forth a good couple of feet in
the central section as the guy climbed up/down.

A few seconds later this guy reaches the top rung - and carries on
climbing! I'm not kidding when I say he stood on the last rung but one
to reach up and clean the windows - his knees were at the top of the
ladder. He was just balanced very precariously at the top of this
shaky wooden ladder.

Unbelievable that someone could do that without falling off.


I have no problem with going to any height on a ladder, and working from
it, but get vertigo if I go on a tower, or flat roof. Pitched roofs, even
on a bungalow with eaves 7' from the ground, and I'm petrified. My shed
roof is about 6' up, flat, and 20' x 10'. If I have to go up there to
fiddle with the aerials, I can't look down.

Is this a weird combination, or is anybody else the same?

I'm the same.

I suspect it's because on a ladder I don't look down. On a roof I cling to
what's most central. On a cathedral roof I sit in the middle and whimper ...

Mary

Gary

In message ,
(N. Thornton) wrote:

Martin Angove wrote in message ...

Oh, and as to the original cause, stopping the damp is going to be
mighty difficult - the wall in question is stone/rubble-built,
questionable mortar, and underground :-)


If cable insulation value is reduced by water presence I wouldnt be
comfortable reusing it. At what voltage did you test this R? Thats an
important question.

PVC cable is impervious to water so to prevent rewetting all one need
do is keep the cut end dry. Mounting your electrics on standoffs helps
greatly to keep the damp from a damp wall away from the lectrickery.
Also vent holes in the underside of the boxes - must be kids finger
proof - can help.


Good point, having thought about it most of the "insulation breakdown" I
was measuring was probably at the terminations rather than in the length
of cable, but it made sense to replace 4ft anyway as it was relatively
easy. Yes, I did it properly using the right kit and 500V :-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Me, indecisive? I don't think I am, do you?

"Martin Angove" wrote in message
...
Piece of T&E behind a hardboard facing on a damp wall of an old
stone-built ex-barn, socket slightly damp too. Lots of green stuff all
over the Copper. Obviously the screw terminations are a bit iffy so the
faceplate gets replaced, but what about the cable? Insulation tests L-N
are fine, N-E is ok, L-E is slightly lower than expected.

The green stuff is only on the bare ends of the L & N wires - i.e. only
as far as the insulation, but tracks about 2ft up the bare earth (I took
out a 4ft section to see).

So for the chemists here (I'm sure there must be some) what is happening
to the Copper? What is the green stuff?

I've been reading this thread carefully and while I can't comment on the
technical electrical stuff I used to be a chemist so, because I haven't seen
any correct response to this specific question I'll tell you.

It's almost certainly copper carbonate (cupric carbonate-hydoxide), a pale
green powder as opposed to a crystalline salt. Copper in the presence of
atmospheric moisture and carbon dioxide produces copper carbonate. Cupric
oxide is black by the way, cuprous oxide is red.

This green stuff seems very similar to the usual sort of thing which
happens to Copper if left outside / in the damp,

That's because it's the same stuff.

Mary

Martin Angove wrote in message ...

Good point, having thought about it most of the "insulation breakdown" I
was measuring was probably at the terminations rather than in the length
of cable, but it made sense to replace 4ft anyway as it was relatively
easy. Yes, I did it properly using the right kit and 500V :-)

Thats a relief! I was imagining someone measuring breakdown at 3v then
putting it into service. eek!


Regards, NT

In message ,
"Mary Fisher" wrote:


"Martin Angove" wrote in message
...
Piece of T&E behind a hardboard facing on a damp wall of an old
stone-built ex-barn,

[...]

So for the chemists here (I'm sure there must be some) what is happening
to the Copper? What is the green stuff?

I've been reading this thread carefully and while I can't comment on the
technical electrical stuff I used to be a chemist so, because I haven't seen
any correct response to this specific question I'll tell you.

It's almost certainly copper carbonate (cupric carbonate-hydoxide), a pale
green powder as opposed to a crystalline salt. Copper in the presence of
atmospheric moisture and carbon dioxide produces copper carbonate. Cupric
oxide is black by the way, cuprous oxide is red.

This green stuff seems very similar to the usual sort of thing which
happens to Copper if left outside / in the damp,

That's because it's the same stuff.


Brilliant, thanks for this. I'm happy with what I have done electrically
(you should have seen the circuit's readings before I started!) I was
just trying to satiate my curiosity about the physical process involved.
If I may ask a cheeky follow-on question...

....the screw terminals in the socket are... ummm... brass I should
think. Some sockets seem to be all brass, or maybe brass and
copper, others have brass terminals riveted (in the case of the Earth
which can be seen) onto steel.

Damp (plus unknown contaminants) plus copper plus brass plus pressure
equals ?

Yes, I have seen very blackened exposed copper in this combination, but
usually cutting back an inch or so reveals something approaching shiny
:-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Where's my 640Meg SIMM? I want to run Excel!

W

Wow. I realised that those things were pretty big, but had not
realised that they were that high.

Eaves level on the house is my limit and I'm not comfortable then.

I hope that you're well rewarded for this work.....

Yep, all the water I can drink for free

Unbelievable that someone could do that without falling off.

Dont worry, its not the falling off that kills you its the sudden stop at the
end ! ( old linesmans joke )
I have just come back from London and looking at the high rise buildings and
tower blocks wondering how they fix satellite dishes 5 ,6 ,7 , 8 floors up the
side of building intrigues me. i dont think the windows open enough to dangle
out so wether the fitters abseil down I dont know. Any one else know ?

On 04 May 2004 18:52:42 GMT, in uk.d-i-y
(Wheelbarrowbob) strung together this:

I have just come back from London and looking at the high rise buildings and
tower blocks wondering how they fix satellite dishes 5 ,6 ,7 , 8 floors up the
side of building intrigues me. i dont think the windows open enough to dangle
out so wether the fitters abseil down I dont know. Any one else know ?

The same way the window cleaners get down the side of the building.
--

SJW
A.C.S. Ltd.