May I thank all that gave me advice on this.
Went out today and we insulated wires two and three
from the top by using some plastic conduit that we
cut so as to slip it over before refastening the
wires to the posts.
Oh, and we insulated the wires of the posts at both ends.
Luckily this is a straight run fence, no gates or corners.

Put a jumper across the wires at the top of hill and got a reading
of thirty seven ohms.
So have decided to follow Spehro's plan and use two of
these http://www.jaycar.co.nz/productResults.asp?FORM=KEYWORD

And use the Linksys wallwart as well.
Am I right in believing that using two wires up and two
down would drop the overall resistance to eighteen ohms ?
Thanks again.

On Tue, 29 Apr 2008 22:48:46 +1200, grumpyoldhori
wrote:



May I thank all that gave me advice on this.
Went out today and we insulated wires two and three
from the top by using some plastic conduit that we
cut so as to slip it over before refastening the
wires to the posts.
Oh, and we insulated the wires of the posts at both ends.
Luckily this is a straight run fence, no gates or corners.

Put a jumper across the wires at the top of hill and got a reading
of thirty seven ohms.
So have decided to follow Spehro's plan and use two of
these http://www.jaycar.co.nz/productResults.asp?FORM=KEYWORD

And use the Linksys wallwart as well.
Am I right in believing that using two wires up and two
down would drop the overall resistance to eighteen ohms ?
Thanks again.



Yes





** Posted from http://www.teranews.com **

On Tue, 29 Apr 2008 22:48:46 +1200, grumpyoldhori
wrote:



May I thank all that gave me advice on this.
Went out today and we insulated wires two and three
from the top by using some plastic conduit that we
cut so as to slip it over before refastening the
wires to the posts.
Oh, and we insulated the wires of the posts at both ends.
Luckily this is a straight run fence, no gates or corners.

Put a jumper across the wires at the top of hill and got a reading
of thirty seven ohms.
So have decided to follow Spehro's plan and use two of
these http://www.jaycar.co.nz/productResults.asp?FORM=KEYWORD

And use the Linksys wallwart as well.

Your link is missing the keyword to search on.




Am I right in believing that using two wires up and two
down would drop the overall resistance to eighteen ohms ?
Thanks again.






Thank You,
Randy

Remove 333 from email address to reply.

On Tue, 29 Apr 2008 08:37:28 -0500, Randy wrote:

On Tue, 29 Apr 2008 22:48:46 +1200, grumpyoldhori
wrote:



May I thank all that gave me advice on this.
Went out today and we insulated wires two and three
from the top by using some plastic conduit that we
cut so as to slip it over before refastening the
wires to the posts.
Oh, and we insulated the wires of the posts at both ends.
Luckily this is a straight run fence, no gates or corners.

Put a jumper across the wires at the top of hill and got a reading
of thirty seven ohms.
So have decided to follow Spehro's plan and use two of
these http://www.jaycar.co.nz/productResults.asp?FORM=KEYWORD

And use the Linksys wallwart as well.

Your link is missing the keyword to search on.




Am I right in believing that using two wires up and two
down would drop the overall resistance to eighteen ohms ?
Thanks again.






Thank You,
Randy

Remove 333 from email address to reply.


No it's not search on the part number 95000.
** Posted from http://www.teranews.com **

On Tue, 29 Apr 2008 22:48:46 +1200, grumpyoldhori
wrote:



Put a jumper across the wires at the top of hill and got a reading
of thirty seven ohms.

37 ohms per km of 4 mm iron/steel wire strongly suggests a splice
that may be mechanically strong but has poor conductivity due to
corrosion.

clare at snyder dot ontario dot canada wrote:

No it's not search on the part number 95000.
** Posted from http://www.teranews.com **

Did you mean CAT. NO. MM2014?
http://preview.tinyurl.com/4zb3pj

--Winston

Don Foreman wrote:

37 ohms per km of 4 mm iron/steel wire strongly suggests Â*a splice
that may be mechanically strong but has poor conductivity due to
corrosion.

Yes, good point, I will put 4 mm copper wire jumpers
across all splices.
What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

Winston wrote:

Did you mean CAT. NO. MM2014?
http://preview.tinyurl.com/4zb3pj


Have ordered two CAT. No MM2005s.
Our Extra low voltage rules allow up to 50 volts AC,
but I am wary of any thing above thirty volts on bare
wires.

In article ,
grumpyoldhori wrote:

Winston wrote:

Did you mean CAT. NO. MM2014?
http://preview.tinyurl.com/4zb3pj


Have ordered two CAT. No MM2005s.
Our Extra low voltage rules allow up to 50 volts AC,
but I am wary of any thing above thirty volts on bare
wires.

This transformer is not center-tapped. It is multi-voltage tapped,
which is different. Try CAT. NO. MT2086 instead.

A 30-volt center-tapped transformer puts out two 15-volt lines by that
standard.

Before ground fault interrupters were invented, what one did on
construction sites was an isolation transformer with grounded output
centertap, so the voltage was +/- 50 VAC.

Joe Gwinn

grumpyoldhori wrote:

Don Foreman wrote:


37 ohms per km of 4 mm iron/steel wire strongly suggests a splice
that may be mechanically strong but has poor conductivity due to
corrosion.


Yes, good point, I will put 4 mm copper wire jumpers
across all splices.

Better to carefully clean and solder the steel splices rather than
have current going through dissimilar metal junctions.
This stuff is rusting away quickly enough. No need to speed up
that process.

Remember the flux! Remember to clean up with alcohol!


What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

Say 14.75 ohms for a km as a guess.
So a two wire loop of 1 km would total about 29.5 ohms.

--Winston

On Wed, 30 Apr 2008 11:25:46 +1200, grumpyoldhori
wrote:
Don Foreman wrote:

37 ohms per km of 4 mm iron/steel wire strongly suggests *a splice
that may be mechanically strong but has poor conductivity due to
corrosion.

Yes, good point, I will put 4 mm copper wire jumpers
across all splices.
What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

No, you should get a portable torch rig with some horsepower (Oxy-
Acetylene or Air-Acetylene or MAPP) and go silver-braze or silver
solder all the splice points - or even 60/40 lead/tin solder if you
don't worry about RoHS, but no acid flux unless you clean it up.

Get the resistance down enough, and 24V (AC or DC) at the bottom of
the hill will be enough to get 12VDC at the top (after regulating,
filtering and surge/lightning arresting).

I still say AC is better for longer distance work at low voltage,
but as always Your Mileage May Vary.

-- Bruce --

In article ,
Bruce L. Bergman wrote:

On Wed, 30 Apr 2008 11:25:46 +1200, grumpyoldhori
wrote:
Don Foreman wrote:

37 ohms per km of 4 mm iron/steel wire strongly suggests *a splice
that may be mechanically strong but has poor conductivity due to
corrosion.

Yes, good point, I will put 4 mm copper wire jumpers
across all splices.
What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

No, you should get a portable torch rig with some horsepower (Oxy-
Acetylene or Air-Acetylene or MAPP) and go silver-braze or silver
solder all the splice points - or even 60/40 lead/tin solder if you
don't worry about RoHS, but no acid flux unless you clean it up.

I would soft solder it, using whatever is used on copper pipes, to avoid
overheating and de-galvanizing the wires, promoting faster rusting.
Tinners flux (zinc chloride in HCl) will be needed. Plumbers grease
flux will not work on steel wire. Wash the joint off when done.

The splice joints are probably already too corroded and dirty to solder,
but there is no reason one cannot add jumpers around the existing
splices. Starting with open wire allows one to polish down to bright
metal before making the mechanical connection that will be soldered.
The splice should be the same kind of wire as the wire, to avoid setting
up a galvanic couple at each splice.


Get the resistance down enough, and 24V (AC or DC) at the bottom of
the hill will be enough to get 12VDC at the top (after regulating,
filtering and surge/lightning arresting).

I still say AC is better for longer distance work at low voltage,
but as always Your Mileage May Vary.

Another reason to prefer AC is to reduce corrosion. With DC, one strand
will soon be eaten away at the fence posts by galvanic corrosion due to
the inevitable leakage currents. With AC, the leakage is still there,
but there is no net transport of material.


Joe Gwinn

grumpyoldhori wrote:

What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

I figure about 7.7 ohms, based on 9.7 microohm-cm for resistivity of
iron.