Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?

On 31 Aug 2006 00:33:06 -0700, "davidlaska"
wrote:

Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?

The correct terminology is multi conductor "cable." With four single
strand wires.

Phone company uses lots of different wire - but 30 awg sounds too
small, try 22-20 gauge. Or here's a novel idea - measure the diameter
and look it up.

Make sure it is copper also - they do use other materials, especially
when they want an indestructible cable.

Or if you can get at the ends, measure the resistance and calculate
your voltage drop.


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default wrote:
On 31 Aug 2006 00:33:06 -0700, "davidlaska"
wrote:

Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?

The correct terminology is multi conductor "cable." With four single
strand wires.

Phone company uses lots of different wire - but 30 awg sounds too
small, try 22-20 gauge. Or here's a novel idea - measure the diameter
and look it up.

Make sure it is copper also - they do use other materials, especially
when they want an indestructible cable.

Or if you can get at the ends, measure the resistance and calculate
your voltage drop.
Measuring the diamator needs a good caliper but I could do resistance. Then I have v, amps, r for a formula. I would guess 10 % . Thanks for the ballpark figure on phone line sizes.

You really do not need to know the guage of the wire.
Logic would suggest that you utilize the 500' roll, run the 12 volts through
it, load it with your 200ma load and measure the voltage drop.... then you
can interpolate the approximate voltage drop for any length including the
200 ft length you are planning to use.
The 500 ft length will not permit the intended load to reach the full 200ma
because of the additional voltage drop of the extra length but this method
will get you close....... you could use a variable resistor to create
exactly a 200ma load and then your interpolation would be dead on.
If you use a resitance chart for the guage (size) of the wire then you will
have to multiply by TWO because your circuit will use two wires.
Best Regards,
Daniel Sofie
\- - - - - -




----- Original Message -----
From: "davidlaska"
Newsgroups: sci.electronics.repair
Sent: Thursday, August 31, 2006 12:33 AM
Subject: What AWG is "Drop on ground" phone line wire?


Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?

"davidlaska" wrote in news:1157009586.378668.258860
@p79g2000cwp.googlegroups.com:

Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?


If it really is copper wire, then the following numbers might be helpful.

20 AWG, .032 in dia, 10.15 ohms per 1000 ft, 2 ohms per 200 ft., at 0.2
amp the voltage drop will be 0.4 volts each wire, total 0.8 volts for
two-wire setup. (If you parallel two wires out and two wires back,
making use of all 4 wires in the cable, total voltage drop is 0.4 volts.)

22 AWG .025 in dia, 16 ohms per 1000 ft. 3.2 ohms per 200 ft., total
voltage drop 1.2 volts (2 wire) or 0.6 volts (4 wire).

24 AWG .020 in dia, 25.7 ohms per 1000 ft, 5 ohms per 200 ft., total drop
2 volts (2-wire) or 1 volt (4-wire).

26 AWG .016 in dia, 41 ohms per 1000 ft, 8 ohms per 200 ft., total drop
3.2 volts (2-wire) or 1.6 volts (4-wire).

As you can see, you might get by with 20 or 22 AWG, but 26 AWG or smaller
is totally hopeless.

Wire data from http://www.powerstream.com/Wire_Size.htm

Jim Land (NO SPAM) wrote:
"davidlaska" wrote in news:1157009586.378668.258860
@p79g2000cwp.googlegroups.com:

Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop . I am guessing 30 AWG?


If it really is copper wire, then the following numbers might be helpful.

20 AWG, .032 in dia, 10.15 ohms per 1000 ft, 2 ohms per 200 ft., at 0.2
amp the voltage drop will be 0.4 volts each wire, total 0.8 volts for
two-wire setup. (If you parallel two wires out and two wires back,
making use of all 4 wires in the cable, total voltage drop is 0.4 volts.)

22 AWG .025 in dia, 16 ohms per 1000 ft. 3.2 ohms per 200 ft., total
voltage drop 1.2 volts (2 wire) or 0.6 volts (4 wire).

24 AWG .020 in dia, 25.7 ohms per 1000 ft, 5 ohms per 200 ft., total drop
2 volts (2-wire) or 1 volt (4-wire).

26 AWG .016 in dia, 41 ohms per 1000 ft, 8 ohms per 200 ft., total drop
3.2 volts (2-wire) or 1.6 volts (4-wire).

As you can see, you might get by with 20 or 22 AWG, but 26 AWG or smaller
is totally hopeless.

Wire data from http://www.powerstream.com/Wire_Size.htm

The unit I am power is a sony bullet cam that uses a switching power
source, I suppose that means it would be more susceptible to voltage
drops. I wonder if on a hot sunny day if voltage was border line in
the cool morning, it would drop further during the afternoon when
things get the hottest. From all the help here, the easiest less
thinking approach is to take a voltage reading at the end of the line
with a 20 watt 12v light and see the drop and compensate any number of
ways to get close enough for the the camera to be safely powered up.

In article .com,
davidlaska writes

Phone company left me 500' of 4 strand telephone wire with a heavy
insulation that is rated tough enough where all you need to do is role
it out on the ground ( no burying or hanging or conduits needed). I
want to draw 12v dc at 0.2 amps (one fifth of a amp) over 200' and
want to calculate or know the voltage drop

The cable's 4 wire and you only want 2 (12v + and -), correct?

If you parallel up the cores to make 2 wires of 2 cores, that'll reduce
the resistance of the cable and thus the voltage drop.

I did this with a long run to some garden lights. With 2 wires, the
voltage drop made the lamps dim. Fortunately, I'd run 4-core 1.5mm^2
cable out to the lights (it was in my spares pile) and so was able to
reduce the voltage loss by doubling up the cores. This made the lamps
run at about normal brightness.