On Sun, 22 Jul 2012 04:40:38 +0000 (UTC), gregz
wrote:

" wrote:
On Jul 21, 8:15 pm, gregz wrote:
" wrote:
On Jul 21, 6:00 am, Frank Thompson wrote:
I've heard that there is a limited to the distance that a drop cord
for power equipment can be used. Beyond that limit there is risk to
damage the equipment being used. If this is true, what is this
length? My guess is that it depends on the
rating of the drop cord. Is there a source where I can determine
what size cord is safe at what distance?

If you google resistance of copper wire you will
find tables that give the resistance of wire per foot
for each gauge of wire. Then you can use ohms
law to calculate the voltage drop. Let's say the
wire has a resistance of .01 ohms/ft. Then 100
feet would have a resistance of 1 ohm. And if
the load on it is 5 amps, then it will have a voltage
drop of 5 volts. So, if you started out with 120v
at the receptacle, you have only 115V at the end
of the cord.

How about X2 , 200 feet round trip. ??

Greg



Doh! I left them electrons piling up there, didn't I?

You are correct. I only accounted for the voltage
drop on one length of wire, so it's actually 2x that
and you only have 110V at the load.







The rest is up to what the load is, do you really
have 120V at the receptacle, and how lucky
you feel. As a rough guide, you can use the
rule of thumb for residential wiring. 14 gauge for
15 amps, 12 gauge for 20.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

I do a bunch of stuff, but no harm yet. Run a 100 foot 12 gauge extension
cord out of garage, but the garage is fed with 85 foot, 10 gauge wire.
Small air conditioner works ok. At camp I ran the air conditioner with 100
foot 14 gauge extension into little trailer from big trailer.

During Xmas I have a 250 foot 18/16 extension to feed small set of lights.
Looks like lights without a house in sight.

Greg
The 110 volts at the end of the "drop cord" is only 110 volts if it
is connected directly to the panel - otherwize there is voltage drop
on the 14 g wires from the panel to the outlet as well,. And tha ASS
U ME s you have 120 volts at the panel under load - which is not a
given, as you can have voltage drops between the transformer and the
panel, which will vary depending on the over-all load on the panel at
any given time. - Current voltage on an unloaded branch circuit right
now at my house is 13.9 - 114 VAC with the AC not running. and
113.3-113.5 with the AC on. - 100 amp service 300 feet from the
transformer. About 222 at the AC unit disconnect 50 feet from the
panel on #12 cable.