ampacity

[cem-bsee]

NO wire of any size nor voltage rating has an AMPACITY rating!!!!

Wire MAY have a voltage rating. Wire WILL have a maximum conductor temperature rating.

Lots of wire has no voltage rating = most service drop cable, street lighting cable, lots of welding cable, etc.

ampacities are derived from the installation environment and the conductor temperature rating.

the use of ONLY the 60C conductor temperature ratings equates to the cheapest everday operating costs, but not the wire cost.

[tecman]

True there is not a "current rating" per se, but for a given insulation temperature rating, NEC defines a maximum allowable current. Article 310 has a series of tables titled "Ampacity Ratings of Single Conductors..."

It's the NEC definition.

paul

[beenthere]

Check the NEC, i beleive its 440.? motor loads and wire rating.
Condensers are consider a motor load only.

[Wild Leg]

I did a little search on "ampacity".

from http://www.powersource.net/glossary.htm
Ampacity - The current carrying capacity, expressed in amperes, of a conductor under stated thermal conditions.

from http://www.jeffersonelectric.com/techglos.html
Ampacity: The current-carrying capacity of an electrical conductor or device.


This one is a pretty good read...
from http://www.allaboutcircuits.com/vol_1/chpt_12/3.html
COPPER CONDUCTOR AMPACITIES (table)


A combination of wire size, insulation type, location, and other factors determine circuit ampacity.

That's my story and I'm stickin' to it. :D

[tecman]

Originally posted by beenthere
Check the NEC, i beleive its 440.? motor loads and wire rating.
Condensers are consider a motor load only.

For HVAC you are correct. I was only citing 310 for the usage of the term "Ampacity"

paul