----- Original Message ----- From: "Thomas C. Sefranek" To: Sent: Wednesday, May 29, 2002 2:21 PM Subject: Re: [EE]:formula/link for current capacity of wire (AC) > On 29 May 2002 at 11:45, Micro Eng wrote: > > > ok..power guys... > > > > Whats the formula, given that I have the current and voltage, to calculate > > the wire size that is required. > > > > I'm talking large amounts of current...like 833Amps @120VAC > .05093 / 1,000 * 833 * 40 = 1.7 volts loss for 4/0, just over 1%. > > Wire size is not determined by voltage. > How much POWER are you willing to loose in the wire? > How much VOLTAGE loss can you stand? > > > > I know for 200A, I need a 4/0 wire. > Perhaps: > > 4/0 wire is .05093 ohms per 1,000 feet. > For 40 feet, (20' there and back) you get .002 ohms > @ 200 amps, the voltage drop is .4, 200 A * .4 V = 80W Note that 80W of heat are going to be generated. This is about 2W / foot which shouldn't make the wire too hot... Bob Ammerman RAm Systems -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.