Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 03-30-2008, 12:09 PM   #16
Idiot Emeritus
 
Join Date: Mar 2008
Location: Fernley, Nevada (near Reno)
Posts: 1,596
Share |
Default

Wire size


Thanks, Marc. I'll write that down as a reference. Very handy when working with metric equipment.

In the above example, a 5.4 anp motor about 600' away, #8's would be my choice as well.

Rob

micromind is offline   Reply With Quote
Old 03-30-2008, 01:13 PM   #17
Cow
Member
 
Join Date: Jan 2008
Location: Oregon
Posts: 116
Default

Wire size


Quote:
Originally Posted by idoelectric View Post
#6 copper stranded is good for 30 amps at 120v for a distance of 500 ft.

I'm not sure where the 7 amps came from?


Cmils= 2 x K x I x D / VD
I believe you're mistaken. Use the formula you posted and see what you come up with. Unless you're shooting for 15% VD?


FYI, the 7 amps was calculated using this formula:

I=(CM x VD)/(2 x K x D)
Cow is offline   Reply With Quote
Old 03-30-2008, 03:45 PM   #18
My License Ain't 4 Sale..
 
Join Date: Feb 2008
Location: Atlanta, Ga/Hamilton, Al
Posts: 1,813
Default

Wire size


Quote:
Originally Posted by elkangorito View Post
I don't know about the USA but calculating the voltage drop for a given cable length & current, is not a simple process in Australia.
I generally use the formula VD = (2KxIxD)/cm

where K is a typical value for the resistivity of copper, 12.9 ohms/cm-ft
I is the current
D is the distance, in feet
and cm is the circular mils of the wire.

I transpose the equation into cm = (2KxIxD)/VD

where VD is 3.6V for 120 V or 7.2 for 240 V.

So if I know the current, this tells me the wire size in circular mills. I can then select from a chart of standard gauges to the nearest size.

Our wire ampacities are selected from a table of based on what conditions the wire is used in. Most typically, it is based on no more than 3 conductors in a conduit of cable, or directly buried in earth. There are other tables for free air and other conditions.

InPhase277

InPhase277 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Circuit breakers and wire size stan 41943 Electrical 19 03-06-2008 02:29 PM
Wire size and Breaker size for remodel ?? Skydmark1 Electrical 12 12-15-2007 05:00 PM
Wire size for distance Question fburke Electrical 4 07-28-2007 09:29 AM
Wire size for Central Air mwtuck HVAC 2 12-01-2006 05:06 PM
wire size wire to 10kw furnace? lochcarron Electrical 1 04-10-2005 07:43 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.