Replies

1. 
   brucet9 | Apr 14, 2008 11:32pm | #1

   http://eduhosting.org/windpics/wgwire.html

   BruceT
2. 
   Stuart | Apr 15, 2008 12:04am | #2

   Here's a voltage drop calculator - just plug in the numbers and hit calculate.  Size the wire to keep the voltage drop less than 3%.

   http://www.csgnetwork.com/voltagedropcalc.html

1. 
   jarhead2 | Apr 15, 2008 02:23pm | #3

   Wow, a 3AWG wire, 400ft?  Talk about expensive! 

    

    

    

   “Some people wonder all their lives if they've made a difference. The Marines don't have that problem.”                Reagan....

   Failure is the condiment that gives success its flavor. -Truman Capote

1. 
   Stuart | Apr 15, 2008 02:34pm | #4

   Assuming the voltage for the 2hp pump is 240vac, the calculated wire size comes out to #6.

1. 
   bearmon | Apr 15, 2008 04:12pm | #6

   Yes, the pump is rated at 230v.Bear

2. 
   john7g | Apr 15, 2008 03:34pm | #5

   You sure you're doing the calculator right?  Notice the entry for Enter 1/2 Total Circuit Length ?  When I ran the calcs @ 240v it comes up with 8ga with a 2.3% loss. 

1. 
   Stuart | Apr 15, 2008 04:26pm | #7

   That 1/2 total length thing can trip people up.  If it's 400 feet from the source to the motor, the total length is 800 feet since the circuit goes out and back, so 1/2 total length equals 400 feet. 

1. 
   john7g | Apr 15, 2008 04:34pm | #8

   call me tripped.  Thanks for the correction/education. So that coems out ot a 6ga CU or 4ga AL?

   7g not an electrician

2. 
   Stuart | Apr 15, 2008 04:45pm | #9

   Yup, 6 awg copper or 4 awg aluminum.

   Edited to add:  There are a number of online voltage drop calculators out there on the Web, some of them are worded a little differently.  For example, instead of asking for one half the total length, this one asks for the distance in feet one way (which is really the same thing but maybe less confusing); you can enter the numbers there and get the same answer.  http://www.elec-toolbox.com/calculators/voltdrop.htm

   Edited 4/15/2008 9:49 am by Stuart

3. 
   bearmon | Apr 15, 2008 05:52pm | #10

   Thanks for the replies.  Surprising how much bigger it needs to be.Bear

2. 
   jarhead2 | Apr 16, 2008 04:23am | #12

   I calculated it at 120V.........

   The 240 sure helped things out! 

    

    

    

   “Some people wonder all their lives if they've made a difference. The Marines don't have that problem.”                Reagan....

   Failure is the condiment that gives success its flavor. -Truman Capote

3. 
   renosteinke | Apr 15, 2008 06:03pm | #11

   400 ft? 18 amp? "Seat of my pants" guesstimate says to use #8, run it in at least 1" pipe (1 1/4 is much better), and have a pull box every 90 ft.

   The 'pull box' is a fiberglass handhole, about the overall size of a 5 gal bucket, that is open on the bottom. The ones usually used for sprinklers are not stout enough - get the real thing.

   Outdoor "bell boxes" are not intended for direct contact with earth, corrode away quickly, and don't have enough room for your wires.

   Bury the pipe at least 2 ft deep .... and come up into the bottom of the handholes. This will keep the pipe away from the gardeners' shovel.

   I frown upon the use of UF cable, since you'll have to dig it up to fix or replace it. Another advantage of pipe is that, if needed, you can later pull additional wires. Being that far from a building ... chances are you'll someday want a light, or a receptacle, or to add another pump someday. Pipe gives you the flexibility to do so with ease.

4. 
   BillHartmann | Apr 16, 2008 05:43am | #13

   Your numbers don't make sense.

   The NEC table show 13 amps for a 230 v (240) 2 hp motor.

   And most motors today are somewhat less than that.

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   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
1. 
   bearmon | Apr 16, 2008 04:26pm | #14

   Bill, the spec sheet for this pump shows start amps @ 63, and max. amps @ 18.Bear

1. 
   BillHartmann | Apr 16, 2008 09:09pm | #15

   I need to get my glass checked.I read it as 13 amps in the orginal message..
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   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.