Wondering what size wire is needed for the following:
2hp pump – specs say 18 amp draw
about 400′ from panel to pump location
12 gauge would handle a short distance, but I don’t know how much bigger to go.
TIA
Bear
Wondering what size wire is needed for the following:
2hp pump – specs say 18 amp draw
about 400′ from panel to pump location
12 gauge would handle a short distance, but I don’t know how much bigger to go.
TIA
Bear
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Replies
http://eduhosting.org/windpics/wgwire.html
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
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
Assuming the voltage for the 2hp pump is 240vac, the calculated wire size comes out to #6.
Yes, the pump is rated at 230v.Bear
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.
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.
call me tripped. Thanks for the correction/education. So that coems out ot a 6ga CU or 4ga AL?
7g not an electrician
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
Thanks for the replies. Surprising how much bigger it needs to be.Bear
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
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.
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.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill, the spec sheet for this pump shows start amps @ 63, and max. amps @ 18.Bear
I need to get my glass checked.I read it as 13 amps in the orginal message..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.