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clc19chase
05-31-2008, 12:09 AM
trying to wire a 2 hp pump pulling 11.2 amps at 23o volts. wire will be running 300 ft from breaker to pump. should I use 10 ga. or 8 ga. wire to power the pump.

Wet_Boots
05-31-2008, 12:37 AM
http://www.stealth316.com/2-wire-resistance.htm

You're probably okay with 10 gauge copper, figuring that the starting current is double that of the running current.

advancedlawnsolutions
05-31-2008, 12:55 AM
I ran into this same scenario last year. Same distance to. 10 gauge is fine. Direct burial cable, be sure to put it plenty deep.

clc19chase
05-31-2008, 08:39 AM
Im still uncertain. I have a very experienced and reputable electrician saying 10 want work. But the home owner says the guy he knows (electrician) says 10 is plenty. I will be putting in thr system next week and dont want to start a "finger pointing contest" if 10 ends up too small. thanks for any additional info.

Wet_Boots
05-31-2008, 08:47 AM
If the voltage drop is less than 10 volts upon starting, then you should be okay, unless you get a low of brownouts in your area.

Kiril
05-31-2008, 09:09 AM
If the voltage drop is less than 10 volts upon starting, then you should be okay, unless you get a low of brownouts in your area.

using that page you referenced boots, and assuming a 24 amp startup, 600 feet of #10 gives you a drop of 14.6 volts

Wet_Boots
05-31-2008, 09:28 AM
using that page you referenced boots, and assuming a 24 amp startup, 600 feet of #10 gives you a drop of 14.6 voltsTrue enough. I only used 300 feet to get a result, but 600 is proper for 'out and back' ~ I suspect you could still live with a 15 volt drop on 230, but there might be more specific info on some pages dealing with motors.

WalkGood
05-31-2008, 03:33 PM
True enough. I only used 300 feet to get a result, but 600 is proper for 'out and back' ~ I suspect you could still live with a 15 volt drop on 230, but there might be more specific info on some pages dealing with motors.

Is that a constant voltage drop or just at the momentary startup?

Hopefully he has a "standard" 240volt to start with.

Dirty Water
05-31-2008, 04:15 PM
Why exactly are you doing this and not an electrician?

Think of it this way, would you trust an electrician to size zone pipe?

Mike Leary
05-31-2008, 04:23 PM
Why exactly are you doing this and not an electrician?
Think of it this way, would you trust an electrician to size zone pipe?

I was thinking the same thing, two words: geek think. :hammerhead:

hoskm01
06-01-2008, 12:41 AM
Would it hurt to just use 8 and not fret?

WalkGood
06-01-2008, 01:10 AM
Would it hurt to just use 8 and not fret?

Just in the wallet.

clc19chase
06-01-2008, 10:45 AM
I am helping decide which size wire. His electrician is wiring up a new breaker and supposedly thinks 10 ga is "plenty". I will be trenching from breaker panel about 15 feet over to my main trench and customer requests that I run the power wire for the pump in this trench.
Will it cause a problem running the 8 ga in the trench, or should it have a seperate trench. thanks guys for the input.

Wet_Boots
06-01-2008, 10:51 AM
Are you using a conduit for this underground wire? If so, shouldn't be a problem sharing a trench.

Mike Leary
06-01-2008, 03:46 PM
Are you using a conduit for this underground wire? If so, shouldn't be a problem sharing a trench.

These days, conduit should be spec'd on all jobs, code or no code.

Wet_Boots
06-01-2008, 03:54 PM
It's a pretty long run for conduit. I wouldn't want to be the guy who has to pull the wire.

Mike Leary
06-01-2008, 04:04 PM
It's a pretty long run for conduit. I wouldn't want to be the guy who has to pull the wire.

That's what "pull boxes" were invented for: every 30 to 50' depending on sweep ells. :hammerhead:

Wet_Boots
06-01-2008, 05:05 PM
Too much work. Unroll some UF in the trench and call it done.

Dirty Water
06-01-2008, 05:16 PM
Too much work. Unroll some UF in the trench and call it done.

A little wire lube and its easy.

Mike Leary
06-01-2008, 05:26 PM
A little wire lube and its easy.

Pulling building line with a shop vac works with a piece of plastic bag to get the first
run through, then heavier poly rope is pulled to each pull boxes; don't need
lube if it's done right. :clapping:

WalkGood
06-01-2008, 11:15 PM
Pulling building line with a shop vac works with a piece of plastic bag to get the first
run through, then heavier poly rope is pulled to each pull boxes; don't need
lube if it's done right. :clapping:

I used that trick 5 or 6 years ago. Observers thought I was wacky, until 1.2 seconds of shop vac and the piece of plastic bag with builders twine was in my hand.

Larger conduit makes it easier too.

AI Inc
06-02-2008, 05:25 AM
Pulling building line with a shop vac works with a piece of plastic bag to get the first
run through, then heavier poly rope is pulled to each pull boxes; don't need
lube if it's done right. :clapping:

No ya dont , but taping a q tip to the end of the wire sure does help.

nylan8888
06-02-2008, 06:20 AM
I am helping decide which size wire. His electrician is wiring up a new breaker and supposedly thinks 10 ga is "plenty". I will be trenching from breaker panel about 15 feet over to my main trench and customer requests that I run the power wire for the pump in this trench.
Will it cause a problem running the 8 ga in the trench, or should it have a seperate trench. thanks guys for the input.

I would let HIS electrician make the decision. It leaves you out of the equation if there is a problem. Also would not want the wire in my irrigation trench unless it is 12"-18" below everything else. Seems like it could be a future liability issue, new irrigation company 3 years from now out to repair a leak and the tech doesn't know and sinks a sharpshooter into it.