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Old 06-12-2008, 09:18 AM   #1
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Wire size 10ga 8ga or something else


I am putting in a new well with 1hp pump that draws between 7.5 and 12 amps @ 220volts. I need to pull about 400' of wire underground in pvc conduit from breaker box in barn, using 20amp 2 pole breaker Should I use 10/2 with grnd, 8/2 with grnd solid romex or something else?

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Old 06-12-2008, 09:47 AM   #2
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Wire size 10ga 8ga or something else


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I am putting in a new well with 1hp pump that draws between 7.5 and 12 amps @ 220volts. I need to pull about 400' of wire underground in pvc conduit from breaker box in barn, using 20amp 2 pole breaker Should I use 10/2 with grnd, 8/2 with grnd solid romex or something else?
you are going to have a hell of a time pulling 400' of romex through pipe. You should use THWN. If you were to use romex, make sure it is UF cable. 8AWG is going to get expensive at that distance, but that is what you should go with.

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Old 06-12-2008, 10:03 AM   #3
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"you are going to have a hell of a time pulling 400' of romex through pipe"

I pulled 250' of 12/2 with ground thru 1/2" conduit to feed the light at the pond last week. First I laid out the wire then tied a string and weight to one end, dropped the weight thru the pipe one length at a at time and walked to the other end glueing one at a time. It took awhile but when you work alone you have to use your head and not your back.

As for UF, my worry is my brother snagging the wire the ditch digger on the tractor, I know the pipe can be cut but not as easily as the wire alone.

If 8/2 with ground is what I need then it is what I need to use.
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Old 06-12-2008, 10:18 AM   #4
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hd82, No disrespect meant towards you, but why in the world would you even consider pulling cable through that long run. You say "Romex". If you used NM cable (romex) in that conduit, it is a violation. Uf would not be a violation. Buried conduits are considered wet locations and you must use wire rated for wet locations. 250" foot of cable in a 1/2" conduit. You must really like to work hard.
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Old 06-12-2008, 10:37 AM   #5
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hd82, No disrespect meant towards you, but why in the world would you even consider pulling cable through that long run. You say "Romex". If you used NM cable (romex) in that conduit, it is a violation. Uf would not be a violation. Buried conduits are considered wet locations and you must use wire rated for wet locations. 250" foot of cable in a 1/2" conduit. You must really like to work hard.

I have to pull that far because the pump isn't solar powered. The barn is the nearest source of power at this time, other than that I would have to come from the power company pole which is 1,000 ft, drop a service pole and meter.
And besides I have more time than money so working hard isn't bad if you work smart.
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Old 06-12-2008, 11:29 AM   #6
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Regardless, you CANNOT use romex/nm in that conduit. You MUST use THWN or UF.
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Old 06-12-2008, 04:54 PM   #7
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I am putting in a new well with 1hp pump that draws between 7.5 and 12 amps @ 220volts. I need to pull about 400' of wire underground in pvc conduit from breaker box in barn, using 20amp 2 pole breaker Should I use 10/2 with grnd, 8/2 with grnd solid romex or something else?

To figure out what size circuit breaker is required you take the FLC of the motor and and multiply by 250%, so a 1HP motor is 8.0 amps at 230volts, 8 FLC x 250% = 20A, This is your short-circuit and ground fault protection.

To find out conductor size, you would take the FLC and multiply by 125%, so 8 FLC x 125% = 10 amps, so you could use a #14 awg, except for the voltage drop issue at 400'.

I have a franklin well pump book which already figured out the recommend wire size and distance and you can go, A 1 HP pump at 230v at a distance of 400' can use # 12 copper, # 10 is good for 630'


Now I dont know if the wire run to the barn is big enough to handle the voltage drop, but if you tell me how far the barn is to the meter and the wire size I can give you the correct AWG to run.

Last edited by chris75; 06-12-2008 at 04:57 PM.
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Old 06-12-2008, 06:08 PM   #8
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hd82...lolol...

I gotta laugh and tip my hat to you. The thought of you pulling the pipe and not the wires is hilarious! (your a genius!)

That said, it ain't code. You need to run individual wires in that conduit. Like hard work? in a worse case I would have stripped the Romex! (here in Canada it's made with THHN!

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Old 06-12-2008, 06:51 PM   #9
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working hard isn't bad if you work smart.



What I think you meant to say was, "I work hard because I don't work smart."

If you want to sleeve 400' of #8 romex one 10' stick of pvc at a time go right ahead. I think I'd stick with stranded THWN, a vacuum, a baggie and some pull string. But I don't have all day......
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Old 06-12-2008, 09:32 PM   #10
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I would have no problem at all with running a 1HP pump at 230 volts on #12's 400' away. You'll lose about 12 volts in the wire, most motors will operate satisfactorily at +or- 10% of their nameplate voltage. It's likely stamped 230 volts, so losing 23 volts would be OK.

Starting current on a 1HP motor at 230 volts will be about 45 amps. You'll lose about 60 volts when starting. I know this sounds like alot, but for a centrifugal pump, it'll work just fine. A centrifugal pump starts with very little load on the motor, most of the load occurs when it's almost at full speed. This is also the point when the motor can produce the most HP at the lowest voltage. If you were trying to start something fully loaded (like a grain auger, or an air compressor, for example), then I'd recommend #10's or maybe even #8's.

I'd pull THWN in conduit. It's designed to be pulled in conduit, NM is not legal, and UF would be very hard to pull. You'll need 3 wires, two hots that go to the breaker, and one ground. All 3 will need to be #12 or larger. The ground will need to be green. I'd recommend black and red for the other two. (Not required, just sort of an industry standard.)

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Old 06-13-2008, 05:16 AM   #11
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To figure out what size circuit breaker is required you take the FLC of the motor and and multiply by 250%, so a 1HP motor is 8.0 amps at 230volts, 8 FLC x 250% = 20A, This is your short-circuit and ground fault protection.

To find out conductor size, you would take the FLC and multiply by 125%, so 8 FLC x 125% = 10 amps, so you could use a #14 awg, except for the voltage drop issue at 400'.

I have a franklin well pump book which already figured out the recommend wire size and distance and you can go, A 1 HP pump at 230v at a distance of 400' can use # 12 copper, # 10 is good for 630'


Now I dont know if the wire run to the barn is big enough to handle the voltage drop, but if you tell me how far the barn is to the meter and the wire size I can give you the correct AWG to run.
Thanks,
As for as the meter at the barn, it has its own meter on the barn and a 2oo amp box so this isn't a problem.

I can come out of the box on a 30amp breaker then at the pump put a small box with a 20amp to the pump?

12 or 10 thwn with a ground? I feel safer with the 10, cost in this case should not be that much different? Either one should go easily in 1/2" pvc conduit, perhaps I'll walk two or three lengths at a time, I don't need that much exercise to make that trip 80 times.

This is for the gentleman that suggested the vacuum, I did have power to run a vac, did the work in the evening and not hard at all.
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Old 06-13-2008, 09:21 AM   #12
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Wire size 10ga 8ga or something else


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"I pulled 250' of 12/2 with ground thru 1/2" conduit to feed the light at the pond last week. First I laid out the wire then tied a string and weight to one end, dropped the weight thru the pipe one length at a at time and walked to the other end glueing one at a time. It took awhile but when you work alone you have to use your head and not your back.
A code violation to do it this way. You must assemble the conduit first and then pull the wire. The glue could damage the wire insulation. You could feed the pull rope this way if you like and hope it doesn't get glued into the conduit.
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Old 06-13-2008, 11:31 AM   #13
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Quote: I would have no problem at all with running a 1HP pump at 230 volts on #12's 400' away. You'll lose about 12 volts in the wire, most motors will operate satisfactorily at +or- 10% of their nameplate voltage. It's likely stamped 230 volts, so losing 23 volts would be OK.

I personally would not do it this way unless the motor is rated for 208 volts. 120/208/230.

Quote: I can come out of the box on a 30amp breaker then at the pump put a small box with a 20amp to the pump?

No. You need a 20 amp breaker for the run, no need for another breaker at the pump. You may need a disco at the pump depending on your local rules.
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Old 06-13-2008, 12:35 PM   #14
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Sounds like a rural area to me. I am only a do-it yourselfer and NOT an electrician,,but found this out the hard way.
Gophers and groundsquirrels etc LOVE to chew on underground wires,,, it takes 2" minimum to keep there jaws from getting around it and they can actually bite thru smaller pipe.
I ran one 12-2 w/gr. 1200 feet in 2 " conduit just for THAT reason. If you dont like doing it over,or digging it up again use the larger gopher proof size.
I had electric fence run 20' thru 3/4" conduit shallow underground,,it was a gopher magnet and lasted less than a year!!

My electrian direct buried some wires once,he said he would just dig it up and fix it when the gophers ate it,,,sure at MY expense,,,plus the damage he does and the resulting repairs of those gets expensive!!
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Old 06-14-2008, 04:58 AM   #15
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Sounds like a rural area to me. I am only a do-it yourselfer and NOT an electrician,,but found this out the hard way.
Gophers and groundsquirrels etc LOVE to chew on underground wires,,, it takes 2" minimum to keep there jaws from getting around it and they can actually bite thru smaller pipe.
I ran one 12-2 w/gr. 1200 feet in 2 " conduit just for THAT reason. If you dont like doing it over,or digging it up again use the larger gopher proof size.
I had electric fence run 20' thru 3/4" conduit shallow underground,,it was a gopher magnet and lasted less than a year!!

My electrian direct buried some wires once,he said he would just dig it up and fix it when the gophers ate it,,,sure at MY expense,,,plus the damage he does and the resulting repairs of those gets expensive!!
No gophers here but I do have a two legged squirrel that drives a Ford 3000 tractor (by brother) that is constantly digging up the ground! Not even 2" is safe with him around, I'm thinking of putting a winch on the tractor as he continualy gets the tractor stuck in the ditches he digs around the 18 acres we have.

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