Drop pipe and wire size

[Thatdarncat]

Hi Folks,
I have a 400' well with the static water pressure at 50" below the surface.
I want to use a 1-1/2 hp 120v pump, the reason for 120 volt is so that I can power it with a generator when the grid goes down during winter ice storms.
The well is about 75 feet from the service panel and I want to drop the pump to a depth of 380 feet.
What gauge wire do I need for the run? ( the pump comes with 130 ft of wiring) Or would I need larger gague the full run to the pump?
Lastly, could I used 3/4 ads flex pipe or should I stick to 1 inch ads pipe...the reason I would like to use 3/4 is I can get a continuous run of 3/4 pipe 400 ft long , while I can only get 300ft of 1 inch ads flex pipe whiltch would require a coupling point.
This is only for use in my small home of a family of three.
Thanks for any help you can toss my way!

 

[Bannerman]

I have a 400' well with the static water pressure at 50" below the surface.

I anticipate you mean the static water level is 50'.

A 240 volt pump will consume the same watts as a 120 volt version, but since the amperage will be 50% of a 120 volt version, that will allow lighter gauge wiring to be utilized.

A generator that will output 240 volts, will need to support fewer amps than a generator that will only output 120 volts even as the wattage will be identical.

 

[Sponsor]

 

[VAWellDriller]

I think you should look at the pump curve for that pump....anything you can get that CLAIMS to be 1.5HP and can run on 120 volts sounds like a piece of junk. I suspect that pump will not really be capable of doing anything should the water level drop to 380. Anything over 0.5 REAL HP will only come in 240 volt. If you were to want to run a 120 volt 1/2 HP submersible you would probably need 8 gauge wire.

 

[LLigetfa]

I would not use 3/4" pipe for that distance. Does it really need to be set that deep? As VA said, that pump you are spec'ing likely won't lift that high. PVC is another option.

They do make 240V generators.

 

[Reach4]

I think you should look at the pump curve for that pump....anything you can get that CLAIMS to be 1.5HP and can run on 120 volts sounds like a piece of junk. I suspect that pump will not really be capable of doing anything should the water level drop to 380. Anything over 0.5 REAL HP will only come in 240 volt. If you were to want to run a 120 volt 1/2 HP submersible you would probably need 8 gauge wire.

I suspect it does not offer a pump curve.

You should be able to find 500 ft spools of 1 inch, but I am not saying 1 inch is big enough... Menards does not sell to states where it does not have stores, but if it's available there, I am confident it will be available close-enough to you.
Search Results for "sidr" at Menards®

 

[Fitter30]

https://www.slpipe.com/product/drop-pipe/

https://www.inchcalculator.com/voltage-drop-calculator/
Heres two calculators

 

[Thatdarncat]

Thanks for the info, The well is 400 ft deep, 50 ft static water level with only 2 gpm replacement rate. ( Sorry about the goof up of 50 inches of water "pressure")

I would like to drop the pump as deeply as possible ( around 380 feet) to compensate for the replacement rate. We dont plan on a lot of water usage, and Im definitely not irrigating with that kind of well, just strictly home useage.....Our worst case scenario is a washing machine running and a shower or bath tub running, so if you folks dont think I need to drop that pump that deep, I would be happy not to wrestle that much drop pipe!

It looks like 1 inch poly is the way to go as far as water restriction! Thanks! No menards around here, but Lowes does sale it in 500ft rolls.. a lot of waste after 380...maybe I could sale the rest or get it in a 400 ft length....maybe 300ft and splice in another 80ft....lol I hate splicing.

I still like the idea of 20ft PVC drop pipe sections in case I have to pull the pump on day, instead of fighting a heavy octopus thats almost 400 feet long.
The 8 gauge wire is what I was seeing yesterday too for a 120v pump....I would like to go 120v but as you folks point out the wiring size and the combination of a junky pump might be just as costly. especially if I have to pull it every other year.

Yes the pump I was looking at was probably a junky made Chinese one, it said 1.5 hp and 390 max ft of head....I was also looking at a Gould, but had no idea the prices were so high...over a 1000 bucks!
I wish I could afford a Gould! Is there a well made pump that is somewhere between the two extremes of a junky Chinese pump and an American made Gould?

Probably 220v is the way to go. I already have 3 11o volt generators....lol I need another generator like a hole in the head.

 

[LLigetfa]

Yes the pump I was looking at was probably a junky made Chinese one, it said 1.5 hp and 390 max ft of head....

Not enough head to set it at 380 feet. It will not build enough pressure to shut off.

 

[Thatdarncat]

Not enough head to set it at 380 feet. It will not build enough pressure to shut off.

Thanks, what would you recommend ?
It looks like a two wire 220volt is the way to go ( I want to use the tried and true contacts pressure switch)

Its a six inch well and the static water level has remained the same for a year at 50ft, thats about 1.5 gallons per foot, if I dropped the pump to 250 ft that would give me 300 gallons available, ( minus static level) not counting the measly replacement rate, would that be a good depth to start off with? ( so as I dont get into a dry run situation and smoke the pump), or would every one just drop a rated pump to 380 and be done with it?

 

[VAWellDriller]

With normal household water use, you would be fine to set a 1HP 7 or 10GPM at 300 ft and have plenty of water. Most homes use 200 - 300 gallons /day so you would have more than a day or storage just in the standing water column. Grundfos 10sq10-290 would be a good fit. It would not quite build cutoff pressure if the water level dropped to 300, but it does have built in dry run protection.

 

[LLigetfa]

Grundfos 10sq10-290 would be a good fit.

I thought you had a low regard for the Grundfos 2-wire motor?

 

[Reach4]

I thought you had a low regard for the Grundfos 2-wire motor?

I think that was for the 4-inch pumps. SQ are a different thing, and have no 3-wire version.

 

[VAWellDriller]

Right...it's the 4" 2wire motors I had an issue with in the last. They have probably fixed it but I have a long memory and a habit of carrying a grudge when I have problems with a product and have to go back and do warranty work that's not my fault.

I'm still holding my record than I have NEVER seen a 3" grundfos fail yet...motor or wet end. That streak has to come.to an end sometime but hasn't yet. I'm using them for almost all of my small work right now.