Confirming correct voltage

[nizak]

I have a job that has an existing well pump. It was operational up to a year ago. The cottage it was serving has been demolished and a new one built in its place.

No info on pump. Found a 10/2 UF cable buried near where it would have entered the old dwelling.

Anyway to determine motor voltage without pulling the pump?
Don’t know the HP either.

Thanks

 

[Hv&Lv]

How old?
Without pulling the pump you could try 120V and check amps/water flow. (If there is any water flow)
Then go to 240V.

 

[Little Bill]

The 10-2 sounds like it was 240V. Most pumps that I have dealt with were 240V. However, I wouldn't want to connect it to 240V without knowing for sure.

 

[ptonsparky]

It needs a controller. Get a well guy involved, unless you want to pay for one on your dime.

 

[LarryFine]

I agree that 240v is the norm, but the #10 suggests 120v, unless the run is long.

With the house and controller gone, there's no other way to be sure but pull it.

Unless you can somehow find whomever installed and/or serviced it in the past.

 

[nizak]

It needs a controller. Get a well guy involved, unless you want to pay for one on your dime.

Good point. It needs a bladder tank and piping into the dwelling. I will take it from there.

 

[Little Bill]

I agree that 240v is the norm, but the #10 suggests 120v, unless the run is long.

With the house and controller gone, there's no other way to be sure but pull it.

Unless you can somehow find whomever installed and/or serviced it in the past.

How does #10 suggest 120V?

 

[LarryFine]

How does #10 suggest 120V?

For a load of a given power, halving the voltage required double the current.

A #10 is more likely to have been chosen for a 115v motor than a 230v motor.

I have never seen a 115v well pump nor one that required larger than #12.

 

[rambojoe]

It needs a controller. Get a well guy involved, unless you want to pay for one on your dime.

Do this. Get the well company, they may have a sticker in the starter- might be in building dept records.
Its probably 2 pole- and it will not fire up unless you are familiar w/wells...

 

[Dennis Alwon]

If you pull it you may want to test the pump before you put it back,

 

[Little Bill]

For a load of a given power, halving the voltage required double the current.

A #10 is more likely to have been chosen for a 115v motor than a 230v motor.

I have never seen a 115v well pump nor one that required larger than #12.

I understand the Ohm's Law part.
Your last two sentences contradict each other.

 

[LarryFine]

Your last two sentences contradict each other.

Let me try again:

A #10 is more likely to have been chosen for a 115v motor than a 230v moto

I would be more likely to select #10 for a 115v motor than for a 230v motor of the same HP.

Thus, the #10 suggests a 115v pump.

I have never seen a 115v well pump nor one that required larger than #12.

I have never seen a 115v well pump, and I have never seen a pump that required larger than #12.

Thus, the #10 suggests a 115v pump.


Combining these suggests the lower-voltage motor.

But I still wouldn't base the solution on just my observations.

 

[Hv&Lv]

I would simply put 120 to it and try it.
Don’t work, try 240.
If you got to pull it anyway what's the issue with it being burnt up?

 

[kwired]

Let me try again:


I would be more likely to select #10 for a 115v motor than for a 230v motor of the same HP.

Thus, the #10 suggests a 115v pump.


I have never seen a 115v well pump, and I have never seen a pump that required larger than #12.

Thus, the #10 suggests a 115v pump.


Combining these suggests the lower-voltage motor.

But I still wouldn't base the solution on just my observations.

You haven't seen many submersibles then

I know of two I ran power to last fall that have 6 AWG run to them. IIRC they were 5 hp three phase 240 volts. Well guy's tables suggested 6 AWG for the total length in this application, most of which was down the well casing.

Have connected many that are 2 HP three phase and well guy ran 10 AWG down the well casing, for voltage drop reasons.

Old school well guys might only ran 12 to them but many those running them on VFD's are very particular, they won't be covered by warranty if they don't follow instructions and they often request me to run larger supply conductor to the controller than I normally would select.

 

[hillbilly1]

Around here, #10 is ran as default. The well drillers usually run the pipe and wire to the house, they buy the wire in bulk, so they use it for any pump 1/2 to 1 hp. Most pumps are three wire, but there are two wire pumps, but most of those are under 3/4 hp. Most are 240 volt, with jet pumps mostly being 120 volt. If it is a three wire pump, it’s most likely, but not always 240 volt. Then you just have to figure out the HP. I think Franklin pump has a resistance chart to calculate what HP it is.

 

[hillbilly1]

You haven't seen many submersibles then

I know of two I ran power to last fall that have 6 AWG run to them. IIRC they were 5 hp three phase 240 volts. Well guy's tables suggested 6 AWG for the total length in this application, most of which was down the well casing.

Have connected many that are 2 HP three phase and well guy ran 10 AWG down the well casing, for voltage drop reasons.

Old school well guys might only ran 12 to them but many those running them on VFD's are very particular, they won't be covered by warranty if they don't follow instructions and they often request me to run larger supply conductor to the controller than I normally would select.

I think the op’s is residential single dwelling, so unless it’s really deep, most likely 1 horsepower or less.

 

[kwired]

I think the op’s is residential single dwelling, so unless it’s really deep, most likely 1 horsepower or less.

most the new wells I've run power to on new dwellings or even just updated wells for a primarily dwelling use past 10 years seemed to have 2 HP three phase submersible, and a single phase to three phase constant pressure drive.

Back when similar application was using big pressure tank and simple on/off control they depended on the size of pressure tank to handle demand surges as well as to lessen short cycling and were only using anywhere from a 1/2 to 1 HP pump on most of them.

I think to have more success with constant pressure they are going with larger pumps, but can always run at lower speed when demand is low is kind of the concept as they often only have a small expansion tank on them.

 

[hillbilly1]

most the new wells I've run power to on new dwellings or even just updated wells for a primarily dwelling use past 10 years seemed to have 2 HP three phase submersible, and a single phase to three phase constant pressure drive.

Back when similar application was using big pressure tank and simple on/off control they depended on the size of pressure tank to handle demand surges as well as to lessen short cycling and were only using anywhere from a 1/2 to 1 HP pump on most of them.

I think to have more success with constant pressure they are going with larger pumps, but can always run at lower speed when demand is low is kind of the concept as they often only have a small expansion tank on them.

Is this community wells? Overkill if for a single residence, unless they have landscape irrigation. Around here, we seldom have landscape irrigation, but do have a few community wells.

 

[PaulMmn]

most the new wells I've run power to on new dwellings or even just updated wells for a primarily dwelling use past 10 years seemed to have 2 HP three phase submersible, and a single phase to three phase constant pressure drive.

Back when similar application was using big pressure tank and simple on/off control they depended on the size of pressure tank to handle demand surges as well as to lessen short cycling and were only using anywhere from a 1/2 to 1 HP pump on most of them.

I think to have more success with constant pressure they are going with larger pumps, but can always run at lower speed when demand is low is kind of the concept as they often only have a small expansion tank on them.

...also sounds like the pump is constantly running, even with no demand. For a single-family home, a pressure tank allows small demands (one flush and a hand wash) without activating the pump. I agree- constant pressure doesn't sound like a single-family home solution.

 

[qcroanoke]

It needs a controller. Get a well guy involved, unless you want to pay for one on your dime.

And they will pull it to see what it is and the controller it takes to run it.
And if I was gonna do all that I'd drop a new pump and controller anyway.
Especially if it's gonna serve the new cottage.