600 yard to pump

[AC\DC]

Client has a very old system it’s goes under state road through another owners property.
Pump is 600 yards from well house.

I did not know how far it was when I put a 2-pole gfci in. But the reason I did it was because it was a two wire pump with no ground .
The gfci held for about a year .
The gfci I put in is finnaly tripping so pump or line is broken, or gfci is getting more sensitive either way it has to be fixed.

They’re going to bore that far but a 2hp motor at 240 volt draws 12 amp.
With a 3% vd I am looking at 4/0
If I boost it to 480 with Tran and back down still looking at 1/0
( aluminum for both)

Poco is not an option to get down there..

Have not felt with boring before.
Seems I use there conduits and I don’t supply any. I just size it for them.

Getting a transformer to boost it up seemed good at first but the wire size does not go down that much plus paying for waisted heat.
Any ideas would be appreciated

 

[__dan]

I believe you would need a Right of Way to cross or use the other properties for any reason. If you have a Right of Way you could consider crossing them with utilities. If there's no Right of Way, it's possible that would preclude any improvements.

You would want to know that first. It could be that the original circuit was just put in with a friendly nod, and those days are gone now.

I don't know but I am wondering how fussy a drive would be if the incoming Voltage was off from the load Voltage. Either working as a voltage booster for the low line side or as a Voltage reducer, say feeding the drive a boosted higher input voltage but telling the drive to output for the pump nameplate.

I see the pump is single phase so that would include a new 3 phase pump.

For me the easy first step would be is to answer those two questions. Do you have a right of Way to consider new work, and a call to a drive manufacturer about trying something off spec (possibly boosted higher input single phase voltage to get the nameplate output 3 phase Voltage). I am thinking it's possible if the drive manufacturer can OK it.

A drive if any would have to be out at the pump.

Just saw the two wire pump with no ground. I don't know but my opinion would be the GFI is not safe for a no equipment ground circuit. If it's not safe, it would be a shock death hazard. New feeder or off grid solar.

 

[winnie]

Your voltage drop calculations are off.

At 1800 feet, 240V, Al conductors, 3% allowed drop, 12A current, you are looking at 2/0AWG.

At 1800 feet, 480V, Al conductors, 3% drop, 6A current (double voltage means half current) you are looking at 4AWG.

Remember that a motor is a rotating transformer. You can boost the voltage at one end and then use a higher voltage motor at the other end, saving one transformer and its losses.

I know VFDs are used for well pump control, but I don't have any experience to make suggestions. In theory you can have a voltage doubling drive that would take 240V single phase and create 480V three phase to run the pump. A 2 Hp 3 phase 460V motor only requires 3.4A, getting you down to 10ga copper for acceptable voltage drop. A VFD also takes care of the issue of voltage drop during starting. Like I said 'in theory', if you go down the VFD route you want someone experienced with such systems.

-Jon

 

[AC\DC]

They have an easement

 

[AC\DC]

Winnie you are right I rounded up to 2000 and put in 15 instead of 12. Was looking for a quick estimate. But I was far off cause that’s a good drop in wire size.
I personally have never delt with a vfd.
What manufacturer should I call.

Just read your last paragraph about should not attemp without experience seems best bet then is a transformer to a new 480 volt suppressible pump

 

[__dan]

If I did not know who to call and started random dialing I would call Danfoss first. Their VLT drive is bulletproof.

Next would be ABB. In the old days ABB was easy to get on the phone and get answers. They had great toll free support. That's really the issue today, who will answer the phone and give free engineering support with a phone call.

I know the guys like Yaksawa. I see a lot of Yaksawa's when something blows up and they swap in someone else's drive. Never had to call them myself.

 

[winnie]

I just did a search for 'VFD well pump' and turned up several suppliers.

For example:

Should I Put My Pump On a Variable Frequency System? — Oakville Pump Service

Learn the various advantages and disadvantages of a constant pressure system, also called a constant pressure pump system. To know more about VFD and constant pressure controllers, contact Oakville Pump Service at (707) 944-2471.

oakvillepump.com

Variable Frequency Drives, Variable Frequency Drives For Well Pumps

Watson Well variable frequency drives for well pumps save you money by varying motor speeds to match your water demands.

watsonwell.com

But I wouldn't do this for a customer without some experience, eg you might better serve your customer by contracting this out.

 

[James L]

With a 3% vd I am looking at 4/0

Why are you looking at 3% voltage drop?

If you start with 245 volts, which is common around here, you could go with #2 aluminum and still be above 230 volts at the pump with 5% drop

Even if you actually start with 240 volts you'd still have 228 volts at the pump with #2 AL

 

[Mr. Serious]

OP didn't say what the actual voltage was at the house, but on a rural system it could be somewhat unpredictable, or just run low all the time. I wouldn't want to size the wire for 5% drop and then find out the incoming voltage at the service is only 220 volts. Regardless of what the incoming voltage is, the customer will pay for more energy input with more voltage drop.

 

[winnie]

Also of concern for motors is starting current. If you have 5% voltage drop under normal load you might see 25% voltage drop under starting conditions.

-Jon

 

[James L]

OP didn't say what the actual voltage was at the house, but on a rural system it could be somewhat unpredictable, or just run low all the time. I wouldn't want to size the wire for 5% drop and then find out the incoming voltage at the service is only 220 volts. Regardless of what the incoming voltage is, the customer will pay for more energy input with more voltage drop.

It's true that voltage could be squirrely.
My point is to start with actual voltages and forget about a percentage.

And losing a few pennies for voltage drop will be negligible compared with the hundreds (dare I say thousands) of extra upfront dollars to install larger pipe and wire.

If they lost 10% of their power due to voltage drop, it would probably take 10 or even 20 years to equal the up-front cost he's proposing

 

[hillbilly1]

I think I would meg the feed, could be the pump or wires down the well going bad, not the feed. Usually a splice that sits in water above the pump, it could very well be failing.

 

[Mr. Serious]

losing a few pennies for voltage drop will be negligible compared with the hundreds (dare I say thousands) of extra upfront dollars to install larger pipe and wire.

I thought the payback was shorter than that. I was going to do the calculation, but it's irrelevant if you size the wires bigger for starting current as Jon (winnie) was saying.

 

[AC\DC]

I think I would meg the feed, could be the pump or wires down the well going bad, not the feed. Usually a splice that sits in water above the pump, it could very well be failing.

it’s either being fixed or I am not touching.
2-wire 240 volt pump no egc.
Not safe.

 

[AC\DC]

Thank you all for your input.keep them coming lol

 

[ptonsparky]

Meg the underground and the pump motor. Repair or replace as needed

Put the GFCI at the pump end is better than a poke in the eye with a sharp stick.

Single to three phase VFDs are common enough. Not that difficult.

Get a well guy to do that end of you need to.

 

[hillbilly1]

it’s either being fixed or I am not touching.
2-wire 240 volt pump no egc.
Not safe.

That was very common up till the 80’s. Not necessarily unsafe. Is the piping galvanized, or non-metallic? If the fault is on the pump end, you can still use the ground fault protection if that end is fixed. You will probably find no ground tan down to the pump, only three hots if a three wire, and two hots if a two wire pump. They didn’t start running grounds down to the pumps until the late 80’s.

 

[James L]

I thought the payback was shorter than that. I was going to do the calculation, but it's irrelevant if you size the wires bigger for starting current as Jon (winnie) was saying.

Just the wire price would differ by more than $4,000 upfront $1.70/ft 4/0 versus $.60/ft #2 x 1800ft (times 2 conductors + ground)

Bigger conduit and fittings, bigger miscellaneous items, and more labor might add $6,500 to go 4/0 over #2

12 amps is 3kw x 24 x 365 = 26,280 kwh if it runs round the clock

At (roughly) 20¢ per kwh that's $5,256.00 to run it a full year with 4/0

If they lost 10% to voltage drop, it would add $525 per year to run it with #2

That would take 12 years to pay back

 

[winnie]

@James L makes a good point about calculating the actual cost of energy loss in the wires.

My point about voltage drop during starting is about performance. If you have too much voltage drop then you can have issues with starting up the pump.

-Jon

 

[James L]

My point about voltage drop during starting is about performance

Yes, very valid point, too.

I'm just trying give a perspective from one angle so he's able eat the meat, spit out the bones, and make his best decision.

Hopefully every angle gets solid pushback because there's several good ways to skin this cat