Ice storm in NC yesterday, power out for who knows how long, running on our standby generator.

Some back ground information:

5000W gasoline generator - 2 120V sockets (standard), 2 240V sockets (standard, 1 hot prong 90 deg. to the other) - neither are twist-to-lock. When running, generator is grounded by low gauge heavy wire to nearby separate 10' ground rod.

Deep well water pump - 250' deep, 220V pump motor

When the power is out for days (like it will be now...), we typically run the well once per day for an hour or two, do all our 'water tasks' for the day then. Rest of the time its the furnace or a window A/C, lights, refrig, etc. - I run on extension cords, so I unplug all of those before setting up for water. I made up a cord for the generator & well water pump years ago just from Romex with a 220V standard plug on one end (2 hots and a ground), and I direct-wire it to the infeed/line side terminals at the pressure switch (disconnecting and isolating of course the feed from the panel). From that point, the pressure switch cycles the pump motor on/off as needed to keep the pressure tank filled.

I have probably needed to do this 3 times in the past 10 years. The first two times, everything worked fine - before, during, and after the use of the generator.

The last time I tried, a year or so ago, I hooked everything up as usual, but the water pump wouldn't start. It didn't make sense, thought maybe I had connected something wrong at the pressure switch, went to get my meter to see if I was getting 120+V from the generator at each leg at/after the pressure switch, when the power came back on. Pressure switch and pump motor have worked fine since then on line power.

This morning I hooked everything back up again to try to run the pump - nothing. I have 133+/-V at each 220 leg at the generator socket (hot-to-ground), and I have 133+/-V at the LOAD side of the pressure switch - so there are no breaks in the Romex or plug, and the pressure switch is pulled in connecting to the pump....

But the pump won't start, same as last time.... Yet this exact same setup has worked fine, as expected, in the past.

I'm stumped - am I missing something? Thanks in advance for ANY help or suggestions you have.

 

Welcome to the forums.

That sounds like a 120vac 20A recepatacle.

Disregard any measurements from one leg to ground or neutral. You need to see +/- 240VAC across your two hot legs.

With your 133v measurement.... it sounds like you are missing one hot leg.

 

First of all, stop measuring from leg to ground (or neutral). Your pump is a 240 volt load so you need to measure leg-to-leg and look for reading between 230 and 250 volts. Next is to either measure that voltage when the pump is attempting to start OR using an ammeter measure the current when the pump is trying to start. If the voltage sags significantly OR the current is higher than the generator can supply then you are probably SOL.

There are several different reasons why the pump may have started in the past but won't start now. One trick that might work is to close off the discharge valve on the pump and then open it very slightly and then try to start the pump. If it then starts immediately open the valve wide.

Post back if you have more questions.

 

Thanks, folks, I do appreciate the help.

The generator sockets in question, with the 90 degree to-the-other prongs, are labeled 240 and measuring Volts above that, and have run the 220V well pump before so I am certain they are not 120V.

Hot-to-hot/leg-to-leg is measuring 270V right now, both at the generator and at the load side of the pressure switch when it should be 'trying to start', so I don't think there is any voltage sag. The 120V outlets on the generator are measuring 135V - these both sound high, I know it varies a little bit with RPM, but earlier today the 120V side was measuring 122V, without a load but is now 135V without a load...

I wish I had a clamp-on ammeter, but I want to add that when I plug in the water pump plug to the 240V socket, the engine RPM does not change at all, like there is 0 load. When I plug in a 120V cord, I get the typical slight bog down in RPM from the load (furnace fan, refrigerator, whatever) and then smoothing back out to the correct RPM. From the water pump plug-in, nothing - like it isn't even trying to start. In the past when the generator did start the pump, we would get a pretty good sag in RPM and then smooth recovery when starting, from the amperage load spike at startup I assume. I haven't tried the discharge valve partial close thing yet - shouldn't there be some sign of trying to start?

At 5000W, the generator is rated at 20.8 Amps for 240V, and the breakers in the panel are both 20 Amp - could it be that this generator is no longer producing enough 'surge' amperage to start the motor? If so, shouldn't it be "trying" as evidenced by some indication of a load when first plugging in to the socket?

 

Yet the pump runs fine when connected to utility power? That IS a stumper. How do you effect the transfer of power between the utility and the generator?

To make certain we are using the same terms when you write "load side" you DO mean the side of the pressure switch connected to the pump and not the electrical source, correct?

If there is no perceptible change in the noise of the generator and no change in the voltage at the load side of the pressure switch when the pump should be starting then there is no need to check the amperage and no need to try starting with the discharge vale closed, the pump is NOT receiving power for some unknown reason. Does this pump also have a "control box" or is it directly from the pressure switch to the pump down the well?

I have one more thought but it is a long shot and if it works it denotes a serious problem with either the pump motor or the wiring. Do you have a "ground" connection on the generator? Do you know if the generator's neutral connection is bonded to the generator's ground connection?

 

Just to reiterate.....


You need to measure 240VAC on terminals 1 and 3 and on terminals 2 and 4.

 

ThankYouThankYouThankYou again, folks, I appreciate you sticking with me on this.

PJmax, yes - I have measured the voltage between 1&3, and 2&4 from your photo, and they are both 270V+/-, the same as at the generator panel for the 240 socket.

Furd - yes, the pump WAS running fine when the utility power went out - and this same situation happened about a year ago - power out, hooked up as normal, pump wouldn't run, started to troubleshoot, power came back on, pump ran fine once utility power was restored, never did any further troubleshooting.... Ooops.

I disconnect utility power from the pump by physically removing the Romex from the panel/Line side from the pressure switch, replacing it with the generator cord I made. So at that point there is NO physical connection with the utility - not line, not common, not ground (at least ground through the panel).

Yes - "LOAD side" means the side of the pressure switch connected to the pump.

No panel or box after the pressure switch that I am aware of - just Romex underground to the well head (large diameter concrete pipe on end in the yard) and down the pipe to the pump. I've had that well head cover off before, no junction or control boxes in there.

I DO have a ground connection on the generator - a tab at the end of the actual generator body. I have a separate (in addition to the house main panel ground rod) 10' ground rod sunk in my yard, and I connect my generator ground tab to that ground rod with about 15' of 8 gauge stranded wire when I run it. I have NO idea if my generator's neutral connection is bonded to the generator's ground connection. Someplace I can look or check? Have NOT (recently) run the generator without grounding it to that rod, but I HAVE in the past when I couldn't find the ground rod clamp.

This well pump is the ONLY 220V item I ever run from the generator, so I have no base of experience for if other 220V items won't run either.

Willing to try/check/research anything...

 

If you measure that high of a voltage actually going out to the pump.... then it should run.
Unless the pump has some kind of internal overvoltage protection and your generator voltage is too high.

 

You can test for a bonded neutral by connecting your meter from one side of the 240 volt receptacle and the other meter lead to the grounding terminal of the generator. Repeat with the other side of the 240 volt receptacle. Both should read one-half the voltage when measuring from one side to the other of the 240 volt receptacle if you have a bonded neutral. If you get any other readings, if the readings are not the same or you get no reading then the generator does NOT have a bonded neutral.

When you write Romex I assume that you mean type NM cable. I hope by all that is holy that you do NOT have type NM cable running underground, even if it is in conduit as type NM is NOT listed for use in damp or wet locations and a buried location, even in conduit IS a wet location. Type UF cable would be acceptable up to the well head but for the down cable you really need to use submersible pump cable.
Is there any kind of pump control box BEFORE the pressure switch?

Why do you connect the generator's grounding terminal to this lone stake? What purpose does it fulfill? Do you know WHY utility systems have a ground? (I suspect the answer to that last question is no but I have to ask.)

One more thing, are you using a digital voltmeter? If so, change the batteries. Most digital voltmeters will not give a proper reading if the batteries are low.

 

I have a feeling you have a bad capacitor or diode and you're reading some kind of false voltage.

Can't explain it but, I had a Briggs and Stratton stand by generator I worked on for a customer. The generator output voltage was 250 but, nothing would work

Went to check capacitors, and one had the top blown off.

Replaced both capacitors and walla, output 250 volts but, everything worked.

 

Can you get to the well head and make a connection directly to the pump from there assuming you are getting 240 v from the generator this would eliminate any cable problem,
Or use your ohmmeter to check for an open in the cable between the controller and the well head.