New to forum with a major submersible pump problem

Users who are viewing this thread

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
Hi everyone, new here first post so a small intro is in order. I am retired, live in a very small and isolated community in SE Alaska and am building a home here to relax and catch halibut and salmon etc etc and did I mention relax? Anyway the wife and I are doing everything ourselves on the house (not a LOT of relaxing, but sometimes satisfying). Back in September a well driller from another town was here doing wells and we had ours drilled. 260 feet and only a half gallon a minute. We already had a cistern set up before when we were hauling our water so kept that tank set up and ran the well straight to the cistern tank without any pressure tank, just a float switch that would fire up the pump when the level would drop 50 gal.

This seemed to work like a dream for the first month or so and then yesterday a fuse blew in the disconnect switch. I replaced the fuse and put an amp probe on the 2 hots and sure enough one was drawing 6 amps and the other a whopping 17.5! The half horse pump still runs and pumps water but I have to keep a 20a fuse on the one leg in order to fill the tank. I know that this is not a good condition. I checked the resistance to the ground wire from the two hots and each were about 2.6Mohms. and the resistance between the leads is about 5.7 ohms which is a little over max (the pump manual says max is 5.2 ohms) but I took this reading at the house which is about 400' from the pump.

So the well driller wont answer his phone and someone says he takes off for Florida in the winter so I am left with the prospect of either hauling water or renting a boom truck and pulling the well pump myself. If I do the latter I really want to know what went wrong in the first place because the whole thing is kind of stressful, especially going into winter.

So here are a few questions for the group. First off is the float switch I was using is one of those with the metal ball inside a rubber float. I was just switching one leg off. Is this okay or should I use a contactor? Another question concerns letting a pump run free of any back pressure save the head pressure in the well. I read somewhere that a pump can draw too much amperage with low pressure such as my setup. This seems counter intuitive to me but perhaps the pump overspeeds without any pressure. Is this the case and could this have toasted my pump? The water level in the well when full is about 43 feet down.

The pump is a 1/2hp McDonald 2 wire. I have what is known as a "Pumptec" hooked to it to shut the pump down for a predetermined time if it runs dry. This and a disconnect with 8 amp fuses as recommended in the manual.

Sorry for the long windedness of this post but felt like giving as much details as I could may be of some help.
Thanks!
Dave
Haines, AK
 

Reach4

Well-Known Member
Messages
38,749
Reaction score
4,400
Points
113
Location
IL
amp probe on the 2 hots and sure enough one was drawing 6 amps and the other a whopping 17.5!
You have a ground fault. The two hots on a 230 V pump should have equal currents.

ground wire from the two hots and each were about 2.6Mohms.
That does not match the other symptom. Either the "ground" wire is not grounded, or the short is between the fuses and where you measured the resistance. How did you isolate the wiring to measure the resistance to ground?

It could also be that the short is intermittent. It could be a short that only arcs over a small gap when the voltage is high.

You should either use a 2-pole contactor or a 2-pole float switch. However that lack is not causing your symptom.
 
Last edited:

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
You have a ground fault. The two hots on a 230 V pump should have equal currents.


That does not match the other symptom. Either the "ground" wire is not grounded, or the short is between the fuses and where you measured the resistance. How did you isolate the wiring to measure the resistance to ground?

It could also be that the short is intermittent.

Yeah, this is where I am confused too. I measured the resistance from each hot to ground right at the well head where I lifted the feed to the house off. I was trying to isolate if the problem was above ground or below. I suppose it is possible the ground wire wasn't hooked up down at the pump but I watched the guy make up the splices and he seemed to have gotten it right.
 

Reach4

Well-Known Member
Messages
38,749
Reaction score
4,400
Points
113
Location
IL
Yeah, this is where I am confused too. I measured the resistance from each hot to ground right at the well head where I lifted the feed to the house off. I was trying to isolate if the problem was above ground or below. I suppose it is possible the ground wire wasn't hooked up down at the pump but I watched the guy make up the splices and he seemed to have gotten it right.

So most likely the fault is between where you lifted the feeds and the fuses.

Disconnect the hots at the fuse box, and measure resistance to ground again. You can measure with respect to a water pipe ground if you like. Actually, maybe you should check for voltage before resistance measurement.
 
Last edited:

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
So most likely the fault is between where you lifted the feeds and the fuses.
Well that would certainly be nice but when I separated the line from the house from the leads to the pump at the well head I energized the disconnect and took an amp reading and got zero on both legs.
Thinking about what if it is intermittent ground fault. What if it only grounds out when the pump is running? Is that possible?
 

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
So most likely the fault is between where you lifted the feeds and the fuses.

Disconnect the hots at the fuse box, and measure resistance to ground again. You can measure with respect to a water pipe ground if you like. Actually, maybe you should check for voltage before resistance measurement.

I will give that a try in the morning. Thanks for your help!
 

Reach4

Well-Known Member
Messages
38,749
Reaction score
4,400
Points
113
Location
IL
You should be able to pull both fuses to do the isolation..
 

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
You should be able to pull both fuses to do the isolation..
Good morning. I went out and took more readings. Isolated both ends of the run from the disconnect to the well head. Resistance reads from well to disconnect were all "O.L" on my meter. Then I tried reading from the motor leads to the well casing which just made the meter dance around. My thought being what if one of the shrink tube over the connection at the pump was leaking water. The thing is the 6" well casing isn't lining the well all the way down, only until it reached solid rock for a ways. So any reading would be traveling through water and rock for a hundred + feet. I don't know, this thing sure has me baffled and I really want to understand where the problem is before rigging up a tripod to pull this thing. This morning I switched on the pump and topped off the cistern, seems to pump fine but still draws the 17.5 amp constant.
 

Reach4

Well-Known Member
Messages
38,749
Reaction score
4,400
Points
113
Location
IL
This morning I switched on the pump and topped off the cistern, seems to pump fine but still draws the 17.5 amp constant.
On a normal 2-wire pump system, the current will be the same magnitude in the two hot leads unless there is some kind of a short.

If you pull one fuse at a time, the current should be zero through the wire that is still powered.
 

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
On a normal 2-wire pump system, the current will be the same magnitude in the two hot leads unless there is some kind of a short.

If you pull one fuse at a time, the current should be zero through the wire that is still powered.
That's a good idea, am going to try that now..
 

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
Just checked amps on the bad leg with the fuse pulled on the good side. Drew around 12.5 amps. This may suggest the nick in the wire somewhere and nothing to do with the pump.
 

Arktikos

New Member
Messages
8
Reaction score
0
Points
1
Location
Haines, Alaska
Okay on further examination I found the ground fault! It is right under the well head cap. Now we have a nice even 6 amps on each leg!
Thanks so much Reach4 for your help in finding this issue and saving me from pulling the pump. My brain just wasn't getting a handle on this one..
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks