ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Questioning the electrical norms
by gfretwell - 03/03/21 06:05 PM
Lock-down Thread
by gfretwell - 03/03/21 12:38 PM
Northern Tool Recalls Powerhorse Generators
by Admin - 02/25/21 09:49 PM
You will never guess
by gfretwell - 02/25/21 07:48 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 13 guests, and 18 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
well pump motor check out?? #172905 12/29/07 03:55 PM
Joined: Oct 2002
Posts: 830
sparkync Offline OP
Anyone know what I should look for when checking out a submersible well pump. Can I just ohm it out, or will I get a reading through the windings. I'm talking about at the top of the well without pulling the pump out. Checking it at the pressure switch. I checked one out from each wire to ground and had no shorts to ground. Is there a certain ohm reading I should look for between the wires. This pump only has two wires feeding it. Thanks, Steve..

Work Gear for Electricians and the Trades
Re: well pump motor check out?? [Re: sparkync] #172907 12/29/07 04:41 PM
Joined: Nov 2007
Posts: 763
KJay Offline
I usually test for ampere draw at the wires at the well cap. Most of the 2-wire, 3/4 HP submersible pumps around here draw about 9 to11 Amps at 220 to 240V.
There is usually a tag or decal on or near the well cap with pump motor specs. Sometimes it’s at the circuit panel or at the controller if there is one.
Some brands of two-wire pumps also use a controller. If it has one I would check out the capacitor in it. Sometimes they go bad.
If you have the correct voltage at the well head then the pump is going to have to be pulled.

Are you going to pull the pump yourself?

If it’s less than 100 feet and connected with black plastic CPVC pipe, it shouldn’t be to hard to raise it. If it’s deeper or hard piped, you will need some help to raise and dissemble the pipe sections and then for reassembly

Re: well pump motor check out?? [Re: KJay] #172909 12/29/07 04:48 PM
Joined: Jul 2002
Posts: 8,379
Trumpy Offline
I'd put a Megger on it between each of the cores you have and ground to make sure the windings haven't gone down to ground inside the pump housing.
What's actually wrong with this pump?
If the pump does need to come up, expect to get wet and slimy with the slime that sticks to the pipe and cable.
Yuck, I hate pulling them up.
BTW, how old is this pump?

Re: well pump motor check out?? [Re: Trumpy] #172911 12/29/07 05:14 PM
Joined: Nov 2000
Posts: 2,148
resqcapt19 Offline
You might find some help here.

Re: well pump motor check out?? [Re: resqcapt19] #172913 12/29/07 06:57 PM
Joined: Oct 2002
Posts: 830
sparkync Offline OP
Thanks for the replies. The problem with the pump was that it would start ok, pulling around 9 to 11 amps on start up, then leveling off at around 6 or 7 amps. It would run for about 1 minute or so then the amp reading would go down to
nothing. Then the homeowner would turn on more water and the pump would come on again, with the same amp readings, then it would trip the breaker. I checked all the connections, changed the breaker, and ohmed the wires going down to the pump, where I would get a reading between the two hot legs but not to ground. I realize that I could have been getting the reading through the windings, but with the motor acting the way it was, it looks to me like the motor IS bad. And No I'm not pulling it up. Going to let someone else do that. That's a little beyond my job description smile I was just wanting to know the next time I run into this how to definitly determine that the motor is bad so I can tell the customer something for sure. Thanks for the link Don. I'll check it out. Thanks for all the replies. Steve..

Re: well pump motor check out?? [Re: sparkync] #172915 12/29/07 07:20 PM
Joined: Oct 2002
Posts: 830
sparkync Offline OP
Just called the homeowner. He said the well man came out and determined that the wire coming from the house to the pump, must have had a knick in it, and was shorting out. (We just had a whole day of hard rain here) They stretched a new wire on the ground between the pump and panel and he said it's been working fine. He's going to get the electrician that wired it initially to come out and pull another wire. Since the circuit didn't have a "dead short", it didn't dawn on me it could be the wire:( I guess one leg must have been almost broke into or knicked, but not enough to keep it from coming on, then the constant load made the breaker trip. Never too old to learn. Thanks..

Re: well pump motor check out?? [Re: sparkync] #172936 12/30/07 12:53 PM
Joined: Jun 2007
Posts: 301
JValdes Offline
Most of the time we start thinking this, that, and what. Sometimes we make our jobs more difficult than they are. I learned long ago to look for the most obvious and attack from that spot. I can remember jobs that I scratched my head and hands raw just to find a little minor problem. In my experience we just dive into troubleshooting with out a good plan. I am as guilty as everyone else is. But you learn after many years in this business that time is money.

Just think about what happened. The well man found your problem. He knows nothing about electrical, so he runs another wire on the ground and verifies that it was the cable or wiring. You see where I am going. Make it simple. We all should learn from this, and the ones who have learned this in the past can refresh their memories. Keep it simple and don't make it out to be a big problem until you know that it is......I feel better now......John

Re: well pump motor check out?? [Re: JValdes] #172938 12/30/07 01:19 PM
Joined: Mar 2004
Posts: 947
twh Offline
I don't think that you can reliably test a motor or wiring without a megger. Often, a fault to ground won't register on an ohmmeter.

Always test the wiring separately from the motor. It is embarrassing to have equipment down while the motor is being replaced and again while the wiring is being replaced, or vice versa. Or, even worse, to replace one when the other is the problem.

Re: well pump motor check out?? [Re: JValdes] #172939 12/30/07 02:21 PM
Joined: Jul 2007
Posts: 1,335
sparkyinak Offline
That may have been a tough one to find without all the rain. Rather even a megger would have found it in a dry condition or not, I do not know. I had a similar situation few years back. We upgraded a fire alarm system and once in a while, it would get a ground fault for a while and then disappeared. We chased it for weeks. Many times by the time we get there and the fault would be gone. If it was still there while we were there, it would go away while we were working on it so we had no idea if what we did had anything to do with it or not. It was fustrating for all involved to include the person who worked next to the panel.

I eventually speculated the one of existing exterior horn strobes were the culpret. We live in middle of a rain forest. Everything here is wet. Once I convinced everyone that had to be the problem, We replaced them and the problem went away. Sometimes it is the weather plays a factor in finding the problem. I have similar experiences with underground wiring. If the problem is connected to the outside, I ask about the weather. You may get dumb looks but it lead you to the source of the problem...

"Live Awesome!" - Kevin Carosa


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
lil suzi
lil suzi
Posts: 57
Joined: August 2003
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
275,603 Are you busy
209,528 Re: Forum
196,892 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3