Pump stopped working (getting 120V instead of 240V?)

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
A couple of days ago my pump suddenly stopped during operation. I first checked that the breaker wasn't tripped, then turned the timer switch on and off a few times but the pump motor didn't respond, no sound at all. I took the motor off and had a pool shop examine it, and they said it works fine. Then I followed this to test the voltage at the timer switch box, and found that terminal 1 has 120V, but terminal 3 is measured only 3V compared to ground. I measured the input wires, so it shouldn't be the connection screw's problem. I'm out of idea of what to do next. Any suggestions? Thanks in advance. (Edit: my pump is Century SQ1152 that runs on 230V)
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,280
Bedford, TX
FS,

Sounds to me like you have lost either the L1 or L2 leg of your 240 volts.. Keep in mind that you can't measure L1 to ground plus L2 to ground with the pump installed..

I'd start at the main pool circuit breaker in your house panel and test between L1 and L2 and see if you have 240 or not. If not, the circuit breaker is bad or popped. If you have 240 there then move to the next item in the line.. Not sure of that is another circuit breaker at the equipment pad or a timer.. Either way the test is the same..

Based upon not having 240 between pin 1 (L2) and pin 3 (L2) which are the input wires to the timer, either a wires is open or more likely whatever is feeding the timer is bad.. I assume this would be a breaker..

Thanks,

Jim R.
 

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
So here's the layout and test results today.

The house's main panel is mounted on the north wall outside. Two black wires supply power to the pump. Label them as L1 (lower) and L2 (upper). From the main panel, there's a conduit go to underground, that contains 5 wires: L1, L2, a blue wire, a white wire, and a green wire.

The pump, motor and timer switch are located on the south side of the house, roughly 100 ft away from the main panel. The underground conduit comes straight up to the timer switch box. Three wires comes from the conduit: 2 blacks (should be L1 and L2), and 1 green. Inside the timer switch, there're 4 places to connect, labelled as T1, T2, T3, and T4. The green wire connects to ground. The two black wires connect to T1 and T3 respectively. When the timer is turned ON, T1 is connected to T2, and T3 is connected to T4. T2 and T4 then power the motor.

Voltage Tests:

Flip the break on the main panel to ON, L1-L2 has 240V, but T1-T3 has only 120V. Then turn timer switch ON, T2-T4 also only got 120V to the motor. But the motor needs 230V.

Continuity Tests: with the help of two extension cords, I tested the following:

T1-L1 ~0 (good)
T3-L2 240K (open wire?)

My multimeter displays "0.L" when the two points being tested are not connected. Here T3-L2 didn't show 0.L but ~240 kilohms. I also tested the other two combinations: T1-L2 ~270K and T3-L1 ~160K. Not sure how to interpret these numbers. I thought they should be 0.L as well.

I also did the following, which is even more confusing:

L1-L2: if I put red pin of the multimeter on L1, black pin on L2, I got ~ 4 megaohms, but when I switched the pins, it measured a couple hundreds kilohms.

T2-T4: 0.L (good, as expected)
T1-T3: ~5 kilohms (big surprise to me. Is this a problem? if so, probably in the timer switch)

My questions are: (1) Does this mean that one of the wires, T3-L2, is open and I need to replace it? (2) If so, how difficult is the task? I'm totally new to this, want to fix it by myself which is probably faster and cheaper, but also don't want to mess it up in the process, (3) do other measurement numbers make sense? especially the 5kilohms between T1-T3.

Not sure if this kind of electrical questions belong to this forum or not. I just want to get my pump running sooner and guys here seem extremely knowledgeable and helpful. Let me know if I should take the questions somewhere else. Thanks!
 
  • Like
Reactions: Jimrahbe

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,280
Bedford, TX
Flip the break on the main panel to ON, L1-L2 has 240V, but T1-T3 has only 120V.
FS,

If between T1 and T3 at the timer, you do not have 240 volts, one of the black wires is open.

Let's look at the fact that 5 wires are going into the conduct and only 3 are coming out... That means that along the way somewhere there has to be a junction box.. It could be right below the timer inside an outlet box?? I have no idea where it is, but it can't be underground it has to be visible and accessible. While the wire could just be open in the middle of the conduit, it is most likely at some junction point.

Your task now it to find that junction box.. Even if the wire is bad, you still need to find and open the junction box.

Thanks,

Jim R.
 

Brett S

Well-known member
Mar 15, 2019
643
Orlando
Flip the break on the main panel to ON, L1-L2 has 240V, but T1-T3 has only 120V. Then turn timer switch ON, T2-T4 also only got 120V to the motor. But the motor needs 230V.
I’m very confused about this. L1 to L2 should have 240V, so that’s good. But without something being miswired, T1-T3 can’t have 120V. Either it would have 240V if everything was working, or it would have 0V if there was a bad wire. The only way for it to have 120V would be if T1 or T3 was connected to neutral or ground. But if that was the case then the pump never would have had 240V.
 

Brett S

Well-known member
Mar 15, 2019
643
Orlando
I’m very confused about this. L1 to L2 should have 240V, so that’s good. But without something being miswired, T1-T3 can’t have 120V. Either it would have 240V if everything was working, or it would have 0V if there was a bad wire. The only way for it to have 120V would be if T1 or T3 was connected to neutral or ground. But if that was the case then the pump never would have had 240V.
Unless maybe if the timer was on and the pump was still connected, then you could potentially get a weird reading between T1 and T3. I would say disconnect those wires from the timer and then test them and see if you get 240V or 0V across them.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,280
Bedford, TX
Brett,

I am just "assuming" that when the OP did not get 240 between T1 and T3 he measured to ground..

Thanks,

Jim R.
 

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
Jim, you're probably right about a junction box. There's a light fixture in the pool and I suspect the blue and white wires went there through a junction box. I'll check it tomorrow.
 
  • Like
Reactions: Jimrahbe

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
Brett, these tests were done without the pump in the loop. I took the motor off and haven't put it back. Tomorrow I'll test it again with wires disconnected from the timer. Thanks.
 
  • Like
Reactions: Jimrahbe

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
Indeed there's a junction box about 20 ft away from the timer switch. Five wires (2 blacks, 1 blue, 1 white, 1 green) come into the junction box, the blue and white are used for 2 GFCI outlets and 1 light switch, then go to an underground conduit. The other 3 wires (2 blacks and 1 green) come into the junction box then go out through another underground conduit. Inside the box these 3 wires used twist-on connectors. When the main panel breaker is ON, the 2 black wires get 240V, so the connection from main panel to this box should be good. The problem seems to be one of the black wires between timer and the box, and I was able to identify which one by testing continuity. I tried to pull the bad wire a little bit, from either end (the box and the timer switch), but it felt stuck. I don't know how to replace this wire.

I re-tested the voltage between T1 and T3 while both are disconnected from the timer. It does register 120V. Also when I measure the resistance between the two ends of the bad wire, I didn't get 0.L (total disconnect) but a few hundreds kilohm, even though both ends are disconnected from everything else. It seems that somehow the wire has gone bad but not totally disconnected, kind of wired to me, but I have no other explanation.
 

Brett S

Well-known member
Mar 15, 2019
643
Orlando
The only way you could get 120V between T1 and T3 would be if one of the wires was still live and the other was connected to neutral or ground. I guess if the conduit is metal then it’s possible that it failed in such a way that it’s touching the metal conduit, which of course would be grounded.

As far as replacing the wires go, I would probably plan to replace all of three of the wires between the junction box and the timer. If one failed then who knows how close the other ones are to failing as well. You certainly should be able to just pull them out (and pulling all three out at once will probably be easier than just trying to pull one out since they could be twisted together at some points). When you are pushing new wire through the conduit I would strongly suggest that you get some wire pulling lubricant as it will make it much easier to put the wires through.
 

Jcciaschi

Member
May 31, 2020
12
Richmond, VA
As an electrician, it sounds like you have found the problem and need to remove the wire. I highly, highly suggest you replace all 3 wires as the other member had suggested. If one wire is damaged it is very likely that it caused damage to the other wires or whatever damaged to the first wire also caused damage to the other wires. When pulling wire it doesn't matter which side you pull from so pick the side that has more room. Also, tie a string to one of the wires BEFORE you remove them. This way when you need to install the new wires you will have a string in there to tie the wire to and redo the pull.

Another thing to try is to remove the wire nuts on the black wires and make sure those connections are clean and the wire is good. I have seen wire corrode when placed in outside boxes due to moisture. You are supposed to use wire nuts that are rated for outdoor use (they have a gel in them to prevent water/moisture from contacting the wires), but they rarely get used in the real world.

If you really need to get the pump running you could connect the ground wire in the junction box and use it as the other line wire to the timer. Its not the best solution but it might get the pump running while you work on a solution to replace the wires. Just remember to remove the ground from the timer box and put it as L1 or L2 (whatever the bad black wire is you are removing).
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,280
Bedford, TX
FS,

I concur.. Replace all three wires at the same time.

The only possible way for you to read 120 VAC between the two black wires going to T1 and T3, is that one wire is open... And at the open, the side that goes to the timer has shorted to ground.. Almost unheard of.. Wow... Great troubleshooting!!! :thumleft:

Thanks,

Jim R.
 

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
Brett, Jcc and Jim, thanks for all the advices! You guys just gave me the confidence that I need to carry this out. I'm going to use the ground wire idea to verify that the bad black wire indeed is the culprit, then proceed to replace all 3 wires. It may take me a day or two to find time to do these.

As for my pool, I've been using a submersible pump to keep the water circulating and maintain FC level. So far the water has been clear, but the floor has some stuff since no filtration. As a new TFPer, I see the importance of maintaining FC level.

Thanks!
 
  • Like
Reactions: Jimrahbe

FS2019

Member
Jul 21, 2020
14
Tucson, AZ
This morning I confirmed that if in the middle box the incoming black wire is connected to the outgoing green wire, at the timer I can get 240V between T1 and green wire! Plan to buy wires, pull strings, and lubricant late afternoon from home depot, and try the wire replacement before dinner or tomorrow morning.
 
  • Like
Reactions: Jimrahbe

Jcciaschi

Member
May 31, 2020
12
Richmond, VA
If you are buying wire before removing the old wires, save yourself the hastle and use the old wires to pull the new wires instead of pulling a string. To do this take the green wire and about 3" bend it back on itself to create a loop in the wire. Then take the new green wire, feed it through the loop and bend it back over itself. Then use electrical tape and wrap it around both sides tightly. This causes the wires to hook each other. If you not sure what I just explained look up pulling wire in YouTube and you should find something. Repeat this step with the other wires BUT make sure the loops are offset from each other. If all 3 loops line up it will be too big to pull through the pipe. Once all three loops are connected you can try pulling all 3. If that doesn't work try pulling 1 at a time. Make sure to buy more wire than needed, it sucks doing a pull and coming up short - had that happen before. Good luck!