# Pool Pumps... - NON Theatre...



## koncept (Jul 10, 2006)

Well, this summer I am working at a pool, this past Saturday our pump stoped working, its amp rating is 19-21 on 220 -240v. Since last year we had been having problems with the breakers so I figured this issue was the breaker just finaly giving up and saying that i don't want to work anymore. So after an hour of arguing with my management company I convinced them to send an electrician out to check it out, I am not permitted due to liability reasons. so after the electrician came we found out that the pump was using two single pole 20 amp breakers with a little piece of metal to bind them together to make a double pole. the electrician said the breaker was undersized because of startup surges so he put in a 30 amp double pole (its not a gfci/rcd breaker...). after that the pump still did not start so he came to the conclusion that the pump is burned out....it was replaced two to three years ago. so now they still have me working at a pool that no one can swim in currently....

so that was my interesting weekend.


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## Radman (Jul 10, 2006)

I bet management's real happy you got their pool shut down, lol.


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## koncept (Jul 10, 2006)

oh they just love me....lol. well to top it off i think the cause is because of the two single pole breakers and one of them tripping off keeping one leg of power going to the motor....i was trying to get that fixed last year.....but as we can see it didnt get done till two days ago


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## mbenonis (Jul 11, 2006)

You know, when I first saw the thread title, I imagined someone trying to use pool pumps on stage somehow (despite it saying "Non Theatre")....

Even though a lot of people aren't going to be able to swim for a while, you did the right thing. All it takes is for a failed pool pump to make the water hot and you have a huge problem on your hands. Better safe than sorry.


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## koncept (Jul 11, 2006)

it gets better they came out and replaced the pump today, after it ran for an half hour it shut off without tripping the breaker. on a side note they still have #12 wires with a 30 amp breaker. so i called and they came out, they threw a clamp on amp meter on there one leg read 12 while the other read 18 (side question, can someone tell me what the total amp draw there is, bc im pretty sure you dont add them up) so they said leave it off and we'll get someone else out here tommarow...so we are still down... they are trying to figure out why it got hot enough to trip the thermal protection circuits in the pump... (im open for others thoughts)

mbenonis: what do you mean make the water hot??? im slightly confused by that last line


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## audioslavematt (Jul 11, 2006)

koncept said:


> mbenonis: what do you mean make the water hot??? im slightly confused by that last line



Hot = current flowing through it


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## koncept (Jul 11, 2006)

umm ya....that might get to be a problem should htat ever happen.... I wish the people on swim team understood the need for gfci's/rcd's. when they ahve meets they have this electric trigger to signal people to jump in and well its 3 feet from the pool... 2 prong extension cords...hmmm i see a problem but they just dont seem to get that one...


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## MHSTech (Jul 12, 2006)

koncept said:


> they are trying to figure out why it got hot enough to trip the thermal protection circuits in the pump... (im open for others thoughts)


 Is there still water flow to the pump? I don't think those things are really designed to run dry. But it sounds like you have some serious electrical problems or a streak of bad pumps. 

By the way, this is a recirculation pump, right? It sucks that you've been out this long, because you're still going to be out the rest of the day, even if the pump gets fixed in the morning, by the time you shock the pool and clean it. And for those of you that aren't "in the know", when I say shock, I mean to increase the pH to somewhere way above 7.5. This cleans up all the cloudyness and corrosion in the pool that you start getting with a pH level of 7.4. But when you shock it, you don't let people in it because it can cause irritation.


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## ship (Jul 12, 2006)

a 12ga wire at times is sufficient for temporary loading in up to 25 or 30 amps. Since you won't find many 25amp breakers, a 30amp is normally used. In the case of wiring and start up amperages veses running amperages of a motor, it's possible that the 12ga wire was rated for it's use. Possible in theorizing but not placing any stamp on it. Voltage drop by way of undersized conductors can also tend to burn up a motor/pump but so can running a pump dry or in overload.

Innitially and from what I read at least electrically I would not surmise anything wrong with what I read. Yep, probably I would go with both the bridge - breaker lever attached breaker and internally linked breaker for this application, but as long as bridged by way of bolt and or bridging mechanism there is nothing wrong by way of the NEC of having a bridged breaker lever tied set of circuit breakers.

I'm thinking that the problems expressed so far are more complex than those expressed so far with the system.

ON the other hand, Kudos to you for getting the electrician out.


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## koncept (Jul 12, 2006)

when the second pump blew, the water flow meter was reading about 190 - 200 gpm (i think its gpm). we should be able to open in an hour from the time the pump gets going. all we still need to do is vaccum, it been shocked several times since going down (just following thier instructions). i think you got shocking wrong, shocking is where you increase the clorine lever to higher than normal (like a 5 - 7 range). depending upon what you use to shock the pool, you may need to increase your ph as some of them do lower it.

i would agree that 12ga is too low. i think i remember seeing a label on the pump that use #8 for bonding (im not sure what that means though, if you feel like explaining ship that would be great)

i had a chance to look at the old 20 amps that were left here, and one of them appears to be shot, if you flick it a couple times you can feel the swich go loose where it doesnt trip anything when you move it. somehow this small pump problem seems to be far more complex than any of the electrical work i had ever done...

Personaly i wanted to get one of my friends (they are an electrician) out there so that i would know all the details...


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## Chris15 (Jul 12, 2006)

koncept said:


> use #8 for bonding (im not sure what that means though, if you feel like explaining ship that would be great)



Now I'm not Ship, but I believe that bonding would be the wire the joins the casing of the pump to an earth / ground connection of the electrical system, so a thicker gauge of wire would better allow any fault current to pass to earth.


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## jwl868 (Jul 12, 2006)

This is a different tack, but the issue could be a poor motor selection for the pump. The short answer is that the pump will attempt to draw whatever power that the piping system allows it to. If this draw is greater than the motor’s output, it will burn out the motor. 


The long answer: The pool’s recirculation pump is probably a centrifugal pump which will operate only under specific set of flow and corresponding system pressure (head) conditions. These conditions are graphed as flow rate vs head to generate the pump’s “pump curve”. The flow rate and pressure drop (calculated by analysis of the system) determine the “operating point” on the curve. The power required to move the water through the system and operate the pump can be readily calculated from the flow rate, head, and pump efficiency, the latter of which varies with the flow rate and head. After one calculates the required horsepower, the horsepower is rounded up to the nearest standard motor size.

Usually, pump vendors include lines of constant horsepower superimposed on the pump curve to aid in the selection of the motor size. More often than not, one motor horsepower will be entirely above the pump curve, and one or two lower horsepower motors will intersect the pump curve such that part of the motor line is above the pump curve and part is below. 

The necessary condition is that the motor horsepower be above the operating point on the pump curve so that the motor is not overloaded, and this is where a problem can occur. Usually, the person buying the pump will specify that the motor size must of a size such that the motor is never overloaded regardless of the operating point on the curve (this minimizes the impacts operating errors and other system failures). However, there are cases where the pump buyer will look at the operating point and see that a smaller (and less expensive) motor will work. And this may be fine provided that there in no way for the pump to operate at conditions elsewhere on the pump curve, at the high flow – low head end of the pump curve. And this can be caused by having the flow throttled too little, operating in a bypass line with no flow control, operating at too high of a flow rate, or replacing the pump impeller with an impeller that is larger than the original (creating a bigger pump curve outside the motor range).

Joe


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## koncept (Jul 12, 2006)

well its a 5hp pump and its back up. they changed out the double pole 30 amp back to the two 20 amp singles...so lets see what happens.... i guess in the end i dont care, its not my problem, all i do is guard and try to know a little about what happens.


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