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Old 10-25-2008, 11:54 PM   #1
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Well pump control box delema


We have an 11 year old submercible pump and motor, and a control box from 1957. I replaced the control box tonight, but noticed it doesnt have a thermal cuttoff switch in the new one. Can I buy one seperately and wire it into the control box ? Can I just put a 10 amp circuit breaker in there ? Or should I just make sure I have the correct amperage circuit breakers in the main power panel for the pump ? The pump has its own breakers in the panel, 2 of them side by side for 220 I guess. The control box said something about 8 or 9 amps, so im thinking something like a 10 amp breaker protection ? Would that mean buy two new 5 amp breakers, or two 10 amp breakers ? Aside from having the pump and motor pulled and replacing the motor with one that has the built in thermal cuttoff switch, what would be my best plan of attack here ? Dennis

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Old 10-26-2008, 11:53 AM   #2
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Well pump control box delema


I would think the new control box without the thermal shut off is better than the one you had. Since the thermal shut off is located in the motor, you should have two wires with no where to put them, right? Are there no terminals marked in the new box for the thermal switch in the motor? P1 & P2? You can put these two wires in series with the pressure switch or contactor if you have one. Submersible pump motors are under water and not subject to overheating in most cases. Overload and short circuit protection are all that is required.

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Old 10-26-2008, 12:40 PM   #3
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Well pump control box delema


The thermal cuttoff switch was a circuit breaker, in the old box, that would kick out if the current drain was too high. I guess it had a bi metal switch in there, hence the term thermal cuttoff switch. Just another circuir breaker. Im told that since the pump and motor are 11 years old, the pump motor probably doesn't have a thermal cuttoff switch in it. Im going to try to get the specs on the motor today, but im not sure we have the model number of motor. I just dont want to take any chances and burn the house down. lol If by chance the motor does have a built in thermal cuttoff switch, an extra circuit breaker in the box won't do any harm. Just some added insurance in case this motor doesn't have one.
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Old 10-26-2008, 12:48 PM   #4
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Well pump control box delema


The motor has 3 wires coming from it, red, black, and yellow. From the main power panel, there are 2 wires, black and white, black is L1, and white is L2. There never was a gnd wire going into the box. It's been working fine since 1989 when we bought the house, but we had to replace the pump and motor in 1997, so thats 11 years ago. The origional pump and motor lasted 51 years ! The pump guy was amazed, and wanted to keep the pump and motor for his collection, as it was the oldest he had ever pulled up.
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Old 10-26-2008, 07:47 PM   #5
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Well pump control box delema


We found the receipt from when the pump was replaced 11 years ago. The pump is a 12 SB 10412, serial number E9728498, but I can't seem to find anything online about it. It would be nice to know if that has the thermal cuttoff switch built in or not. Anyone have a way of finding the specs on that thing ? There are no numbers showing seperate pump and motor, just that one part number. Im lost at this point. Now were lookin at one of those fancy protection boxes that looks for under and over voltages and other abnormalities. Supposed to be the ultimate protection for pump motors. I don't know what else to do... Dennis
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Old 10-26-2008, 10:12 PM   #6
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Well pump control box delema


Generally speaking, 2 wire pump motors have built-in thermal protection, 3 wire ones do not. The protection for 3 wire motors is at the control box.

Does the new control box have 3 terminals for the motor? Is this installation actually working? I've never seen a control box for a 3 wire motor that didn't have thermals built into it. Doesn't mean they're not made, just I've never seen one.

The thermal overloads are usually a small reset button on the bottom of the box. It's sized to a specific motor horsepower. Some control boxes have one, the ones for bigger motors (usually 2HP and up) sometimes have two.

Motors need two types of protection, short circuit (and ground fault), and overload. A circuit breaker will protect it (well, actually, protect the wiring system) in the event of a short circuit or a ground fault, but not for overloads. A more precise device is needed for overload protection. That's what the little reset button on the bottom of the control box is for.

If your control box has a reset button somewhere on it, and it's sized to the motor (HP), then you're protected.

Rob
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Old 10-26-2008, 10:18 PM   #7
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Well pump control box delema


Nope, it just has a relay and capacitor in there, no circuit breaker, no reset button. I was looking at a Pumptec protection box, but it says :
PUMPTEC FEATURES
  • Works with Franklin 4 single-phase 2-wire or 3-wire induction-run submersible motors up to 1 Hp and 1.5 Hp capacitor-run motors.
We have a starting capacitor, but no run capacitor, so I guess that unit won't work with our system.
Yes, the motor has 3 wires, red, black, and yellow.
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Old 10-26-2008, 10:19 PM   #8
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Oh, it says "and 1.5 HP capacitor run motors, so maybe it will work.
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Old 10-26-2008, 10:34 PM   #9
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Interesting.....That's the first 3 wire control box I've ever heard about that doesn't have overloads built into it.

Rob
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Old 10-26-2008, 10:39 PM   #10
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Well pump control box delema


what is the brand of pump? those numbers don't mean a lot to me without a manufacturer.

I see a problem with only one cap as well if your old one had 2 caps.

as to thermal overload; I have had the button type MM speaks of and a breaker specific to the load as well. If it is a cap start/ cap run, there are usually 2 overloads. You need an overload to protect the start winding and a second one to protect the run windings. They draw different loads and the main breaker is too large for this protection. It must be able to handle the total load (both windings)

toss up the name and model # of the control box too. some of this stuff is available on the 'net and we can look it up.
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Old 10-26-2008, 11:07 PM   #11
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Right now the best I can do is tell you the 1 HP control box came from Tractor Supply, and was a bit over $70.00 out the door.
The old box from 1957 had a start capacitor, a start relay, and a thermal cutoff switch (3 terminal).
The new box has a start relay, and a start capacitor only.
Im told, by the owner of Red Bluff Industrial Electric that all the new pumps have the built in thermal cutoff switch in the motors.
He also said that since our pump is 11 years old, it may not have that in there.
That is the only number on the receipt, and there is no mention of the brand name.
The well is still running fine. I drained it today and gave it a precharge of 25 lbs (3 psi below the cut in pressure), oops ! the book said 2 psi.
I think that the Pumptec box is what we need now in order to be fully protected. We also ordered the digital clamp on AC ammeter from Harbor Freight. Its on sale right now for only $9.99 and $6.99 shipping, online.
It has 20, 200, and 1000 amp ranges for AC.
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Old 10-26-2008, 11:21 PM   #12
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Quote:
=freeonthree;177272]Right now the best I can do is tell you the 1 HP control box came from Tractor Supply, and was a bit over $70.00 out the door.
you can't see any name on the thing? Kind of odd.


Quote:
The old box from 1957 had a start capacitor, a start relay, and a thermal cutoff switch (3 terminal).
the old box only had 1 cap? then the only thing different is no overload, right?

.
Quote:
Im told, by the owner of Red Bluff Industrial Electric that all the new pumps have the built in thermal cutoff switch in the motors.
He lied

Quote:
He also said that since our pump is 11 years old, it may not have that in there.
good possibility but they did have thermal overloads way back then too.

Quote:
That is the only number on the receipt, and there is no mention of the brand name.
then I am lost with any info on the pump. Maybe one of the well guys that post will recognize the numbering system as some specific brand.


Quote:
The well is still running fine. I drained it today and gave it a precharge of 25 lbs (3 psi below the cut in pressure), oops ! the book said 2 psi.
I think that the Pumptec box is what we need now in order to be fully protected. We also ordered the digital clamp on AC ammeter from Harbor Freight. Its on sale right now for only $9.99 and $6.99 shipping, online.
It has 20, 200, and 1000 amp ranges for AC.
Sounds like you are good to go except for the overload. With no info on the pump, it would be tough to get a correct ovreload anyway. Once you can meter the load, you might try contacting Franklin to see if you can purchase an overload that would be appropriate.

Not sure what the Pumptech box does. I read a bit about it but it;s late and it was not pertinent at the time. I'll look tomorrow if nobody else has come up with any other answers.
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Old 10-27-2008, 12:02 AM   #13
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Well pump control box delema


Yes, only difference is no thermal cuttoff switch. I just don't have the new box, or the box it came in, in front of me, and I have my leg off already. lol
I think the new pump and motor are goulds and franklin brands. The old box was a Jacuzzi (spelling ?).
I'll try to get the brand name of the new box online now...
maybe our pump has a thermal cutoff. That would ne nice...
How do you do the quote thing ?
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Old 10-27-2008, 12:22 AM   #14
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Well pump control box delema


The new box is a Sure-Dri SD-F305, 1 HP/230 volt, for use with 4" submersible pumps. The pump motor is 11 years old and is a goulds or franklin. Do ya think it might have the thermal cutoff switch built in the motor ?
The new pump was installed 6-11-97.
The box that the new control box came in says Pentek, but the label on the box says Sure-Dri

Last edited by freeonthree; 10-27-2008 at 12:50 AM.
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Old 10-27-2008, 09:42 PM   #15
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Submersible pumps come in two pieces; the pump and the motor. They can be purchased separately, or as a factory assembled unit. Goulds is a respected manufacturer of pumps. They don't make motors. Franklin is a motor manufacturer, specializing in submersible pump motors. Both of these manufacturers have been around for a long, long time.

Franklin motors haven't changed much over the years. The 2 wire ones usually have built-in thermal overloads, the 3 wire ones usually don't. Just because you have 3 wires coming out of the wellhead doesn't mean you have a 3 wire motor. Check for resistance between all of the wires. If one wire is open (infinite resistance), then your motor is 2 wire, and the installer just didn't have any 2 wire cable handy.

To properly size the thermal overloads, we'll need to know the full-load amps of the motor. Of course, we don't have that information, but if we had accurate resistance readings between each of the 3 wire combinations (BLA to RED, BLA to YEL, and RED to YEL), we very likely could determine the HP of the motor, and thus the amps. We'd also need to know the approximate length of the wire (distance from the control box to the well, and depth of the well), and the wire size (gauge). You could also hook it up, turn it on, and measure actual current.

The reality of pump thermal overloads is this; it's just about impossible to overload a centrifugal pump that's properly installed. With centrifugal pumps, the HP needed decreases with rising pressure. About the only way to overload a submersible pump is to have a deep-well pump installed in a shallow well. It is possible however, for the motor to fail to start. This can happen in a number of ways, a bad capacitor or a bad start relay are the most common. Mineral deposits on the shaft and impellers can also lock it up, but it's rare. In this case, the motor sits there and hums until one of 3 things happens.
1) The thermal overload trips (if there is one).
2) The circuit breaker in the electrical panel trips.
3) The motor burns up.

Obviously, #3 is the least desirable, but if it's fed power and doesn't start in about 20 seconds, that's what happens.

The control box you described seems to be a sort of universal replacement. The reason it doesn't have thermal overloads in it is because it is designed for a range of motors, not one specific motor. The old box was designed specifically for the motor it operated, thus the thermal was properly sized.

The risk is up to you, if the old pump never tripped the thermal overloads, the new one likely won't either. On the other hand, article 430 (motors) of the electrical code requires that every motor be protected against overloads and failure to start. A properly sized circuit breaker will protect against failure to start, but a properly sized thermal overload or a set of fuses is needed for overloads. I really don't know how a manufacturer can get away with building a control box without thermal overloads, unless the instructions say that the installer needs to provide separate overload protection.

Rob

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