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22K views 36 replies 5 participants last post by  J. V. 
#1 ·
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
 
#2 ·
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.
 
#3 ·
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.
 
#4 ·
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.
 
#5 ·
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
 
#6 ·
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
 
#7 ·
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.
 
#10 ·
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.
 
#11 ·
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.
 
#12 ·
=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.


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?

.
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

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.

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.


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.
 
#13 ·
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 ?
 
#14 · (Edited)
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
 
#15 ·
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
 
#16 ·
Yep, after I installed the box I saw where it read that the motor must have a thermal cutoff switch built in. Thinking back 11 years ago, im kinda remembering the guy saying something about being double protected now, while talking about the old box, and said since the old box was working fine, he saw no reason to replace it. I will take the resistance readings, and post the results. The relay and cap are in the cover, and connect thru heavy slide in terminals, so I shouldn't have to remove any wires to take the readings. If what you say is true about 3 wire motors not having thermal cutoff switches, then why would the box have terminals for 3 wire motors and say the TCO must be in the motor ? Hmmmm.....
 
#17 ·
The thermal in your motor works just like the type used in a hair dryer. Overheats, opens the motor winding within the motor. Just connect the motor as described in the control box diagram.

What readings do you plan to take? If you do not have a winding diagram for the motor, you are wasting your time. The breaker in the panel will protect the circuit and the thermal in the motor will protect the motor.
 
#18 ·
I see you didn't read the post before my last one. Our pump and motor were replaced in 1997, 11 years ago, so it may not have a thermal cutoff switch in it.

Micro Mind said"
"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."

You see, we don't know whats down there. The guy didn't write down any useable info. The part number on the receipt won't come up online, and the dude is retired now. The well is running fine now, but were afraid that we don't have any protection other than the power panel. The old control box was origional from 1957, and had a thermal cutoff switch in it. Thats what was tripping, and shutting the pump down, so I replaced the whole box, then discoved that there was no thermal cutoff switch in it.

The owner of Red Bluff Industrial Electric (not a pump business, but he does alot of electrical and motor work) told me that he thought it was like 7 or 8 years ago when they started putting the TCO switches in the pump motors. If I only had a valid motor number to look up. All I have is a receipt from 1997 that says it is pump number 12 SB 10412 and that it was $484.00 before tax. I hope that clarifies things for you... Dennis
 
#19 ·
Dennis, Sorry I did not look back at your previous post. Bad habit of mine. At least it is running and not an emergency. I would continue to work with Rob (micromind) for peace of mind. No pun intended.

I will add this. If this were my pump system I would leave it alone for now and get another new pump motor and cable. Then replace it at your next convenience. 11 years for a submersible pump is better than would be expected. This statement would be viable to me (IF) it were my only source of water.
 
#20 ·
Hmmm... I was told by the guy who installed the pump, that average pump life was about 20 years. Our old pump was from 1957, 40 years old ! The pump guy was shocked and wanted to keep it for his collection, and said it was the oldest set he had ever pulled up. lol
 
#22 · (Edited)
I'd like to see 20 years, it's been 11 so far. Our well is 240 feet deep. When the pump was replaced 11 years ago, the bill was like $1600.00. Makes we want to weld up an A frame, add a winch to it, make or buy the pipe securing clamp, buy a couple of hefty pipe wrenches, and handle everything except casing issues myself. If by chance the casing ever needed replacing, it would be cheaper if the pump was already removed also. I watched the guys pull and install the pump, it was not hard work at all with the right setup, just a bit time consuming pulling 12 20 foot sections of pipe. Dennis
 
#25 · (Edited)
I forgot that Micromind wanted to know the wire size and length, so I opened the box again. The solid copper wire measures .080in and im guessing 40 feet from well to box, tank and pressure switch, so thats 280 feet of wire roughly. While I had the box open, I noticed all the female spade connectors were just crimped on, so I soldered them all. Dennis
 
#26 ·
The results of about 20 minutes of research:

1) The diameter of #14 bare wire is 0.064". #12 is 0.081". #10 is 0.102". Your wire is #12. The resistance of #12 is 1.93 ohms per 1000'. Your run is about 560' (280' out, and 280' back.) The resistance at the motor will be 1.08 ohms less than the reading at the control box.

2) The resistance of the main (run) winding is actually about 2.1 ohms. The actual resistance of the start winding is about 10 ohms.

3) The Franklin book shows the resistance of a 3/4HP 3 wire motor to be 3.0-3.6 ohms on the main winding, and 11.0-13.6 on the start. A 1HP model is 2.2-2.7, and 9.9-12.1 A 1-1/2 is 1.7-2.2, and 8.0-9.7 These figures assume a 30C (86F) temperature. Since this motor is in a well, it'll be colder. Resistance decreases with temperature.

4) This is most likely a 1HP motor. The model number is probably 21450889003S. If this is the case, the book lists this motor as having built-in thermal protection. The full-load amps is 8.2 The service factor amps is 9.8 Most submersible pumps load the motors into the service factor, I'd expect the actual current to be about 9 to 9.5 This current will appear on the yellow and black, the red should read pretty close to 0, as it's only in the circuit during starting.

Rob

P.S. This research was fun!!
 
#27 · (Edited)
Wow ! Thanks Rob ! That was some fancy calculating. I looked in the manual, at a list of motors, but it didn't get that close. That number must be a complete pump and motor assembly, and the book only shows motors. Closest I got in the book was a 2145081.
I really appreciate your assistsance with this. I need to study that info, and play with the calculator now and try to understand how to do this on my own the next time. I can't thank you enough Rob. I have the harbor freight meter coming, and it will be both fun and educational for me to check the current draw on the yellow and black motor wires. Do I need to check starting current also, or is the run current enough ? Dennis
 
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