2-wire vs 3-wire pumps

Discussion in 'Pumps and Tanks Well Forum & Blog' started by abikerboy, Aug 23, 2007.

  1. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    From an ITT motor manual loaned to me by an educated professional! Im a dummy, so this is all from the manual only!!!

    3-wire prose and cons
    Pro-Capacitor start assures starts under severe circumstances, such as an excessively deep well, or excessice static head. More torque is provided at the motor for hard to start situations
    Capacitor run assures smoother running, lower current and lower running temp
    All starting components are located above ground, and though the potential for failure is greater, the components can be easily and cheaply accessed and repaired or replaced
    General electrical consumption can be lower, or greater, depending on depth of well and distance from pump to controller
    Cable requires an extra supply lead, but the cable can be lighter in guage
    Cons-capacitors can and do fail as time weakens the internal construction of these devices
    Relay is not sealed from atmospheric pressure, hence contacts can oxidize from repeated arcing
    Cable requires an extra supply lead, and though the cable can be lighter in guage, the weight is 1/4 to 1/3 more, and the added expense can be much greater
    Under residential useage and average installations, starting current consumption may actually be higher due to required setbacks and distance of control box from well

    2-wire pros and cons
    pros-Starting components are all located within the hermatically sealed stator housing of the motor
    Installation is much simpler
    No potential start relay to fail or complicate day to day operation
    No capacitors are used except in some limited designs, and where used, sealed components provide extra protection so the potential for failure of these components may be reduced greatly or may not exist alltogether
    Internal starting switch is sealed from any contact with oxygen so arcing from normal use will not cause contacts to oxidize and fail
    Internal starting switch and lack of one way capacitors can provide pulsed starting torque to prevent motor jambing due to sand mud or other restrictions
    Cable is simpler, lighter, and economical to purchase and to instal
    Motor starts softer, decreasing shock loading of pump components
    ConsIf starting components fail (highly unlikely) motor must be pulled and replaced
    Requires a better eye and closer tolerance for resistance measurements
    Lower starting torque under severe static head. this is the reason that higher horsepower pumps are currently 3 wire
    Operating temp of motor is slightly higher but this should not apply except under abusive circumstances

    *The severe conditions as stated above very rarely apply to the normal residential homeowner. The preference of 2 wire or 3 wire motors is usually a matter of taste for aplications below 1.5 hp. and a 2 wire is always recommended for these installations due to simplicity, cost advantages, and obvious maintenance reduction and extended life of starting components. Refer back to the pioneer days of the electronic semiconductor as all major devices were embrasing the new technological advances of the solid state semiconductor. Time only can prove the advantages of the new over the old.
    Last edited: Aug 23, 2007
  2. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Very good explaination! I suppose it's copyrighted or I could use it in my FAQ's.

    bob...
  3. Rancher

    Rancher Guest

    Why would this be a con for a two wire pump?

    Rancher
  4. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Because potential relays do go bad and when they do that, the start cap is the next thing to go, then the start winding if it persists. With the two wire motor, there is no relay to go bad.

    bob...
  5. Rancher

    Rancher Guest

    So on a 2-wire pump, not having a potential start relay is a good thing.

    Why is it listed under the "con" heading.

    Rancher
  6. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    This is what I read under the cons and I see what you mean. It should be under pros. The guy needs a proofreader.
  7. Gary Slusser

    Gary Slusser That's all folks!

    Which proves (to me that my and Speedpump's claim) that for residential applications, 2 wire pump motors are better than 3 wire...
  8. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Yup, every time. Three wires are just a waste of time and money for residential apps.
  9. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    Its there because Im very bad at details like this early in the morning. Lol! My mistake, and I'll fix it...
  10. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    Yes, I assume it is copyrighted, but this is not worded exactly as it was in the manual...my attempt at being careful. Not sure how or if copyright would apply now, but if it's safe or legal now that it is in my words, then you're welcome to it!
  11. Everything I've either worked on or installed in my area has been 3 wire.

    I'd prefer the simpler the better on these systems but I don't exactly afford a great deal of time into the knowledge base of these since they are a dying breed in my community.

    Troubleshooting these with the customer mindset of "I only got X amount of money to get this back up and running" is not my forte of work regimen.


    Here, call this guy....
  12. Raucina

    Raucina Previous member

    Messages:
    515
    Having just pulled a 2 wire 1.5 hp motor from 800 feet, that would not start after having sat for several years, and then getting it to turn on the surface with just a nudge from a pair of pliers makes me a permanent 3 wire pump setter. Just a few more ounces of shock might have made this a NO PULL job.

    Better yet for our wallets and enviroment, we should be wiring with 480 volt 3 phase, then we can run 18 gauge wire down several hundred feet. This country and its 120 volts is a comedy, probably staged by the copper mills.
  13. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    Judging by what Ive seen in the short time that Ive been passing my labor off to a professional friend, if a pump sits idle in a well underwater for several years, doesnt matter if its a 2 wire or 3 wire, its going to turn into a "pull" situation anyway. You might have had more starting torque from a 3 wire, and maybe it wouldve started in the well, but my added mechanical experience of many years tells me that when any type of bearing or bushing siezes from corrosion due to non use, just write it off as a loss anyway! Even if you were able to break it free with a pair of pliers, and maybe with no effort at all, somewhere within the motor, pump, or maybe both, there is a bushing and shaft with a rough surface. Now that you have it broken free, you have a rough pitted and corroded surface crossing another rough surface at 3450rpm....cant imagine that lasting very long! At least with the pump not starting, you knew what to expect from a well that has sit idle for years...depending on your situation, you could consider yourself blessed that the pump didnt start...as if it did, my bet is that something somewhere within will disintegrate within a short time frame, and probably just when you need the water the very most. As for the 3 phase 460v, I can agree to a very short point, however beyond that, Ive seen what the average guy can do with 120v or 240v when he attemps something that he shouldnt...god forbid 460v to a homeowner! We'd have half of the country burned down by now! Plus, it wouldnt be any easier on our wallets either...heavier circuit boxes, and even though the wire guages may be smaller, you'd have more linear feet of wiring, plus the electric would cost us much more due to the extra equipment that the power company would have to install in places where as of now only single phase circuits exist.
    Last edited: Aug 24, 2007
  14. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Amen.

    With the 460 thing, three phase power is not forgiving to motors that try to start on single phase power because of a dropped leg. Without the very best of protection, three phase is inferior to single phase when it comes longevity.

    bob...
  15. Gary Slusser

    Gary Slusser That's all folks!

    LOL It takes more wire to run heavier gauge 3 phase and more transformers to each house than single phase DA, so where would the savings be? Or do you think just buildings with wells would get 3 phase? Plus, single phase serves most rural areas where the well pumps are BUT, most electrical distribution and service drop lines are not copper.... and haven't been for like 40-60 years.
  16. Raucina

    Raucina Previous member

    Messages:
    515
    You should stick to water treatment. You are way outside your box trying to comment on 3 phase distribution systems. Study up, Buy a book before any more foolish rants.
  17. Raucina

    Raucina Previous member

    Messages:
    515
    As to several years for a motor underwater , I agree the thing should have been pulled. My comment was strictly about starting torque in 3 wire motors, where an extra ounce can be a mile.

    As to electricity, all of industry relies on high voltage and 3 phases to make our machines work, and not many factories burn up because of it. The NET reduction in copper use and efficiency gains are great.

    Almost all of the rest of the world uses 240v house wiring, and there are no issues of electrocution above Americas.

    Most house wiring has a ratiing of 600 volts, so pushing power through it at 120 volts is like plumbing your house with pressure washer hose.
  18. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    I agree again to a point...however in factories, not many average joes are allowed to touch the electrical systems. Try telling the average joe who just bought his brand new "old" fixer upper house that he is not allowed to touch his own wiring....we see right here on this very board every sigle day how well that would work! I agree that the efficiency gains would be great on 460v 3 phase, as far as actual electrical consumtion is concerned, but as for copper useage, that would actually go way up! This was taught to us in basic electrical classes, and also think about the fact that 3 phase has an extra leg, so to speak, which would require extra wiring to feed the device, plus that little single phase motor in your washing machine would have an extra winding of copper inside, plus a magnetic starter on it, and a single light dip of shellac insulation on those windings wouldnt cut it for 460v useage, (Ive seen the inside of an underinsulated 3 phase motor, and Ive seen one go up in flames over an inbalanced electric feed as well) and as a result, that washer would cost you quite more than what it does now. I also hate to think about what electricity would cost us if the power company had to feed an extra leg to each pole, and then turn around and hang 3 phase transformers inside of every suburbia type neighborhood in the country.
    Last edited: Aug 24, 2007
  19. Gary Slusser

    Gary Slusser That's all folks!

    OK, let's see... In another life I worked as a laborer and then line crew ground hand and then went to lineman's school and worked as a lineman in the construction department of a very large power company. I've worked on two conductor 230k three phase down to 6900 volt single phase distribution lines and many service drops to all types of residential and commercial buildings. I prewired many transformers and hung them too. I took down many miles of series wired street lights that had been installed up to 40 years previously and they were replaced with single phase to a transformer and service.

    I did all that in the mid '60s. The series wired street lights was the only copper wire I saw, except for the old copper services we replaced and pole ground wires used on the smallest poles for service drops up to class 9 poles used for three phase distribution of up to 230k, all the way to the meter base and then into the panels; it was all aluminum - not copper.

    So what is your experience with electrical power company distribution (and service drop) lines?
  20. abikerboy

    abikerboy DIY Senior Member

    Messages:
    202
    Location:
    VA
    Not sure about the heavier guage...always open to learning, BUT arent most drop lines aluminum now days? Not just speaking of the actual drop to the meter pan either, but also of the supply line from the meter pan to the service panel as well. May not save any copper by going 3 phase (would probably use more because of extra windings within the transformers and motors of this country), but if Im right, then the aluminum would be what costs us $2 per lb now if we had 3 phase!
    Last edited: Aug 25, 2007

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