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Electric Motors/Leeson Motor Wiring.

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Question
I just bought a used lathe with a Leeson 3/4 hp motor (Model C6C17FB2B).  It is running 115v, but I want to switch it to 220v.  The wiring is currently L1 to T1,T3, T8 and L2 to T2, T4, T5.  The green wire going into the terminal housing has been clipped so it is apparently not grounded. How do I reconnect the wires for 220v?  Where does the green wire connect?  There does not seem to be a terminal for it.  ( There are 2 holes on the motor casing at the back of the terminal housing, but they do not appear to be tapped.) Does it just go on one of the bolts on the end of the motor?  Thanks for your help.

Answer
Dee,

First look for a hidden connection diagram either on the data plate lower corners, or inside the connection box,   these are often hidden,    but it is a standard NEMA connection.

Very important     green wiring should be EARTH GROUND<   you need to prove the feed green is earth ground,  just because it is green, some people have no idea and use the green as a power lead,     you need a properly sized, and continual connection from the supply to the motor frame,   

All the way,  the earth ground wire is what helps bring any short circuit current up fast and trip the breaker  [starter or overload or both or all]

Breakers are horrible protection for motors,  too slow,     if you want a really good protection,  install a fused disconnect   so the fuses are the primary trip,   not expensive, and much much faster,  if a problem develops.


Right now your motor is wired in PARALLEL     

Now you want to go to 220 and need an external series connection,    it will be like this:

Line to T1 and line to T4,   220 volts to those two motor leads.

That leaves you T 3,8,2, and 5.

T 2 and T 3 are electrically connected and isolated, [taped off].

That leaves you T5 and T8,  these are start winding leads. and determine rotation.

Depending on the rotation you want, put T5 with either T1 or T4, if correct rotation, fine, if not, swap T5 and T8   so you will have either T1 and T5 to line,  or T1 and T8 to your high voltage line.  Whatever goes on T1, be it 5 or 8,  the other goes on T4  once you verify the rotation,    I like to check for myself,    probably because you had T1 and T3 and T8,  you will now have T1 and T8 to line,     BUT CHECK IT FOR the rotation you want.

Its a simple swap of T5 and T8 for rotational change.

There should be some sort of ground screw in the junction box, but it really makes no difference,  if the screw is missing,   just put the green proven earth ground wire to a clean and tight frame connection of the body of the motor.

Not sure why they cut it off,    but YOU WANT IT AND NEED IT,    all the way to the source,  frame/earth ground is what it is,   

I know this gets confusing, with like appliances, where it used to be the neutral was used for ground,   three wire 220     now the new electrical code calls for a four wire connection,  the older three wire in existence is grandfathered, but if a new appliance is installed,  now the three wire feed must be changed to a four wire,    

But do not confuse appliances with motors,  motors only care about the voltage to the T Leads,  the ground is not part of the feed circuit   protection for overload  or shorts  is what it does,       but prove the green feed line is to earth,    once confirmed  follow and connect to the body of the motor, now you have a correct ground.

If you need further explanation,  write me at my Shop MEAR Services Inc,  in Kansas City Missouri,    repair@mearservice.com,  or write to my personal email   make the subject something that mentions allexperts follow up,   so I know,   or you can reply back through all experts, whatever is easier for you.

My personal is wbwill@sbcglobal.net,     but you should have no problems,  and it is a good idea what you are doing,     NOW SOME will tell you the 220 uses less power    NOT TRUE<   remember,    power is power,  lower the voltage, the higher the current     higher voltage lower the current,  but in the OVERALL,   the formula is  voltage times amps,     

So say at 220 volts the amps are 10,  and at 110 volts the amperage is 20,   but when you multiply either   220 by 10    or 110 by 20    same figure,    

The reason it is a good idea, is the higher voltage needs less wire size, saving on wiring and starter size costs,     just like a power company does, it sends out way high voltage then transforms down,    at substations,   then further down as needed by individual transformers.

But at 220 volts you need half the size of wire feeding the motor and in a long run can be a big savings,      but it is not like most think    lower power use,   it takes X power to run a 3/4 HP motor,    period,     also in a residential situation, it is easier at the higher voltage to size the breaker, because you don't need the higher current rated breaker,     

So no power savings, the cost savings is in the materials needed,   wire, breakers so on,   

Let me know if you have any problems  and I will help you get to where you want to go,

Will Babbitt

Electric Motors

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Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site

Experience

30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.

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EASA, IBEW [retired], other specialty organizations, Lubrication, Vibration EDI, Tribo-electric Councils

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Currently fielding concerns at this site under "Home Electrical"

Education/Credentials
4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.

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