You are here:

Electric Motors/Dewalt 1600s radial arm saw


Hi, this might seem a silly question, but anyway here it is:

On my DeWalt radial arm saw, model 1600s (one of the heavy green ones, made in Italy) and on the motor plate it says 220v/380v 3-phase, with two differing wiring diagrams - one for 220v and one for 380v. Also on the arm is a sticker, saying 'motor connected at 380v'

Could it really be as simple as changing some connections to make this run as a single phase saw? Obviously the plug would need to be changed, but would I also have to change some cables, say the one from the motor to a junction box/the one from junction box to plug?

Many thanks in advance if you can help,



Not a silly question at all,   none are,  

Here is the deal,     Three phase is three phase,    in the US and Countries that abide by NEMA type conventions, dual voltage  [which HAS NOTHING TO WITH THE number of phases the motor was designed to operate on] is twice the low or half the high.

Like these examples,    220/440    230/460     110/220    in the first two examples,   they are essentially the same,   as more and more electrical demand comes in to play,  the utilities in order to provide MORE POWER    we use KW -Killowatts  K being a thousand,    one KW  1000 watts,   that IS POWER        

The reason our voltage grid is spread across the country side at tremendously high voltage is because POWER is both VOLTAGE and CURRENT,        Raise the voltage  lessen the current to do the same job or supply the same amount of POWER,      look at any device single or three phase,  if the voltage is high say  440  and the current built into the design, the current rating is say   20 amps,    if you want to power that same device on HALF that voltage the current is 40 amps,       

So as above the power grid is designed to use very high voltage   because it takes smaller wire,   then transformed down to safe and useable power,      if the utilities did not transfer power over great distances at very high voltages  100s of thousands of volts,   the wire size needed would grow in many cases in a linear fashion   and instead of one inch cable delivering megawatts of power,    at lower voltages we would need  8 inch cable    very expensive hard to maintain,   so on a lower scale,   what used to be "normal"  in and around residential substations,   and to individual transformers was adequate at 220,   now to deliver more power    

they have inched up the power  preventing the need for larger cables, and infrastructure,   

Now most devices have tolerances, say 10% fairly common,  so the 440 volt device or the 220 device  will operate on 230  or 460       it is like adding a penny to a gallon of gas,  dont seem like much  until you pump BILLIONS OF PENNIES worth of gas,  and now you have some serious money,   same kind of thing    a gradual yet useable method of delivering power without upsetting the entire apple cart,    

What you have is a NEC or European convention where the voltage ratings are not double the low and half the high      basically series and parallel        

The NEC type of convention uses a wye and delta voltage scheme,  where high is wye   star   those terms,   and low is Delta     not quite parallel  and not half or double but around a 58% difference,     

US conventions use nine leads three phase to get low and high,    NEC uses six leads,  to get low and high       but low and high   when you use wye for high,  and delta for low   gives you these high ratings at 380 volt     wye connected,    and     then   delta for low   which is 220 volts,    

Most people associate 220 with residential voltages,  it looks familiar,  and it suggests single phase    but it simply a coincidence,        again three phase is three phase,     voltage makes no difference,    

I have seen 2300 volt single phase,    and 20 volt three phase,       phases are phases    voltages can be exactly the same value,  but a three phase 220 volt device needs three leads for three phases,      a single phase 220 volt device needs two wires both hot  voltage between the two hot leads   is 220 volts,          same thing for three phase   phase a to b measured  220 volts,   b to c  220 volts,   c back to a 220 volts,         

all LINE TO LINE VOLTAGES,   three phase takes three leads  single phase takes 2  but the 220  familiarity is confusing,  and often mistaken as single phase    just because it says 220

You have a three phase saw,    it will run on 220 volts but three phase  line to line to line  or 380  line to line to line,       low connected delta,  high connected wye,     

So what to do with your three phase saw  and you only have single phase,    

a rotary convertor,   one that stays on line  not one that provides a short term fabricated third leg that drops out and the motor runs on single phase but very very wrong and very very unbalanced,        so a constant on rotary type convertor will work  if you match the kw of the convertor to the kw of the saw,  or the HP  but kw is a better measurement of POWER    

OR you go find a single to three phase variable frequency drive,   most frequency drives were developed to control speed    of three phase,      and you could get maybe a 1/2 HP rated drive that would take single phase and convert it to three phase,    

Now you can buy drives that go up to 5 HP and still have the ability to convert from single to three phase,      google or search     VFD Drives  single to three phase,          and you will find a ton of different models  some with enclosures some chassis mount,   all with user adjustable parameters including braking, reversing,  ramp up, ramp down,  torque, overload protection,  and often 30 to 50 different internal programmable settings,      

I would advocate you seek out a VFD drive that is rated to handle whatever HP your saw is rated for,  and look to see if it is rated 50/60 cycle  which means it will operate on both but the lower frequency of 50 will have a lower overall speed at 50 than 60  but with a variable drive, you can boost it to 80 cycles if were some device safe to run at that speed,  but all you want is something to get you three phase         

again a rotary converter will do it,  but there are a ton of these misleading "convertors" that only use capacitors to build a short term third leg   then drop out and you are running your single phase saw on single phase   but again  it is bad on the motor   weak performance  and stay away from those,       

The VFD with single to three phase input to output it static,  small footprint, and again many have motor overload protection   come in a NEMA one enclosure  include the other 40 or so adjustable parameters and are very stable,    

But no  just because it says 220  a common single phase voltage    it is STILL A THREE PHASE MACHINE and needs three phase at the designated voltages   on the data plate to operate correctly    

Again search   VFD  single to three phase  and you will find a million choices of brands     look for a familiar brand like Marathon,  Toshiba,  some other decent brands V TECH,  but a little research and one search term    as I mentioned should get you on the path to make some choices,      if you get confused or have questions about one you pick or want to understand in more detail   send me the info and I will help you with it,       

Either a convertor or buy a single phase motor    same frame same shaft size mounting bolts  so the retrofit is not a nightmare,  but I would vote for a VFD   SINGLE TO THREE PHASE CONVERTOR OVER A SINGLE PHASE MOTOR    WHICH ARE COMPLICATE, NOT EFFICIENT AND NO OPTIONS,    


Electric Motors

All Answers

Answers by Expert:

Ask Experts




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


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.

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

Currently fielding concerns at this site under "Home Electrical"

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

©2017 All rights reserved.