I understand basic electricity: running wires, connecting plugs, and putting
tongue on a 120V will give you more than the tingle you get from 9 volts.
I don't understand what difference 240V will make on my table saw and other
I'm in the process of running 240V into my shop and was wondering if I
take advantage of the feature on my table saw and band saw motors that
them to accept 240V. They run 120V now.
Can someone tell me what running these at 240V would do for me? Will they
be more powerful (i.e. not bog down easily?), improve startup time, or just
run up my electric bill?
THere is one main advantage to 240 over 120, and that is delivering
twice the power before tripping a circuit breaker. Basically, most
household circuits will have a 20amp breaker and appropriate gauge wire
to match (the thicker the wire, the higher the breaker amperage that
you can safely install). Power is proportional to the voltage times
the amerpage. Hence, a 1.5HP contractor saw may suck up around 15 amps
at 120v running at full duty, but only 7.5 amps when running at full
duty on 240v.
Now, imagine that you have a table saw and a 1HP dust collector (let's
say around 10amps at 110v) running at the same time on the same
circuit. Put in a piece of 2" thick oak and push it har through your
saw and the lights will go out as your circuit heats up from the 25
amps on the line. (Remember to shut of the table saw before switching
the breaker back on unless you have a magnetic switch!) If you
converted both to run on the same 240v circuit, this would not have
happened as the draw would have been only 12.5 amps.
Running the tools from 240V reduces the current draw by a factor of two. You
won't change, since the with twice the voltage and half the current the
power is the same.
Basic advantage of 240V operation is that voltage losses in the wiring are
reduced because of
the reduced current consumption. This can provide slightly better motor
performance in the
range you are talking about, and usually better starting (when current draw
One other effect you may notice is less flickering of other lighting in the
house. Heavy current
draw on 120V slightly unbalances the transformer+wiring, and the light
output of an incandescent light
is pretty sensitive to voltage.
Typically larger tools that draw a lot of amps will be straining when the
going sets tough and typically this is the time that you do not want a motor
to stall or slow down because of voltage drop caused by the inability of the
electrical feed not being able to supply the proper amperage. Typically
with 240 volt the amp draw is 1/2 that of a 120 volt tool. Voltage drop is
is typically no longer a problem and the motor does not lack for power.
I do not believe that you will see any more power other that when under a
load. Again since you will probably not be having a voltage drop the motor
continues to run more efficiently when under a load. Start up time may very
well be more abrupt, again little or no voltage drop during the amperage
sucking start up period.
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