Shop Wiring: 110v vs. 220v
M
ANY WOODWORKERS ARE CONFUSEDabout when to run
110v and when to run 220v wiring in the shop. First, let’s dis-
pel the myth about operating motors on various voltages: An electric
motor operating on 110/115v will use the same amount of power (to
do the same amount of work) as it does on 220/230v. (A few defini-
tions will help here: A watt is a measure of electrical power; a volt
denotes potential differences that cause the current to flow; and an
ampere is a measure of the amount of current flowing through a
wire.) The myth that the motor will use less power on the higher
voltage comes from the fact that it uses half as many amperes (amps)
on the higher voltage. But what you buy from your utility is watts, not
amps. The number of watts equals the number of amps times the
number of volts. Thus, when the amps are half but the volts are dou-
ble, the watts will be the same.
The advantage of using 230v for heavier machinery is that you can
run slightly smaller wires to the machines because the full-load amps
will be one-half of the 115v value. Because of the lower amp load, the
line voltage drop at the machine under heavy cutting conditions will
be less. With more stable voltage, the motor will develop higher torque
than it would under sagging or low-voltage conditions, which can
occur if the motor is operated at the lower voltage.
In general, motors up through 1 hp can be operated quite success-
fully on 115v. Operating on 115v gives greater portability because this
voltage is commonly available in any shop or job site. Machines with
2-hp and larger motors will operate better on 230v. Motors with
11 ⁄ 2 hp can operate successfully at either 115v or 230v.
—EDWARDCOWERN,Wallingford, Conn.,
from a question by Al Coppola, Mulvane, Kan.
SHOP SETUP