On Jul 8, 12:42*pm, "Robert Swinney" wrote:
Dan sez:
"The house is mostly wired with 14 gauge wire and 15 amp breakers. *So
the drill press with a 1.5 hp motor will pop the circuit breaker if
used for very long."

AFAIK, there should be no time limit as to how long a given load operates from a CB. *Could it be
your motor is defective and draws excessive current after it warms up? *Figuring 1000 Watts per HP
(Allowing for normal PF and efficiency) a fully loaded 1.5 HP motor on 120 volts should not trip a
15 amp breaker. *The aproximate 12.5 amps is well within the 15 amp rated CB. *It is highly unlikely
the drill press will be fully loaded to 1.5 HP all the time it is on; thus it appears something is
wrong with the motor or the CB is the real culprit.

Bob Swinney


Interesting problem; What is the drill capacity? Do you REALLY need
1.5 HP on it?

These motors are notoriously inefficient, as are most split-phase
motors.

Consider: 1.5 HP x 746 Watts/HP / .67 efficiency = 1670 Watts maximum
demand. (I'm estimating the efficiency based on pool pump motors).
Supply: 115 VAC x 15 Amps = 1725 Watts. Therefore pretty marginal
set-up if the motor is loaded to capacity.

The circuit breakers have probably deteriorated over the years and the
motor efficiency may very well be less than .67... But unless the
motor is faulty or loaded to capacity, the breaker should not trip.
Can you check the running current with a clamp-on meter?

Wolfgang