North Star M165951C Starting Electric Motors, Extension Cords, 120V, 60 Hz Motors Starting Amps

Operation Instructions

4. Starting Electric Motors

Electric motors require much more current

(amps) to start than to run. Some motors,
particularly low cost split-phase motors, are
very hard to start and require 5 to 7 times more
	120V, 60 Hz Motors			Starting Amps
current to start than to run. Capacitor motors
	HP Motor	Running	RI Type		Cap Type	SP Type
are easier to start and usually require 2 to 4		Watts
times as much current to start than to run.	1/6	525	7-11		9-18	16-22
Repulsion Induction motors are the easiest to	¼	700	9-15		12-23	22-32
start and require 1.5 to 2.5 times as much to	1/3	875	11-18		14-29	26-35
start than to run.	½	1175	15-25		20-40	NA
Most fractional motors take about the same	1	1925	24-40		32-64	NA
amount of current to run whether they are of	1 ½	2400	30-50		40-80	NA
Repulsion-Induction (RI), Capacitor (Cap), or	2	1900	36-60		48-96	NA
Split-Phase (SP) type. The chart shows the	3	4075	51-85		68-136	NA
approximate current required to start and run	5	6750	84-140		112-124	NA

various types and sizes of 120 volt 60 cycle electric motors under various conditions.

The figures given above are for an average load such as a blower or fan. If the electric motor is connected to a hard starting load such as an air compressor, it will require more starting current. If it is connected to a light load or no load such as a power saw, it will require less starting current. The exact requirement will also vary with the brand or design of the motor.

Generators respond to severe overloading differently than power lines. When overloaded, the engine is not able to supply enough power to bring the electric motor up to operating speed. The generator responds to the high initial starting current, but the engine speed drops sharply. The overload may stall the engine. If allowed to operate at very low speeds, the electric motor starter winding will burn out in a short time. The generator head winding might also be damaged.

Running the generator under these conditions may result in damage to the generator stator as well as the electric motor windings. Because the heavy surge of current is required for only an instant, the generator will not be damaged if it can bring the motor up to speed in a few seconds. If difficulties in starting a motor are experienced, turn off all other electrical loads and if possible reduce the load on the electric motor.

5. Extension Cords

When electric power is to be provided to various loads at some distance from the generator, extension cords can be used. These cords should be sized to allow for distance in length and amperage so that the voltage drop between the generator and point of use is held to a minimum.

CAUTION: Equipment damage can result from the low voltage caused by using an extension cord with a small wire size.

Current/Power		Maximum Extension Cord Length
Amps	Load	#10 Ga	#12 Ga	#14 Ga	#16 Ga
at	(Watts)	Cord	Cord	Cord	Cord
240V
10	2400	250’	150’	100’	75’
20	4800	125’	75’	50’	25’
30	7200	60’	35’	25’	10’
40	9600	30’	15’	10’	*
50	12000	15’	*	*	*
				*Not Recommended

WARNING Keep a fire extinguisher close by your generator and be familiar with how to use it. Consult your local fire department for correct extinguisher type.

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