Electric motor driven pressure washers that require single phase 115 volt or single phase 230 volt electrical power can optionally be supplied by a separate portable engine driven generator. However, use of a generator requires that the operator strictly comply with the following guidelines to avoid serious problems with the pressure washer and/or generator.

1. The generator must be sized to handle the inrush current drawn by the electric motor on start up. All electric motors on all types of equipment pull a very high level of amperage for less than one second on start up. This is called inrush current. When equipment is plugged into a building power outlet, the inrush current is easily handled by the power grid because the inrush current represents only a tiny fraction of the current (amperage) available from the power utility. However, when a portable generator is used, the inrush current represents as much as 100% of generator capacity. If the generator capacity (kw rating) is not enough to handle the inrush current, the electric motor and/or generator can be severely damaged. The minimum size generator that can be used with your pressure washer can be determined, if necessary, by contacting customer service at Spartan Mfg.Corp at (336)m 996-5585 Eastern Time.
2. The proper size of power cord must be used and the length should be as short as possible. Sizing of power cord is indicated by AWG (American Wire Gauge) frequently called “wire gage”. The minimum size of the cord/cable between the generator and pressure washer is 12 gage up to 50 ft. long for motor sizes of 3 H.P. or less. For 5 H.P. motors 10 gage cables are needed up to 50 ft. in length. The smaller the gage number, the heavier the cord/cable and higher the current carrying capacity. For cord/cable lengths longer than 50 ft. in length you should contact Spartan customer service for engineering guidance. Using an undersized power cord can result in pressure washer damage from low voltage even with a properly sized generator.
3. The generator must be started with no load and allowed to come up to full speed and stabilize the voltage output (several seconds) before putting any load on it. Generator voltage output is directly proportional to generator speed (RPM). It is ok to have the pressure washer plugged in to the generator when the generator is started, but the pressure washer must not be turned on until the generator is up to speed and stabilized. Failure to follow this procedure will result in severe damage to the pressure washer and/or generator. Before shutting down the generator, the load (pressure washer) must be shut off for the same reason.
4. If another load (other equipment) is connected to the generator in addition to the pressure washer, the size of the generator may need to be increased. Contact Spartan customer service for engineering assistance in determining proper generator size for multiple loads. After the generator is running and stabilized, it is very important to stagger switching on the connected loads one at a time with 3-5 second intervals between to avoid simultaneous inrush current loads. For the pressure washer, first turn on the pump and 3-5 seconds later, turn on the burner. When switching off loads they should be cut off one at a time to avoid voltage fluctuation from the generator.