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Why some pressure washers need certain Extension Cables

Why some pressure washers need certain Extension Cables

Marcus Nicholls |

DID YOU KNOW

Using a undersized extension cable can cause issues.

Using a 1mm² or 1.25mm² core extension cable with a pressure washer is generally not recommended and can be hazardous.

Pressure washers are high-power devices that draw significant current, and undersized cables (thin wires) cause substantial voltage drop over distance, leading to poor performance, overheating, and potential damage to the machine. 

 

1. Significant Voltage Drop and Underpowering 
  • Reduced Performance: As the voltage drops due to resistance in the thin, small-diameter cable, the pressure washer motor cannot pull enough power. This results in reduced pressure, "pulsing" water pressure, or the motor failing to start properly.
  • Motor Damage: Running an electric motor on low voltage causes it to draw more current to compensate, leading to overheating and significantly shortening the life of the machine. 

2. Overheating and Fire Hazard
  • Hot Cable/Plug: The high current draw, combined with high resistance from the thin 1mm/1.25mm wire, causes the extension cable and plug to get very warm or hot.
  • Melting Hazards: In extreme cases, this heat can melt the plug, socket, or the cable insulation, creating a serious fire hazard.
  • Tripping Breakers: The increased current draw is likely to trip the circuit breaker in your home or on the extension cable itself. 

3. Length Limitations
  • 1.25mm² Limit: Flexible, 1.25mm² cables should not generally exceed 12 meters (approx. 40 ft) in length when used for high-power tools.
  • 1mm² Limit: 1mm² cable is even more restricted and generally unsuitable for anything beyond very short, low-load use.

 

Recommendations
  • Use 1.5mm² or 2.5mm²: For a pressure washer, use a heavy-duty cable with a conductor size of at least 1.5mm² (for shorter distances) or 2.5mm² (for longer distances, up to 25m).
  • Use Shortest Cord Possible: Keep the extension lead as short as possible to minimize voltage drop.
  • Use RCD Protection: Ensure the extension lead is plugged into an RCD (Residual Current Device) protected socket.
  • Alternative: It is often better to use a longer high-pressure water hose and keep the electrical cord short. 

 
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