230v Switch: Buzzing Sound When Pressing the Start Button

Created by Gabriel Izzo, Modified on Thu, 21 May at 12:22 PM by Gabriel Izzo

Harvey FAQ · Power & Electrical

230V Switch — Buzzing Sound When Pressing the Start Button

North American Machines Only

Voltages and standards referenced in this article apply only to North American machines. Please consult with a licensed electrician before proceeding with any electrical checks or modifications.

⚠ Electrical Safety

Do not attempt to inspect or modify electrical wiring yourself unless you are a licensed electrician or q. Working on live circuits or mains wiring can cause serious injury or death.

Turn off and lock out the circuit breaker at the panel before inspecting any wiring at the receptacle or inside the machine's electrical enclosure.

Use a properly rated multimeter when testing voltage at a receptacle. Wear rubber-soled footwear, keep the work area dry, and do not test live circuits alone.

Do not continue operating the machine if it is buzzing, chattering, or failing to start — these symptoms indicate a power supply issue that must be resolved before resuming use.

Noisy Contactor Diagnosis

If the machine's contactor is making a chattering, humming, or buzzing sound and fails to start, this is most likely caused by an incomplete or improper power supply.

Most Common Cause

An incorrect circuit breaker is installed — for example, a single-pole breaker instead of the required double-pole.

One of the hot wires (commonly the white wire) was not converted from neutral to hot at the panel — this is common when a circuit was previously wired for 115V and later repurposed for 230V.

Either condition results in only one hot leg supplying 115V rather than two hot legs supplying the required 230V. This prevents the contactor coil from receiving enough voltage to engage — causing the buzzing or chattering sound.

How to Fix It — Verification Checklist

Verify the following with a licensed electrician

Circuit

Machine is connected to a dedicated 240V / 20A circuit.

A 240V double-pole breaker is installed — not a single-pole.

Receptacle

A NEMA 6-20R receptacle is installed to match the NEMA 6-20P plug on the machine.

Voltage Test

The receptacle delivers 110–120V on each hot leg, for a combined total of 220–240V across both legs.

Grounding

The ground wire is securely connected and properly grounded at the panel.

Machine Circuit Breaker (if applicable)

Check the built-in circuit breaker on the machine's switch. If it has tripped, reset it and attempt to start the machine again.

If the issue persists after verifying all of the above, please contact our support team.