A knife switch is a simple, mechanical on/off or transfer device that opens and closes an electrical circuit. You’ll see it used in a few ways:

• Isolation/disconnect: Manually cut power for maintenance or safety.
• Transfer or reverse: Route a circuit between two positions (double-throw designs).
• Demonstrations: Classroom and lab models for learning basic circuit concepts.
• Specialty tasks: Options like electric fence cut-off switches or generator backup (when appropriately rated).

Models on this page range from low-voltage lab styles to higher-amperage disconnects. Always match the switch type and rating to your application, and for permanent or high-voltage installs, consider consulting a licensed electrician to ensure proper selection and compliance.

It comes down to how many circuits you need to control and how many positions you want:

• SPST (Single Pole, Single Throw): One circuit, on/off only. Great for basic disconnects.
• SPDT (Single Pole, Double Throw): One circuit, two selectable positions (A or B).
• DPDT (Double Pole, Double Throw): Two circuits switched together between two positions—helpful for reversing polarity or transfer setups.
• 2P/3P/4P: Indicates how many separate lines (poles) switch at once; pick the pole count to match the number of conductors you need to switch.

If you’re unsure, review the wiring diagram on the product page and consider your circuit layout. When in doubt for fixed installations, a licensed electrician can help confirm the right configuration.

Choose a rating that meets or exceeds your circuit’s requirements:

• Current (A): Match or exceed the maximum load. You’ll find options commonly labeled around 32A, 63A, or 100A.
• Voltage (V): Pick a switch with a voltage rating equal to or higher than your system (examples on this page include AC 220V and 380V models).
• AC vs. DC: Ratings can differ; confirm the switch is suitable for your power type.
• Headroom: Some users select a higher rating for extra margin, but oversizing without reason isn’t always necessary.

Always verify the specs shown on the product detail page against your application. For permanent or higher-power circuits, consulting a licensed electrician is advisable.

Some double-throw knife switches are marketed for generator backup, but using one depends on local codes and your setup. To evaluate fit:

• Double-throw design: Lets you select between two sources (utility or generator) without both connected at once.
• Adequate rating: Match or exceed your generator’s amperage and system voltage.
• Pole count: Ensure enough poles to switch all required conductors per local requirements.
• Safety features: Look for clear ON/OFF indicators and protective enclosures.

Many jurisdictions require a listed transfer switch for interconnection. Because requirements vary, it’s a good idea to consult a licensed electrician and follow local electrical codes before purchasing.

Classroom knife switches are commonly used for low-voltage demonstrations when used appropriately. For safer, easier setup:

• Choose education-focused models: Look for SPST or DPDT switches with stable bases and screw posts.
• Use low-voltage sources: Batteries or low-voltage power supplies are typically recommended for demonstrations.
• Keep hands off live conductors: Tighten connections and avoid touching exposed metal when energized.
• Supervision and storage: Adult supervision is important; store components securely after use.

Never connect classroom switches to household mains. Check the product’s specifications and any included safety notes, and follow your institution’s lab safety guidelines during use.