Preparation & Installation

Before You Begin

• Always hire a licensed electrician. Improper wiring can cause fires, equipment damage, or injury.
• If installing in a public facility (e.g., a school or community center), get approval from the owner or administrator beforehand.
• Select an Installation Location that meets code requirements, minimizes wiring distance, and allows for convenient maintenance.
• Before purchasing a kiln, review its spec sheet to ensure its voltage, amperage, and phase requirements match your building’s supply.

Data Nameplate

• The kiln’s Data Nameplate (usually found on the control panel) also lists voltage, amperage, and phase requirements.
• Review these details with your electrician before installation to confirm proper circuit sizing and component selection.

Voltage

• L&L kilns require a variety of voltages, ranging from 120 V - 480 V. Always match the kiln’s rated voltage to your supply.
  • Example: A 208 V kiln on a 240 V supply will overheat, creating a fire hazard; a 240 V kiln on a 208 V supply will be inefficient and may never reach the desired temperature.
• A ±7 volt range is an acceptable tolerance, but larger deviations shorten element life and affect firing capacity.
• Voltage may vary by time of day and location. Use a transformer or change elements to align with your building’s supply if necessary.

Amperage & Circuit Sizing

• The NEC requires circuits to be rated at 125% of the kiln’s maximum amperage.
• To determine circuit size, multiply the kiln’s maximum amperage by 1.25, then select the next standard breaker size.
  • Example: A kiln rated at 48 A requires a 60 A breaker (48 × 1.25 = 60). A kiln rated at 60 A requires an 80 A breaker (60 × 1.25 = 75)
• Use a dedicated circuit to avoid overloads and potential fire hazards.

Phase

• Ensure the kiln’s phase (single or three-phase) aligns with your building’s electrical service.
• Residential buildings in the U.S. commonly provide single-phase power, while commercial or institutional settings often have three-phase. Always verify before proceeding.
• Three-phase circuits are balanced on three-section (27" high) kilns. Other heights (such as 18", 22", 36", or 45") are not inherently balanced unless specifically designed for that purpose.

Wiring

• IMPORTANT: Always use copper wire (preferably braided) rated for at least 75°C.
• Never use aluminum wire, which oxidizes under kiln conditions and creates a fire hazard.
• Select wire gauge based on the breaker size and the run length. 

Wire Size Chart and Maximum Amp Ratings

In the U.S., a special scale has been developed for the most common wire sizes. This is the American Wire Gauge, or AWG. The following table is based on the 1999 National Electric Code®, Tables 310-16 and 310-18. These are the allowable ampacities of Insulated Conductors, (3) current-carrying conductors in a raceway or cable, and are based on an ambient temperature of 86°F. 105°C values are estimated using 1.15 × the 90°C ampacity.

This is only a starting point. Your electrician must consider the number of conductors in the raceway, ambient temperatures, and the wire run length. 

Note: Our recommended wire connection ratings are based on 75°C wire.

• Locate the kiln within 50' of the breaker.
• Longer distances result in voltage drop and may require an increase in wire gauge. Review this page for more information.
• Route wiring through appropriate conduit and keep it away from the kiln’s hot surfaces to reduce the risk of damage and fire hazards.

Grounding

• Ensure a dedicated ground conductor is installed; never use the ground as a neutral. 
• Note: L&L does not use the Neutral at all except for some ancient kilns.
• Proper grounding helps protect against electrical shock and ensures safety devices function correctly.

Fused Disconnect Switch

• Consider installing a fused disconnect switch with a lockout provision near the kiln.
• Provides a reliable means to cut power, preventing unauthorized use and reducing wear on plugs and outlets.
• Ideal for lockout/tagout procedures in industrial or institutional settings, ensuring safe maintenance and inspections.

Plugs & Receptacles (If Applicable)

• For kilns rated at 48 A or less, L&L typically supplies a factory-fitted cord and plug, most commonly a NEMA 6-50P (single-phase) or 15-50P (three-phase). Kilns for markets outside North America do not include a cord.
• Have your electrician install a matching, properly rated receptacle so the cord hangs downward and maintains a secure connection.
• Do not rely solely on unplugging for routine shutoff. A fused disconnect or dedicated breaker switch is safer and more reliable over time.
• Never use an extension cord for a kiln; always plug directly into the receptacle.

Note about Plug and Fuse Ratings:

1. L&L Kiln uses a UL499 listed NEMA 6-50P or 15-50P plug and cord that is robustly designed and marked for 50 amperes at up to 250 Volts AC, 1 Phase (or 3 phase for the 15-50P), with a grounding prong. The (2 or 3) current carrying conductors are 6 AWG, which according to the 2002 NEC (National Electrical Code) Table 400.5 for flexible cables have an allowable ampacity of 55 amperes, and the grounding conductor is 8 AWG, which does not usually carry any current. The plug, or cap, is designed and constructed so there are no exposed current-carrying parts except for the prongs, which only carry current when the plug or cap is safely inserted into its mating receptacle.
2. This plug and cord set is listed for carrying 50 amperes at the proper voltage and phase. All L&L kilns that use these plugs and cords are also listed as complete appliances, with the ratings listed in L&L Kiln Mfg., Inc. catalogs. When installed, the circuit that supplies power to the kiln must be designed per NEC requirements, and in many cases must be provided with conductors and overcurrent protection rated for 60 amperes, or 125% of the ampere listing of the kiln. (E.g., the E23T is listed at 48 amperes. 48 * 1.25 = 60 ampere rating for overcurrent protection and power supply conductor rating.) This may initially create some confusion, but remember that the kiln is UL listed with the NEMA 6-50P plug and cord set as a component of the appliance - it is the power supply circuit that must be protected at 125% of the listed rating, not the individual components inside the appliance.

Hardwired Installations

• Kilns rated above 48 Amps must be hardwired directly to a fused disconnect or breaker panel.
• Use flexible conduit to run wiring from the panel to the kiln’s control box, then connect the conductors to the internal power connection block.
• Because of the many possible installation variations, L&L does not provide materials or cables for hardwiring.
• For kilns drawing 48 Amps or less, hardwiring is optional and may be preferred for added security.
• If performed correctly, hardwiring does not void the warranty. Consult a licensed electrician and follow all applicable codes and guidelines.
• If you are hardwiring the kiln, the wire that connects to the kiln's terminal block should be rated for 105°C 

Final Checks & Initial Testing

• Verify that all connections are secure and properly tightened.
• Ensure no wires, cords, or plugs touch the kiln's exterior.
• Confirm the kiln is properly grounded and that safety devices (such as fused disconnects or circuit breakers) function correctly.
• Briefly power the circuit (with the kiln off) to confirm the breaker holds and check for any unusual odors or sounds.
• If anything appears incorrect or unsafe, shut down power immediately and consult your electrician before proceeding.