190 Detroit Street • Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468

PROCESS HEATER WIRING DIAGRAMSTYPICAL WIRING DIAGRAMS WITHOUT THERMOSTATS

L1 L2

Single-Phase - Series Connection

Element Voltage

Equals

One Half-Line Voltage

L1 Single-Phase - Parallel Connection

Element Voltage

Equals

Full Line VoltageL2

Process Heaters with Two Elements

Process Heaters with Three Elements

L2

L2

L2

L2

L2

L2

L1

L1 L1

L1

L1

L1Single Phase

Single Phase

L3

L3

L3L3

Three Phase Delta

Three Phase Delta

Three Phase Wye

Three Phase Wye

Standard process style heaters with three elements are factory wired for three-phasedelta. They can be rewired for single-phase operation with no wattage change. Wattage can be reducedto one third of the designed wattage by switching from three-phase delta to Wye connection.

Note: Dual-Voltage heaters are factory wired for the highestvoltage (series connection) unless otherwise speci�ed.Easily rewired for lower voltage operation (parallel connection).

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190 Detroit Street • Cary, Illinois 60013 • Phone: 847-639-5600 • Fax: 847-639-2199 • Web: www.durexindustries.com • TOLL FREE: 800-762-3468

PROCESS HEATER WIRE DIAGRAMSTYPICAL WIRING DIAGRAMS FOR HEATERS WITH THERMOSTATS

When Heater Amperage Does Not Exceed the Amperage of the Thermostat

L1

L2

Fused Disconnect

Heater

ThermostatSPST

L1

L2

L3

Fused Disconnect

ThermostatDPST

Heaters

120V Single-Phase Heater Three-Phase Heater

When Heater Amperage Exceeds the Amperage of the Thermostat

L1

L2

Fused Disconnect

Heater

ThermostatSPST

Magnetic Contactor

L1

L2

L3

Fused Disconnect

ThermostatDPST

Heaters

Magnetic Contactor

Fuses

Any Voltage Single-Phase Heater Three-Phase Heater

Use a Double Pole-Single Throw (DPST) thermostat wired in series with the holding coil of a magnetic contractor or mercury relay (pilot dury).

Use a Single Pole-Single Throw (SPST) thermostat wired in series with the holding coil of a magnetic contractor or mercury relay (pilot duty).

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