Connect Wiring

General wiring requirements:

Electric shock hazard. Can cause severe personal injury or death if

power source, including service switch on boiler, is not disconnected before installing or servicing.

Installations must follow these codes:

National Electrical Code, ANSI/NFPA 70, latest edition and any additional national, state or local codes.

In Canada, CSA C22.1 Canadian Electrical Code Part One and any local codes.

Wiring must be N.E.C. Class 1. If original wire as supplied with boiler must be replaced, type 105°C wire or equivalent must be used. Supply wiring to boiler and additional control wiring must be 14 ga. or heavier.

Provide electrical ground at boiler as required by codes.

Thermostat wiring:

Install thermostat on inside wall away from influences of drafts, hot or cold water pipes, lighting fixtures, television, sun rays or fireplaces.

Follow instructions with thermostat. If it has a heat anticipator, set heat anticipator in thermostat to match power requirements of equipment connected to it. Boiler wiring diagrams give setting for standard equipment.

Junction box (furnished):

Junction box houses electrical connections for all boiler components.

“P” boilers have harnesses furnished.

“A” boilers are furnished with burner and limit harnesses.

All field-provided high voltage wiring must be sheathed in flexible metal conduit.

Connect incoming line voltage “HOT” wire to service switch, and neutral wire to white wire. Field-install equipment ground wire to green wire with wire nut.

Service switch (15 amp) is provided with boiler. “A” boilers — install switch as shown.

Some local codes may require an emergency shut-off switch installed at a location away from boiler. Follow local codes.

Burner wiring:

Burner harness incorporates a disconnect plug, providing a convenient way to disconnect wiring when burner mounting door is opened.

All “P” boilers have a power disconnect plug installed on burner.

On “A” boilers, mount the plug (provided in steam trim carton) on the burner housing as shown in FIGURE 13 or 14. For Carlin burners, screw burner plug into threaded conduit coupling, then mount this assembly to the burner housing using the chase nipple. Route wires through housing and make connections in burner junction box as shown in boiler wiring diagram.

To wire boilers, refer to the following pages:

Pages 20 to 21 Float-Type LWCO

Pages 22 to 23 Probe-Type LWCO

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Weil-McLain 550-141-829/1201 manual Connect Wiring, General wiring requirements, Thermostat wiring, Junction box furnished