Sears 8MPL075F16B1 Electrical Wiring, Power Supply Wiring, Box Relocation, Thermostat

9. Electrical Wiring

ELECTRICALSHOCK HAZARD.

Failure to follow safety warnings exactly could result in death or personal injury.

Turn OFF electrical power at fuse box or service panel before making any electrical connections and ensure a proper ground connection is made before connecting line voltage.

Power Supply Wiring

The furnace MUST be electrically wired and grounded in accor- dance with local codes, or in the absence of local codes, with the National Electrical Code (NEC), ANSI/NFPA 70-2002 in the U.S., or the Canadian Electrical Code (CEC), CSA C22.1 in Canada.

The power supply to the furnace connections must be between 104 VAC and 127 VAC during furnace operation for acceptable performance.

Field wiring connections must be made inside the furnace connec- tion box. A suitable strain relief should be used at the point the wires exit the furnace casing.

Copper conductors shall be used. Line voltage wires should

conform to temperature limitation of 63 ° F (35 ° C) rise. Wire and circuit breaker sizing shall be based on the ampacity of the furnace electrical components plus the amps for all installed accessories (1.0 amps total for EAC and HUM). Ampacity can be determined by using the NEC or CEC.

NOTE: Furnace will not have normal operation if line polarity is re- versed. Check ALL field and control connections prior to opera- tion.

Furnace must be installed so the electrical components are pro- tected from water and connected to its own separate circuit.

J- Box Relocation

N8MPN/L Models

The J-box is installed in blower compartment on left side of casing. An alternate J-box location on right side can be used.

1.Remove bag containing two hole plugs and two self-tapping screws from loose parts bag in blower compartment.

2.Remove and discard two screws holding J-box to casing.

3.Move large hole plug from right to left J-box location.

4.Move J-box to alternate location and attach using two self- tapping screws from bag.

5.Apply two hole plugs from bag at left J-box location.

6.Position all wires away from sharp edges and moving parts. Do not pinch J-box wires or other wires when reinstalling

blower compartment door.

*8MPN/L Models

The J-box is installed in the burner compartment on left side of casing. An alternate J-box location on right side can be used:

1.Remove and save two screws holding J-box to casing.

2.Move large hole plug from right to left J-box location.

3.Clip wire tie holding J-box wires.

4.Move J-box to alternate location and attach using two screws removed from left side location.

Position all wires away from hot surfaces, sharp edges, and moving parts. Do not pinch J-box wires or other wires when

reinstalling burner compartment door.

Thermostat

Thermostat location has an important effect on the operation of the

furnace. Follow instructions included with thermostat for correct

mounting and wiring.

Low voltage connections to furnace must be made on terminal board to furnace control. (See Figure 19)

If cooling is used, the Y from the thermostat must be connected to the control board Y to energize cooling blower speed.

Set thermostat heat anticipator in accordance with the Technical Support Manual.

Heat anticipator setting will need to be measured if 24VAC humidi- fier is installed. Measure currentin series from R to W at thether-

mostat. Be sure 24VAC humidifier is wired up to control. Allow furnace to operate for 2 minutes before recording the AC amper- age reading. Set anticipator on thermostat to recorded value.

Optional Equipment

All wiring from furnace to optional equipment MUST conform to lo- cal codes or, in the absence of local codes, the applicable national

codes. Install wiring in accordance with manufacturer's instruc- tions.

Humidifier/Electronic Air Cleaner

The furnace is wired for 115 VAC humidifier and/or electronic air cleaner connection.

REDUCED FURNACE LIFEHAZARD

Failure to follow caution instructions may result in reduced furnace life.

Do NOT exceed 115V/1.0 amp. maximum current

load for both the EAC terminal and the HUM terminal combined.

HUMIDIFIER - The 24VAC HUM is energized when the pres- sure switch closes on a call for heat. The HUM (115VAC) is en- ergized when the inducer is energized.

ELECTRONIC AIR CLEANER - EAC is energized when there is a blower speed call, except is NOT energized when blower operates in the hard-wired continuous fan mode.

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