Lennox EL280UHX Series Unit Information page 29

I- Proper Ground and Voltage
Furnace must be properly grounded for proper perfor-
mance. Use the following procedure to check for ground
and voltage to the integrated control.
1 - Measure the AC voltage between Line Neutral
(spade terminals) and "C" terminal (low voltage
terminal block) on the integrated control. See
FIGURE 21. A wide variation in the voltage between
Line Neutral and "C" as a function of load indicates a
poor or partial ground. Compare the readings to the
table below. If the readings exceed the maximum
shown in TABLE 16, make repairs before operating
the furnace.
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE "C" TERMINAL
2 - In addition, measure the AC voltage from Line Hot
to Line Neutral (spade terminals) on the integrated
control. See FIGURE 21. This voltage should be in
the range of 97 to 132 Vac.
Furnace Status
Power On Furnace Idle
CAI / Ignitor Energized
Indoor Blower Energized
CHECK VOLTAGE BETWEEN LINE HOT
AND LINE NEUTRAL
FIGURE 21
Page 29
TABLE 16
Measurement VAC
Expected Maximum
0.3
0.75
Less than 2
2
5
10