American Water Heater STCE3-52/80/119 ユーザーズマニュアル

Servicing should only be performed by a Qualified Service Agent

14

A three phase power supply consists of three wires connected to the L1, L2 and L3 terminals 
of the Power Distribution Block. All three wires are “hot” with voltage present.
Voltage Between Terminals: Set the volt meter to an AC voltage range above the expected 
voltage (600 VAC or higher range initially). Checking three phase (3Ø) power requires that 
three voltage readings be taken between all possible parings of the terminals on the Power 
Distribution Block. Carefully touch the two test probes between:

1 L1 and L2 terminals of the water heater’s Power Distribution Block
2 L2 and L3 terminals of the water heater’s Power Distribution Block
3 L1 and L3 terminals of the water heater’s Power Distribution Block

All three voltage readings should match the voltage listed on the water heater’s rating label 
by ± 5%.
Voltage to Ground: Check between each of the three terminals (L1, L2 and L3) of the 
Power Distribution Block and the ground wire connection inside the water heater’s control 
panel. On some 208 volt power supplies each reading will be approximately 120 volts to 
ground. Some 208 volt models will have a “stinger leg” with one of the three readings to 
ground measuring 208 volts - 208 volt stinger legs should be connected to L2. On 240 volt 
power supplies each reading should be approximately 120 volts to ground. On 480 power 
supplies each reading to ground should be approximately 277 volts.
Service Warning: Zero or low voltage readings between internal wiring and/or Power 
Distribution Block terminals and ground can be due to an inadequate earth ground. TREAT 
ALL WIRES AS BEING HOT until it has been determined there is no voltage present.
If the voltage readings taken between L1, L2 and L3 are more than ± 5% of the listed voltage 
on the water heater’s rating label or if the readings to ground were far less (at or near zero 
volts) than expected: check the fuses and the breaker and/or disconnect switch supplying 
power to the water heater. Contact a Qualified/Licensed electrician to restore power. If the 
voltage readings taken are a standard voltage (277/208/240/480) but do not match the listed 
voltage on the water heater’s rating label secure power to the water heater. DO NOT place it 
back in service. Contact the distributor and/or manufacturer to determine if the water heater 
can be field converted and/or replaced to match the power supply at the location.

(see Figures 1 & 2 on pages 8 and 9)