Typical Wiring Diagrams - A.O. Smith NW 37-670 Instruction Manual

Boiler Type
Nameplate of
Markings Service
Voltage Phase
1
208
3 Delta
(With
Neutral)
1
240
3 Delta
480 3 Wye*
480 3 Delta
* Neutral lug not necessary and not furnished due to three wire wye connection. This means only three wires (no neutral)
brought to boiler due to method of element connection. Elements operate at 277 volts.
Voltage from a conductor to ground (electrical raceway and water pipes) is not measured.
No ground lug furnished. If required installer can provide locally.
WIRING DIAGRAM 208V OR 240V THREE-PHASE (DELTA) WITH STEP CONTROL
ELECTRICAL CONFIGURATION TABLE
Voltage Between
Boiler Terminal
Lugs
L1 L2 N G
208
120
L1 L2 L3 N G
208
208
208
120
L1 L2 G
240
L1 L2 L3 G
240
240
240
L1 L2 L3 G
480 480
480
L1 L2 L3 G
480 480
480

TYPICAL WIRING DIAGRAMS

The following wiring diagrams are included in this manual to show
typical arrangements of electrical components in the control and
power circuits by voltage and phase charactreristics. They are
to be used as a reference by the installer or servicer in performing
their work. A diagram of the boiler wiring is furnished with the
boiler.
Control
Circuit
Voltage
(1 Phase)
120
120
120
120
120
120
8
Elements
Quantity Element
Per Operating
Contractor Voltage
1 208
1 208
1 240
1 240
1 or 2 277
1or 2 480