Electrical Connections; Power Requirements; Three Phase Power Supply Connection - Patterson-Kelley STORM ST-2500 Installation & Owner's Manual

3.3 Electrical Connections

Power Requirements

The STORM boilers can be manufactured for 208-240 VAC, three phase, 60 hertz electrical service
OR 440-480VAC, three phase, 60 hertz electrical service. The total operating amperage is indicated on
the rating nameplate require less than 20 Amps at full load. Before starting the boiler, check to ensure
that the proper electrical service is connected to the boiler.
An external electrical disconnect and overload protection (not supplied with the boiler) are required.
NOTE: The STORM boilers MUST be ordered to the correct voltage! IT IS NOT POSSIBLE to
convert the boiler between the 240V and 480V configurations in the field!
Refer to Section 6.2, for proper wiring and configuration of the electrical connections. The electrical
service to the boiler must be installed and grounded in accordance with local codes or in the absence of
such requirements, in the U.S. with National Electrical Codes, ANSI/NFPA No. 70 latest edition or, in
Canada, to the current Canadian Electrical Code, Part I, CSA C22.1 latest edition. Installed conduit
must not block any of the boiler's openings and must allow the front door to be opened.

Three Phase Power Supply Connection

Main Power Connection Box
Always check the rating nameplate of the Storm boiler to determine the required electrical service:
•
208-240VAC, three phase, 60 hertz
•
440-480VAC, three phase, 60 hertz
The incoming three phase power for the ST-2500-ST-4000 boilers is connected to the over-current
safety device (rated for 20 Amps) and the Ground terminal located in the main power connection box.
The image on the next page shows the Low Voltage (TB1) and High Voltage (TB2) terminal blocks,
plus the Main Power Connection Box on the ST-2500-ST-4000.
•
Terminal 1 = HOT L1
•
Terminal 3 = HOT L2
•
Terminal 5 = HOT L3
•
Terminal G = GROUND
Control Transformer
The Main Power Connection Box features a Control Transformer which steps down two hot leads
from the incoming three-phase power in order to supply 110-120VAC single phase power to the
®
NURO control system. Be aware that Storm boilers ordered in the 240V configuration, are pre-wired
from the factory for operation with 240 VAC three phase incoming power.
NOTICE: If 208 VAC three phase power is supplied to the boiler, the internal control transformer
must be re-wired for operation at this lower voltage. The wire in terminal X3 on the load side of the
internal control transformer must be moved to terminal X4. This supplies 110 VAC power to the
®
NURO control from the 208 VAC main voltage.
configuration of the internal control transformer.
Revised: June 26, 2020
Released: June 26, 2020
Refer to Section
© Patterson-Kelley 2020
All Rights Reserved.
TM
P-K Storm Gas Fired Boiler
Technical Service 1.877.728.5351
7.2.4 for proper wiring and
2691000273 P-K Storm ST2500-ST4000
Installation and Owners Manual Rev A.docx
Page 14