Engineering Documentation

Table Of Contents
Chapter 3 Field Panels
PX Series Service Boxes
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Low voltage is routed from the transformer and supplies 24 Vac power at either 192
VA or 384 VA maximum. The CTLR and PS connectors are rated Class 1 power
limited and connected equipment must reside in the enclosure with the service box.
The Class 2 connector is limited to 96 VA and may also be connected to equipment
outside of the enclosure. A MOV (30V) is installed on the transformer secondary. See
the following figure for a wiring diagram.
Fig. 49: Wiring Diagram for 115V Service Box (192 VA or 384 VA).
PX Series 230V Service Boxes (192 VA or 384 VA)
230V (high-voltage) source power to the service box enters the enclosure from the top
right or right-hand side conduit knockouts. Source voltage must be current limited to
10 amps or less, depending on the requirements of the particular installation.
A termination block for power and ground termination is provided on the wire cover for
easy connection by an electrician. The termination block is pre-wired to the
transformer through a double pole On/Off switch and a circuit breaker. MOVs (3 ×
275V) are installed on input power. Termination block earth ground (green/yellow),
transformer secondary neutral (green) and Service Box earth ground (green/yellow)
have ring terminals for mounting on earth ground stud.