Carrier RTU OPEN 11-808-427-01 - Manual (Page 13)

RTU Open 7
Screw the RTU Open into an enclosed panel using the mounting slots on the cover plate. Leave about 2 in. (5
cm) on each side of the controller for wiring.
To wire the controller for power
CAUTIONS
• The RTU Open is powered by a Class 2 power source. Take appropriate isolation measures when
mounting it in a control panel where non-Class 2 circuits are present.
• Do not power pilot relays from the same transformer that powers the RTU Open.
• Carrier controllers can share a power supply as long as you:
○ Maintain the same polarity
○ Use the power supply only for Carrier controllers
• The RTU Open has an operating range of 21.6 Vac to 26.4 Vac. If voltage measured at the RTU Open's
input terminals is outside this range, the RTU Open may not work properly.
○ In most cases, the RTU Open will be powered from the control power transformer provided with the
rooftop equipment. If you must use a separate control power transformer, additional precautions
must be taken to ensure that the auxiliary transformer is in-phase with the rooftop equipment’s
control power transformer. See Using an auxiliary control power transformer (page 8).