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JANUARY 2008 UCCS STANDARDS 15950-27
2.12 AUXILIARY DEVICES - ELECTRIC
A. Flow-proving or equipment-operating-status switches shall be paddle, differential-pressure,
or current-sensing types as indicated below.
1. Paddle-type switches (water service only) shall be UL-listed, SPDT snap-acting with
pilot duty rating (125 VA minimum). Adjustable sensitivity with NEMA 1 enclosure
unless otherwise specified.
a. Paddle switches shall be used to prove flow through boilers, chillers, and other
applications where actual flow must be confirmed to protect equipment, or for
other safety reasons.
2. Differential-pressure-type switches (air or water service) shall be UL-listed, SPDT
snap-acting, pilot duty rated (125 VA minimum), NEMA 1 enclosure, with scale
range and differential suitable for intended application, or as specified.
3. Current-sensing-type sensor shall be used to prove equipment operation in those
applications . Current-operated switches shall be self-powered, solid state clamp on
with adjustable trip current and led. The switches shall be selected to match the
current of the application.
B. Damper end-switches shall be UL-listed, line voltage SPDT snap-acting, pilot duty rated
(125 VA minimum)
C. Control relays shall be UL-listed, plug-in type with dust cover and a "energized" indication
light. Contact rating, configuration, and coil voltage suitable for application. Provide
diodes to limit back EMF on all DC relays and MOVs on AC. IDEC, or approved equal.
D. Time-delay relays shall be UL-listed, solid-state, plug-in type with adjustable time delay.
Delay shall be adjustable plus or minus 200% (minimum) from setpoint shown on plans.
Contact rating, configuration, and coil voltage suitable for application. Provide NEMA 1
enclosure when not installed in local control panel.
E. Control transformers shall be UL-listed, Class 2 current-limiting type, or shall be furnished
with overcurrent protection in both primary and secondary circuits for Class 2 service.
F. Manual control switches shall be UL-listed for use in NEMA 1 enclosures with contact
arrangement and rating suitable for application. Bat handle or knob actuator with
nameplate clearly identifying function of each switch position.
G. Override timers shall be spring-wound, line-voltage, UL-listed, with a contact rating and
configuration as required by the application. Provide 0 to 6-hour calibrated dial unless oth-
erwise specified; suitable for flush mounting on control panel face, located on local control
panels or where shown on plans. Timers shall not be provided with a hold or override
feature.