8
• Some disconnect switches are not fused. Protect the
power leads at the point of distribution in accordance with
the unit’s data plate.
• The unit must be electrically grounded in accordance with
local codes or, in the absence of local codes, with the latest
edition of the National Electrical Code (ANSI-NFPA 70). A
ground lug is provided for this purpose. Size grounding
conductor in accordance with Table 250-95 of the National
Electrical Code. Do not use the ground lug for connecting
a neutral conductor.
• Connect power wiring to the electrical middle contactor
within the main control box of power block, if equipped.
Low Voltage
Terminal Strip
Thermostat wiring
for all units
connect to low
voltage strip
Ground
Lug
Line voltage connects
to power block on
Coolers and the 230v
Gas Packs
Line voltage connects
to middle contactor
on 460v and 575v
Gas Packs
(or power block
if equipped)
Power Block
(Coolers &
230V Gas Packs
Only)
Field wiring enters
from this direction
POWER AND LOW VOLTAGE BLOCK LOCATIONS
F
AILURE
OF
UNIT
DUE
TO
OPERATION
ON
IMPROPER
LINE
VOLTAGE
OR
WITH
EXCESSIVE
PHASE
UNBALANCE
CONSTITUTES
PRODUCT
ABUSE
AND
WILL
VOID
YOUR
WARRANTY
AND
MAY
CAUSE
SEVERE
DAMAGE
TO
THE
UNIT
ELECTRICAL
COMPONENTS
.
WARNING
Areas Without Convenience Outlet
It is recommended that an independent 115V power source be
brought to the vicinity of the roof top unit for portable lights and
tools used by the service mechanic.
NOTE: Refer to local codes for requirements. These outlets can
also be factory installed.
U
NITS
INSTALLED
ON
R
OOF
T
OPS
Main power and low voltage wiring may enter the unit through
the side or through the roof curb. Install conduit connectors at
the desired entrance locations. External connectors must be
weatherproof. All holes in the unit base must be sealed (including
those around conduit nuts) to prevent water leakage into build-
ing. All required conduit and fittings are to be field supplied.
Supply voltage to roof top unit must not vary by more than 10% of
the value indicated on the unit’s data plate. Phase voltage unbal-
ance must not exceed 2%. Contact your local power company for
correction of improper voltage or phase unbalance.
ELECTRICAL ENTRANCE LOCATIONS
Unit is equipped with Single Point Power Block and Low Voltage
Block.
L
OW
V
OLTAGE
C
ONTROL
W
IRING
1. A 24V thermostat must be installed for unit operation. It
may be purchased with the unit or field -supplied.
Thermostats may be programmable or electromechanical
as required.
2. Locate thermostat or remote sensor in the conditioned
space where it will sense average temperature. Do not
locate the device where it may be directly exposed to
supply air, sunlight or other sources of heat. Follow
installation instructions packaged with the thermostat.
3. Use #18 AWG wire for 24V control wiring runs not
exceeding 75 feet. Use #16 AWG wire for 24V control wiring
runs not exceeding 125 feet. Use #14 AWG wire for 24V
control wiring runs not exceeding 200 feet. Low voltage
wiring may be National Electrical Code (NEC) Class 2 where
permitted by local codes.
4. Route thermostat wires from sub-base terminals to the
unit. Control wiring should enter through the duct panel
(dimple marks entrance location). Connect thermostat and
any accessory wiring to low voltage terminal block TB1 in
the main control box.
NOTE:
Field-supplied conduit may need to be installed
depending on unit/curb configuration. Use #18 AWG solid
conductor wire whenever connecting thermostat wires to
terminals on sub-base. DO NOT use larger than #18 AWG wire. A
transition to #18 AWG wire may be required before entering
thermostat sub-base.
NOTE: Refer to unit wiring diagrams for thermostat hookups.
