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7.1 Electrical Field Connection Descriptions
Standard Electrical Connections
1. Primary high-voltage entrance—2-1/2" (64mm); 1-3/4" (44mm); 1-3/8" (35mm) diameter
concentric knockouts located in bottom of box.
2. Secondary high-voltage entrance—2-1/2" (64mm); 1-3/4" (44mm); 1-3/8" (35mm) diameter
concentric knockouts located in top of box.
3. Primary low-voltage entrance—Three 1-1/8" (28mm) diameter knockouts in bottom of unit.
4. Secondary low-voltage entrance—Three 1-1/8" (28mm) diameter knockouts in top of box.
5. Three-phase electrical service—Terminals are on high-voltage terminal block (disregard if
unit has optional disconnect switch). Three-phase service not by Emerson.
6. Earth ground—Terminal for field-supplied earth grounding wire.
7. Remote unit shutdown—Replace existing jumper between terminals 37 and 38 with
field-supplied normally closed switch having a minimum 75VA, 24VAC rating. Use field-supplied
Class 1 wiring.
8. Customer alarm inputs—Terminals for field-supplied, normally open contacts, having a
minimum 75VA, 24VAC rating, between terminals 24 and 50, 51, 55, 56. Use field-supplied
Class 1 wiring. Terminal availability varies by unit options.
9. Liebert SiteScan
®
—Terminals 77(-) and 78(+) for a two-wire, twisted pair, communication cable
(available from Emerson) to optional Liebert SiteScan.
10. Common alarm—On any alarm, normally open dry contact is closed across terminals 75 and 76
for remote indication. 1A, 24VAC max load. Use Class 1 field-supplied wiring.
11. Heat rejection interlock—On any call for compressor operation, normally open dry contact is
closed across terminals 70 and 71 to heat rejection equipment. 1A, 24VAC max load. Use Class 1
field-supplied wiring.
Optional Electrical Connections
12. Factory installed disconnect switch.
13. Secondary disconnect switch and earth ground.
14. Three-phase electrical service—Terminals are on top of disconnect switch. Three-phase
service not by Emerson.
15. Smoke sensor alarm—Factory-wired dry contacts from smoke sensor are 91-common, 92-NO
and 93-NC. Supervised contacts, 80 and 81, open on sensor trouble indication. This smoke sensor
is not intended to function as, or replace, any room smoke detection system that may be required
by local or national codes. 1A, 24VAC max load. Use Class 1 field-supplied wiring.
16. Reheat and humidifier lockout—Remote 24VAC required at terminals 82 and 83 for lockout of
reheat and humidifier.
17. Condensate alarm (with condensate pump option)—On pump high water indication,
normally open, dry contact is closed across terminals 88 and 89 for remote indication. 1A, 24VAC
max load. Use Class 1 field-supplied wiring.
18. Remote humidifier—On any call for humidification, normally open dry contact is closed across
terminals 11 and 12 to signal field-supplied remote humidifier. 1A, 24VAC max load. Use Class 1
field-supplied wiring.
19. Auxiliary-cool contact—On any call for Econ-O-Coil operation, normally open dry contact is
closed across terminals 72 and 73 on dual-cool units only. 1A, 24VAC max load. Use Class 1
field-supplied wiring.