System Mode Control Module Page - 5

NOTES:

1. Field Wiring - - - - -
2. Sensor Wiring does not normally require shielding. If the sensor wiring is routed through electrically noisy environments such as motor control centers, relay panels or lighting panel boards, shielded cable may be necessary to minimize electromagnetic interference. If using shielded cable, use the appropriate number of wires plus the shield and do not use the shield as one of the wires.
3. Do not run sensor wiring in the same conduit with, the same shielded cable with or next to relay motor control circuit or other switching wiring (including SMC outputs Y W and G) which may induce transient voltages.
4. Polarity (hot and common) must be maintained between connections on the SMC and the fan, cooling and heating relays.
5. Do not test for a live circuit by short circuiting. Damage caused by short circuiting will void the warranty.
6. Hook up wire and power requirements are shown in the table.
7. Maximum wire length and power requirements will change when using the optional 24 VAC mode signals or the optional add for duct heating stations. See specific wiring diagrams and wiring instructions.
8. 24 v. supply must be capable of powering 12 VA for the SMC plus the power requirements for the fan relay and either the cooling or heating relays. Since these relays are usually in the cooling/heating unit, the 24 v. transformer in that unit will be sized for the relays plus something for external controls which is usually sufficient for the SMC.
9. Cooling, heating and fan relays are required if not provided in the cooling/heating unit.
10. Using two wires in parallel will double the maximum wire length. If the maximum for 18 AWG is 36 ft. , two wires 18 AWG each per terminal have a wire length of 72 ft.
11. Multistage cooling/heating units require multistage discharge thermostats.
12. Delay on break anti short cycle time delays may be required for compressor protection. See the recommendations of the cooling/compressor unit manufacturer. The SMC time delays only operate with a change between heating and cooling. They will not protect from short cycling when the compressor comes back on after going off when the SMC stops calling for cooling and does not call for heating (between set points).
13. NEC CL2P cable approved for installation in ducts, plenums and other spaces used for environmental air is recommended where wiring to the sensors is in the return air plenum.
14. Dry contact switches (by others) are used for manual override, filter pressure and priority change.