SPS NAC Field Wiring Guidelines, Continued
To connect the SPS to appliances using Class B wiring, read the following instructions
and refer to the figure below.
1. Route wire from the B+, B- outputs on TB2 of the SPS to the appropriate inputs
on a peripheral notification appliance. Use NAC1, NAC2, or NAC3, as required.
2. Route wire from the first appliance to the next one. “T” tapping is not allowed
since the spur will not be supervised. Repeat for each appliance.
3. Route wire from the last appliance to the supplied EOLR or a 4081-9008 EOL
Harness (10 K Ohm, ½ W; brown/black/orange).
4. Repeat steps 1 through 3 for each NAC output you want to use.
5. Leave the 378-030 EOL Resistor (10 K Ohm, ½ W; brown/black/orange) on
each unused circuit. The circuit must connect “B+” to “B-” terminals.
6. If the appliance/device to be used does not have an integral diode, a blocking
diode must be fitted between the incoming +ve wire and the +ve terminal of the
device with the diode‟s cathode (stripe) connected to the device.
The illustration below shows Class B wiring.
Figure 5-3. Class B (string) Wiring
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