Specifications

Diagrams are for reference only.

Consult the appropriate installation sheet for wiring details.

SAC BUS POWERSAC BUS POWER

SAC BUS POWER

REFERENCE SECTION

Providing adequate voltage for devices

To determine whether each CRC and KPDISP will have adequate input voltage,

calculate the voltage drops along the SAC bus. Voltage drops can be estimated or

actual.

Estimated voltage drop

To estimate the voltage drop use Table D-1 and Table D-2, which show the maximum

wire length for a given number of doors at a given current load. The tables assume

even spacing between the doors and an equal load at each door.

1. First, determine the load per door by adding the alarm currents of the CRC, door

lock, card reader, and sounder.

2. Determine the number of doors you need to secure. Find the number of doors

Table D-1 then search across that row for the column with the current you

calculated in step 1.

3. The intersection gives the maximum distance from the 3-PPS/M or remote power

supply to the last door.

4. If the distance to the last door in your installation is less than this distance no

further calculations are needed.

5. If the distance to the last door in you installation is greater than this distance

check TYable D-2 using steps 1 through 4.

6. If changing the gauge of the wire does not work, you must run a second power

line, or divide the SAC bus and add a remote power supply. In either case, recheck

your estimates.

For example: You are putting a CRC, a strike rated at 250 mA @ 12 Vdc, a CR-5395

and a CRCSND at 8 doors. The furthest door is 500 feet from the control.

Using step 1 above, you determine that the total alarm current for this door is 149

mA. In Table D-1 (for 16 AWG), find 8 in the Doors column, go across this row to the

150 mA column. The intersection shows a maximum length of 584 feet. Since the

distance from the control panel to the last door is less than 584 feet, no further

calculations are needed.

Actual voltage drop

To calculate the actual voltage drop based on the actual load for each device and the

actual distance between each device, follow the steps on the next page.