Kidde VM-1 Technical Reference Manual

Appendix A: System calculations
P/N 3101890-EN • REV 006 • ISS 21JUN18 171
Table 67 on page 172 through Table 70 on page 175 provide the maximum allowable branch length for any
detector, module, GSA-UM, and GSA-MAB and the wire gauge combination. Using the wire distances specified in
the tables ensures that the circuit does not exceed the maximum circuit resistance of the signaling line circuit.
Note: To calculate the wire distance with respect to circuit resistance, the tables assume that the circuit is end-
loaded (all devices are clustered more towards the end of the circuit) and the circuit uses standard non-shielded
wire.
To determine the maximum allowable length of a signaling line circuit branch:
1. Identify the device located farthest from the loop controller.
2. Determine the number of detectors, modules, and GSA-UMs or GSA-MABs configured for two-wire smokes
that lie on the same conductive path between the device identified in step 1 and the loop controller.
3. Calculate the number of detector and module addresses. Some modules require two addresses.
4. Determine the size of the wire used to construct the loop.
5. Find the maximum allowable wire distance for the longest branch in the lookup tables as follows:
If no GSA-UMs or GSA-MABs are installed, use Table 67 on page 172.
If 1 to 5 GSA-UMs GSA-MABs are installed, use Table 68 on page 173.
If 6 to 10 GSA-UMs or GSA-MABs are installed, use Table 69 on page 174.
If 11 to 15 GSA-UMs or GSA-MABs are installed, use Table 70 on page 175.

Kidde VM-1 Specifications

General

Brand	Kidde
Model	VM-1
Category	Fire Alarms
Language	English