ADT490 TroubleShooting Locating Grounds A

2 How are the Circuits Installed ‣ Before looking for the actual location of a fault on a circuit, look at how alarm circuits are actually installed in a building. ‣ Take a closer look at how the installer used 4-conductor fire cable in the installation of this circuit ‣ Go to the first junction box serving the detectors in suites 401 and 402. ‣ Find out: ‣ where does the circuit start on this floor – what and where is the first device? ‣ where is the last device on this circuit – and do we expect to find an EOL? 2

3 Fill In the Rest of the Circuit ‣ When we have a good idea of where the circuit arrives on the floor and where it ends, fill in the rest of the circuit run by using our eyes and common sense. ‣ Look at a simple example ‣ one of several floors in an apartment building ‣ Show the locations of initiating devices that make up Floor zone ‣ first the manual stations at each exit into the stairwell ‣ a heat detector in each suite ‣ now the storage closet and electrical closet ‣ 2 smoke detectors in the corridor ‣ EOL located adjacent to the last device 3

4 Apt Janitor closet Elect. West Stair East Stair If a reasonably accurate representation of location of devices It does not show how circuit that connects these devices is run. Floor Representation

5 Moving To Floor Layout ‣ From this “Representation” layout: ‣ end of the circuit is at the east end of the corridor ‣ devices installed one after the other on the Class B circuit ‣ one device follows another until we reach the EOL ‣ A “Floor Layout” perspective the conduit run connecting devices could look as indicated on the next slide 5

6 Floor Layout

7 ‣ Now how could the wire circuit could be run in the conduit and through the junction boxes. Wiring Run

8 Wiring Aids ‣ Take a closer look: ‣ How the installer used 4-conductor fire cable in the installation of this circuit ‣ Go to the first junction box serving the detectors in suites 401 and 402 ‣ The two most popular fire alarm cables are “2-wire” and “4-wire” ‣ Individual conductors have coloured insulation that helps us indicate polarity. 8

9 5 Connecting the detectors in 401 and 402: Pair of wires coming from Zone 4 of the FACP The next device is a smoke detector. Its wiring terminals connect to the feed from the FACP. Red & Brown = +ve Black & Blue = -ve

10 Establishing The Midpoint ‣ Having a reasonable idea as to how the circuit wiring is run ‣ “Stretch out” the circuit ‣ This allows us to make an accurate guess as to the mid-point ‣ See next Slide 10

11 Zone 1 Zone 2 Zone 3 Zone 4 Initiating Circuits (Inputs) This is the 7 th device in a circuit 0f 14 devices, including 2 junction boxes Elect. Rm closet Stretched Circuits

12 end of presentation