Announcement

Collapse
No announcement yet.

T Tap FA Device

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    T Tap FA Device

    What takes place when you t tap? Thanks.

    #2
    Originally posted by mstrlucky74 View Post
    What takes place when you t tap? Thanks.
    T-Tap would be when you wire in a star configuration vs a series configuration (ie one cable in and one out). This is done on the signal line circuit in programmable systems which are specified as Class B wiring. This is not allowed in a Class A wiring style and is not allowed on the notification appliance circuit regardless of class.

    Example of a t-tap would be a homerun from the FACP to an initiation device and the leaving that initiation device with separate runs to several other initiation devices ( one cable in and 2+ out).

    1N73LL1G3NC3 15 7H3 4BILI7Y 70 4D4P7 70 CH4NG3.

    Comment


      #3
      Also, in conventional systems, T-taps result in loss of supervision of the T-tap conductors. In addressable systems T-taps generally cause no issues, since each device is "known" by the control panel. But even with addressable systems, T-tapping is allowed only when approved in the manufacturer's installation instructions. Some addressable systems (EST) need to be T-tapped to operate properly.

      Comment


        #4
        Originally posted by luckylerado View Post
        T-Tap would be when you wire in a star configuration vs a series configuration (ie one cable in and one out). This is done on the signal line circuit in programmable systems which are specified as Class B wiring. This is not allowed in a Class A wiring style and is not allowed on the notification appliance circuit regardless of class.

        Example of a t-tap would be a homerun from the FACP to an initiation device and the leaving that initiation device with separate runs to several other initiation devices ( one cable in and 2+ out).
        Thanks...have some temporary heat detectors and they said we can t-tap.

        Comment


          #5
          Originally posted by GrayHair View Post
          Also, in conventional systems, [COLOR="#FF0000"]T-taps result in loss of supervision of the T-tap conductors.[/COLOR] In addressable systems T-taps generally cause no issues, since each device is "known" by the control panel. But even with addressable systems, T-tapping is allowed only when approved in the manufacturer's installation instructions. Some addressable systems (EST) need to be T-tapped to operate properly.
          In most cases, yes. Someone whom I can't recall had a panel where you could put ONE T-tap on the IDC, terminating both branches with resistors of double the normal value.

          Comment


            #6
            Originally posted by gadfly56 View Post
            In most cases, yes. Someone whom I can't recall had a panel where you could put ONE T-tap on the IDC, terminating both branches with resistors of double the normal value.
            In theory, this works but in practice this is a cheat and I doubt that any panel manufacture product data would support it. Talk about a trouble shooting nightmare.

            1N73LL1G3NC3 15 7H3 4BILI7Y 70 4D4P7 70 CH4NG3.

            Comment


              #7
              Originally posted by luckylerado View Post
              In theory, this works but in practice this is a cheat and I doubt that any panel manufacture product data would support it. [COLOR="#FF0000"]Talk about a trouble shooting nightmare[/COLOR].
              I agree, but I remember being astonished when I read it in the manual.

              Comment


                #8
                Originally posted by GrayHair View Post
                ..... Some addressable systems (EST) need to be T-tapped to operate properly.
                That statement is demonstrably untrue in regards to EST (including FAST & private labeled EST based) systems.
                In battle, in forest, at the precipice in the mountains,
                On the dark great sea, in the midst of javelins and arrows,
                In sleep, in confusion, in the depths of shame,
                The good deeds a man has done before defend him.
                --Bhagavad-Gita

                Comment


                  #9
                  Originally posted by MichaelGP3 View Post
                  That statement is demonstrably untrue in regards to EST (including FAST & private labeled EST based) systems.
                  I'm afraid you are incorrect. I ran into it on a EST-2 that had been originally installed with no T-taps, and expanded with no T-taps. It wouldn't map and the only way I could get it to do so was to do some T-tapping.
                  I didn't understand it and neither did tech support.

                  Comment


                    #10
                    Originally posted by GrayHair View Post
                    I'm afraid you are incorrect. I ran into it on a EST-2 that had been originally installed with no T-taps, and expanded with no T-taps. It wouldn't map and the only way I could get it to do so was to do some T-tapping.
                    I didn't understand it and neither did tech support.

                    I have installed a couple of these PITA Edwards systems. EST-2 product data specifically states no T-taps on the signature loop. Other systems use different terms for this circuit like polling loop, SLC circuit, IDnet. Every manufacture of addressable system gives a way to calculate the maximum circuit length for the reason that you stated. Voltage drop, impedance, and capacitance for shielded wire all play into the calculation. Could have been that the wire size that you were working with was too small for the length of the circuit.

                    1N73LL1G3NC3 15 7H3 4BILI7Y 70 4D4P7 70 CH4NG3.

                    Comment


                      #11
                      Originally posted by luckylerado View Post
                      I have installed a couple of these PITA Edwards systems. EST-2 product data specifically states no T-taps on the signature loop. Other systems use different terms for this circuit like polling loop, SLC circuit, IDnet. Every manufacture of addressable system gives a way to calculate the maximum circuit length for the reason that you stated. Voltage drop, impedance, and capacitance for shielded wire all play into the calculation. Could have been that the wire size that you were working with was too small for the length of the circuit.
                      It's been over 15 years since I worked on a EST-2, but no T-taps on a SIGA loop? Wow! Haven't seen literature or instructions in years, but wonder if what you read might have been for the Horn/Strobe loops or the device side of input modules?

                      I don't remember many specifics, but both the original system or the expansion were small (30-40 points after expansion?). EST tech support took me through all the wire posibilities again. It may have been a shot in the dark when they suggested I connect just the expanded area. Removing the original devices from programming allowed the panel to map, so I loaded the full program again, T-tapped the original devices in and it mapped perfectly. There was no joy about pulling wire for a permanent T-tap, but they wanted a final. The old guy came through again.

                      Comment


                        #12
                        T-taps are forbidden by my state's fire alarm code.

                        Comment


                          #13
                          Originally posted by GrayHair View Post
                          I'm afraid you are incorrect. I ran into it on a EST-2 that had been originally installed with no T-taps, and expanded with no T-taps. It wouldn't map and the only way I could get it to do so was to do some T-tapping.
                          I didn't understand it and neither did tech support.

                          A thank you to Luckylerado for a helpful response.

                          We will start off assuming a data circuit clear of both ground faults and corrosion (said corrosion can occur in existing circuits that have been exposed to a leak). To be fair, the EST2 manuals are internally inconsistent, i.e. it states "No 'T'-taps allowed", but shows examples of maps that have numerous actual or virtual 'T'-taps. Having said that, the statement "No 'T' taps allowed" as a manufacturer's requirement trumps any diagram or graphic in said document.

                          1. Did you ensure that both detectors and devices were wired correctly (i.e. feed from the panel to the 'in' terminals, feed to the next device from the 'out terminals) in the portion of the circuit being added?

                          2. Were wire distance calculations performed based on the wire type and gauge of both existing and new portions of your data loop? Did you count the number of SIGA-UM modules in both existing and new portions of your data loop, and consult the tables in the EST2 Wiring Practices Manual to check to ensure that your total circuit length is shorter than allowed? A close reading of these tables shows that you can load a data loop with SIGA-UMs to such an extent that your total allowable circuit length is 26'.

                          3. Replace any SIGA-IB detector bases on the existing portion of the data loop with SIGA-SB type bases. If your loop now maps, put the SIGA-IB bases back in one at a time, mapping the loop each time. At the point the loop won't map, throw that last SIGA-IB out, & install a new one.

                          4. Obtain a SIGA-MFT, aka a map fault tool. Disconnect the data loop from the EST2, hook it up to the MFT and run several tests. I run the tests 3 or 4 times, and change any device(s) that show up faulty multiple times.


                          Based on you creating a 'T'-tap that allowed the system to map, I think that your problem fell under item #2. It's physics, not magic.
                          In battle, in forest, at the precipice in the mountains,
                          On the dark great sea, in the midst of javelins and arrows,
                          In sleep, in confusion, in the depths of shame,
                          The good deeds a man has done before defend him.
                          --Bhagavad-Gita

                          Comment


                            #14
                            [COLOR=#0000cd]MichaelGP3[/COLOR]

                            My example was long ago; 15 to 20 years.

                            Comment

                            Working...
                            X