mstrlucky74
Senior Member
- Location
- NJ
What takes place when you t tap? Thanks.
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).
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.
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.
..... Some addressable systems (EST) need to be T-tapped to operate properly.
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.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.
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 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.
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.