Wire Supervision/ t-tapping

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akbrtrdr

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Seems like i read in the code at some point there are instances where alarm wiring does not need to be supervised such as a run under 3 feet long. I was also told by an engineer t-tapping on a conventional system is allowed if the device being tapped is within 5' of the tap. Can anyone confirm or dispute this?
Thanks
 
akbrtrdr said:
Seems like i read in the code at some point there are instances where alarm wiring does not need to be supervised such as a run under 3 feet long. I was also told by an engineer t-tapping on a conventional system is allowed if the device being tapped is within 5' of the tap. Can anyone confirm or dispute this?
Thanks
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The 3-foot rule is generally for the location of a control or relay module used for interacting with 3rd party systems such as fire/smoke dampers and elevator controllers. This is because usually the dry contact output is unsupervised, so the code folks said 3 feet was close enough. Per NFPA 72-2016:

21.2.4* Emergency control function interface devices shall be
located within 3 ft (1 m) of the component controlling the
emergency control function.

For T-taps, there is no slack as far as conventional systems are concerned. If you T-tap, which ever branch doesn't contain a resistor is not supervised. There is one conventional panel I've run into that allows you to T-tap, once. It was the FCI-72, IIRC.
 
gadfly56 said:
The 3-foot rule is generally for the location of a control or relay module used for interacting with 3rd party systems such as fire/smoke dampers and elevator controllers. This is because usually the dry contact output is unsupervised, so the code folks said 3 feet was close enough. Per NFPA 72-2016:

21.2.4* Emergency control function interface devices shall be
located within 3 ft (1 m) of the component controlling the
emergency control function.

For T-taps, there is no slack as far as conventional systems are concerned. If you T-tap, which ever branch doesn't contain a resistor is not supervised. There is one conventional panel I've run into that allows you to T-tap, once. It was the FCI-72, IIRC.
Click to expand...

Doesn't matter if the branch is 1 foot or 1000 feet long either.

I don't work on this kind of thing hardly at all, but would think addressable components can possibly change the rules a little. If an addressed object stops communicating it can cause a trouble alert.
 
kwired said:
Doesn't matter if the branch is 1 foot or 1000 feet long either.

I don't work on this kind of thing hardly at all, but would think addressable components can possibly change the rules a little. If an addressed object stops communicating it can cause a trouble alert.
Click to expand...
Yes, that is true. For Class B systems, the signal line circuit (SLC) may be T-tapped. However, for Class A SLC's and all notification appliance circuits, T-tapping is not allowed.
 
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