In the panels manual(SFP-5UD) it says for the NACS and the initiating devices it says use untwisted, unshielded wire. Could you use shielded wire because in the whole chart it does not specify a specific use for shielded wire, so then what is it used for?
(In addition)
Or is this just a guide line so you don’t use shielded wire as you go to wire. Also if you can not use it, what would you use shielded wire for.
Shielded wire is typically used to keep RF out on wire used for data on addressable fire alarm systems, especially on older systems & where all the cables are run in the same raceway. The shield should be spliced through & safed off at each device and only grounded at the control panel. If the shield is grounded in two places, it can act like a radio antenna and cause all kinds of problems.
For instance, let’s say you have an addressable detection loop, 70V speaker circuit & a strobe circuit or two in the same conduit. If the data cable is unshielded, noise from the notification appliances can interfere with the data transmission on some systems when the speakers/strobes activate or turn off.
Note that if you use shielded cable capacitance is added to the circuit which can cause issues as well.
Shielded cable will probably work fine on a conventional panel or if you are doing something on a bench but if it’s for an occupied building or a live system, you may want to refer to the manufacturer to cover yourself.
Could I insulate each end of the wire at both the device and panel end to eliminate any connection to ground. Like with tape or heat shrink tubing. Wouldn’t this then eliminate the shield? (Conventional panel)
a lot of older panels used shielded wire, i’m sure some probably still do but for the most part i think a lot of manufacturers have gotten away from it.
Ok, so it is ok to insulate the ends instead?
You’ll probably be okay if this is in an existing building where you are using existing shielded wire or replacing the panel, etc.
I’d at least recommend you put something in writing to the building owner or his/her rep saying the manufacturer’s installation instructions state to use unshielded cable to cover yourself in the event it does cause problems. This way they can’t say you didn’t tell them and you did your due diligence.
okay, thanks