We are working on a project where there are many remote devices reporting back to a SCADA system. They are devises such as float switches, pressure transducers, pressure switches, control panel signals visa dry contacts etc. The wiring is either individual conductor like 2-#18 or shielded twisted pair. The signaling power will be 24VDC. I am trying to classify this wiring and suspect it falls under section 725 of the NEC and am looking for some assistance. I need to figure this out in order to figure out how many conductors/cables can be in the same conduit.
wiring classification for devices to SCADA
- Thread starter mjmike
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
why would it matter any? none of them are current carrying conductors.
Just as an example, the derating factors of 310-15.b.2.a apply in some cases.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
most of these circuits are going to have currents measured in milliamps. I just do not see any derating being an issue at all. there just is no heat that will be generated in these conductors.
I understand that. The power supply itself is only 100w. However, I would still like to be able to know how to go about classifying the wiring.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
if it is a 100W power supply it might well be a class 2 power supply.
I researched the power supply and the manufacturer noted it is not a listed class 2 or class 3 power supply so I think that then means the wiring will be class 1 even though it is only 24VDC.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
that would appear to be the case then.
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