? about control and instrumentation wiring

[jessewi]

1-what is the difference between control wiring and instrumentation wiring?

2-conduit fill for control wiring, can you fill conduit to 60%, do you have to derate for current carring conductors?

3-can conduit containing instrumnetation wiring be filled to 60%?

4-cable tray containing instrumentation wiring, can data, speaker, fire alarm, fiber obtic, low voltage switching cabling be installed in the same tray without any trouble?

 

[tom baker]

Re: ? about control and instrumentation wiring

1- The types of wiring are described in Art 725
Class 1 power limited -
Class 1 non power limited
Class 2
Class 3
Class 1 non power limited is a typical motor control circuit, fused
Class 2 is commonly PLC input and output wiring

Seperation is required, see 725.55

Raceway is not required for Class 2, Class 1 is a chapter 3 wiring method

The advantage of a class 1 motor control circuit is derating is not required if 10% of ampacity is not exceeded

 

[petersonra]

Re: ? about control and instrumentation wiring

Originally posted by jessewi:
1-what is the difference between control wiring and instrumentation wiring?

The code does not define either.

2-conduit fill for control wiring, can you fill conduit to 60%, do you have to derate for current carring conductors?

many times these type of conductors are not considered current carrying at all.

3-can conduit containing instrumnetation wiring be filled to 60%?

It would be pretty full if you did. Again, the code talks about class 1,2, and 3 circuits, not instrumentation wiring. You have to decide what type of circuit it is.

4-cable tray containing instrumentation wiring, can data, speaker, fire alarm, fiber obtic, low voltage switching cabling be installed in the same tray without any trouble?

Yes - but you may need to put some of them in a seperate raceway.

[ November 10, 2005, 08:08 AM: Message edited by: petersonra ]

 

[don_resqcapt19]

Re: ? about control and instrumentation wiring

There is not a clear cut wire fill rule for Article 725 installations. The rule that applies is 300.17.
Don

 

[steve66]

Re: ? about control and instrumentation wiring

2-conduit fill for control wiring, can you fill conduit to 60%, do you have to derate for current carring conductors?

310.15, Exception #1, of the 2002 NEC covers derating. It basically says derating only applies to power and lighting conductors. A commentary in the handbook says the exception assumes the heating from control and signal conductors will not be enough to significantly increase the temp. of teh power and lighting conductors.

Steve