control wiring

[mandon]

I have an install that the engineer wants to run 480v feeders to various pieces of equiptment and control wires for sensors through the same manhole he told me that you can do this as long as the cable is rated at the same voltage as the feeders I don't believe he is right based on art. 725, without installing a barrier of some sort. any insight would be appreciated.

 

[infinity]

Re: control wiring

If the control wires are part of a class 2 or class 3 system than they must be run separately from the line conductors. The insulation value has nothing to do with this limitation under Article 725.

 

[iwire]

Re: control wiring

Originally posted by infinity:
If the control wires are part of a class 2 or class 3 system than they must be run separately from the line conductors. The insulation value has nothing to do with this limitation under Article 725.

I agree with infinity, the rules of 725 make the allowance of 300.3(C)(1) unusable for the most part.

There is an exception in 725 that might help but IMO it would be easer and better to run separate raceways.

725.52 Exception No. 2: Class 2 and Class 3 circuits shall be permitted to be reclassified and installed as Class 1 circuits if the Class 2 and Class 3 markings required in 725.42 are eliminated and the entire circuit is installed using the wiring methods and materials in accordance with Part II, Class 1 circuits. Class 2 and Class 3 circuits reclassified and installed as Class 1 circuits shall not be classified as Class 2 or Class 3 circuits, regardless of the continued connection to a Class 2 or Class 3 power source.

 

[don_resqcapt19]

Re: control wiring

If they are just in the same manhole and not the same raceway or cable, then look at 722.55(F). This would not be too difficult to comply with.
Don

 

[redfish]

Re: control wiring

If they are just in the same manhole and not the same raceway or cable, then look at 722.55(F). This would not be too difficult to comply with.

Would that be 725.55 (F)?

 

[highkvoltage]

Re: control wiring

Mandon. Other than the code violations you may have to deal with that the other posters pointed out my question is what type of control wiring is it you are going to run? If it depends on a freqency signal and you may end up with a problem from the magnetic field from the feeders. Either way I agree with the others and would avoid this type of installation to many problems may occur.

[ August 21, 2005, 11:50 PM: Message edited by: highkvoltage ]