intrinsic safe circuit in crane festoon with power wire

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Rgandy85

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Salt lake city, Ut
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Overhead crane design
504.30(A)(1)

Exception No. 2: Where either (1) all of the intrinsically
safe circuit conductors or (2) all of the nonintrinsically safe
circuit conductors are in grounded metal-sheathed or
metal-clad cables where the sheathing or cladding is capable
of carrying fault current to ground.

I would like to run the intrinsic circuits in a shielded cable. If my power cable is fed from 60a OCPD would the shield on the intrinsic cable have to be rated for 60a?
 
Rgandy85 said:
504.30(A)(1)

Exception No. 2: Where either (1) all of the intrinsically
safe circuit conductors or (2) all of the nonintrinsically safe
circuit conductors are in grounded metal-sheathed or
metal-clad cables where the sheathing or cladding is capable
of carrying fault current to ground.

I would like to run the intrinsic circuits in a shielded cable. If my power cable is fed from 60a OCPD would the shield on the intrinsic cable have to be rated for 60a?
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No, it must be capable of carrying fault current (short-circuit or ground-fault) without additional damage until the fault is cleared. This will usually be much higher than 60A. A simple shield won't do. This basically envisions Type MI or MC cable. See the 2023 NEC where the Exception is removed and replaced with positive text.

You also need to be careful (VERY careful) with your overall grounding/bonding system. (Sections 501.30, 504.50, and 504.60) NOTE: I added, Section 501.30 to the list because any arcing fault in a Division 1, location is a likely (not just potential) explosion ignition source.
 
I should add Intrinsic Safety is not nearly the engineering/design/installation panacea some think it is. Grounding/Bonding/Boundary Sealing is virtually unchanged from "classic" hazardous location wiring methods. Securing and applying a proper control drawing can be difficult-without it you may as well use Division 1 wiring methods (or 2 if that's the real location's classification).
 
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