Instrument JB’s depend upon hazards area classification.

JB’s also can be IS or NIS

For IS signal IS JB’s used for NIS signal NIS JB’s used

For analog I/p & o/p signal we can use same JB.

But for Digital I/p & o/p we have to use separate JB’s. Because digital outputs are powered signal, by wrong connection there may be chances to damage the card.

For DCS I/p & o/p and PLC I/p & o/p we used separate JB’s.