Non-incendive circuits

[scirocco_torc]

Could someone please clarify the definition of a non-incendive circuit in 500.2 (Definitions) for me:

A circuit, other than field wiring, in which any arc or thermal effect produced under intended operating conditions of the equipment is not capable, under specified test conditions, of igniting the flammable gas?air, vapor?air, or dust?air mixture.

Specifically, what do the words "other than field wiring" mean? Obviously they are excluding field wiring, but what not excluded? Is the component at the end of the field wiring (e.g a switch) "included" in the circuit? I would have thought so. I just can't quite grasp what the exclusion of the field wiring is trying to tell me.

Thanks.

 

[rbalex]

The ?short answer? is field wiring is any equipment or wiring not physically ??provided by the manufacturer of the intrinsically safe or associated apparatus, or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus...? i.e., something on the Control Drawing that is not provided by the manufacture.

The definition should be read in context of all the other ?nonincendive? definitions including Associated Nonincendive Field Wiring Apparatus and most importantly Control Drawing.