Class 1 Div 2 Junction Boxes

I am working on a Class I Div 2 application with instrumentation/sensor wiring. All devices are 24VDC or 4-20ma It is my understanding that:
  • Any devices with contacts that can arc (pushbuttons, solenoids) will be explosionproof and have a explosionproof seal at the device end of the conduit.
  • Any junction boxes without active devices (terminals only) can be NEMA 4 or 4X.

A couple of wrinkles:
  • For a XP device going to a junction box, is a second seal required at the junction box end of the conduit? It doesn't appear to be but would seem to be useful to prevent migration.
  • Is a NEMA 4/4X enclosure still acceptable if a NAMUR interface module (rated CL I Div 2) is installed?


Staff member
Question 1. No. There is no benefit sealing a non-explosionproof enclosure. See Section 501.15(B)(1). The key word is required.

Question 2. If the device is suitable for Division 2, see Section 501.105.