Switch box in contact with 1-inch clearance B-vent flue

[SCBO1]

Doing a rough-in inspection and came across a white switch box making contact with a B-vent flue. First thought was you can't do that! So I have been trying to find if it is permitted?

The 1-inch clearance for the B-vent flue is to combustibles. If this box was non-metallic or Bakelite would it be allowed to touch the flue?

What about if the box was PVC? I would think this would not be allowed.

 

[Paul Sweet]

The NEC would probably require high-temperature insulation on conductors and possibly oversizing the conductors for a high ambient temperature.

Hopefully the manufacturers instructions require separation from B-vents and other high temperature items.

 

[SCBO1]

Allied Moulded #434 Fiberglas switch box touching a 1-inch clearance B-vent.

• Standards:
  ANSI / UL 514C: File No. E30594
  
  
  

• Fire Classification:
  Fire Test of Building Construction Materials
  ANSI / UL 263: File No. CEYY.R9379 (Category / File No.)
  
  Note: Products must also be certified to: ANSI / UL 514C
  
  Fire Resistance Classification in Wall Assemblies 2-Hours or less
  Shall be separated by a horizontal distance of not less than 24 inches
  
  Note: For more details please refer to the UL fire resistive directory and Allied Moulded’s CEYY.9379 (Outlet boxes and fittings classified for fire resistance)