From: ehsjr@verizon.net   
      
   On 2/8/2026 1:03 PM, Don Y wrote:   
   > On 2/8/2026 10:47 AM, ehsjr wrote:   
   >> On 2/8/2026 12:05 PM, Don Y wrote:   
   >>> I am using devices like this:   
   >>>    
   >>> as volt-free interfaces to the signalling from smoke and CO detectors.   
   >>>   
   >>> The mains connections are visible (BK/WH).  The balance are   
   >>> connections to   
   >>> the isolated form C contacts, the "signal" wire from the detector(s)   
   >>> and a nominal 9VDC supply (that I would like to avoid using).   
   >>>   
   >>> First question:  does the "device" count as a regular "device" in   
   >>> terms of volume computations?   
   >>>   
   >>> Also, there are separation requirements from the mains when sharing a   
   >>> box.   
   >>> Aside from a split enclosure, I can't see how you can guarantee that   
   >>> given the rats nest you find in most boxes!   
   >>>   
   >>> Second question:  how would such a device typically be deployed to   
   >>> satisfy those requirements (the documentation accompanying it is   
   >>> ridiculously sparse).   
   >>>   
   >>> Third question:  if I use the contact to deliver mains voltage to   
   >>> something   
   >>> like a small indicator (forfeiting the galvanic isolation) and optically   
   >>> couple that state across the boundaries of the enclosure, what can you   
   >>> recommend (*listed*!) inside the box?   
   >>   
   >> If the thing in the picture is not a listed device   
   >> (per the NEC meaning of "listed") then you cannot   
   >> use it as part of the facility wiring and consider   
   >> it NEC compliant. Volume computation doesn't come   
   >> into it if the device is non-compliant.   
   >   
   > The devices are listed.  I deliberately avoided the temptation to   
   > design my own interface to the signal lead.   
   >   
   > But, that still doesn't tell me if it is considered as a "device"   
   > in the same sense that a light switch, receptacle, etc. would be   
   > in volume calculations.   
      
   For volume calculations you need to look at NEC section 314.16   
   I can't tell for sure how many conductors are in the picture,   
   nor can I tell their size or the number of conductors of conductors   
   entering the box.   
      
   Whether compliant for installation where planned or not would be   
   determined by the AHJ during the electrical plan review phase.  Not   
   all jurisdictions follow the NEC. (For exanmple, NYC has its own   
   code) There can be local rules more stringent than the NEC. That   
   said for NEC compliance section 314.16 applies.   
      
   >   
   >> If you're wondering about the UL224 marking, it's   
   >> for the heatshrink, not whatever is inside.   
   >>   
   >> Question 2:  dunno.   
   >>   
   >> Question 3:  Either get it listed, operate it under   
   >> "engineering supervision" acceptable to the AHJ   
   >> (electrical inspector at the usage location), or   
   >> build it into an appliance that is not part of the   
   >> facility wiring.  I'm sure you don't want any of   
   >> that; I don't know how else to do it. Sorry.   
   >   
   > I figured a mains powered lamp, visible through the   
   > Jbox, wouldn't raise any eyebrows "electrically".   
      
   If you modify the box to make the lamp visible, that's   
   a violation.  The NEC says you must follow manufacturers   
   instructions for installation and use of equipment.   
   There may be some kind of listed "indicator" junction box   
   that suits your specific needs - I dunno.   
      
   >   
   > But, then have to consider how *that* is interpreted   
   > in volume calculations.   
   >   
      
   Well, if willing, your local AHJ can assist you.  The   
   bottom line with "code compliance" is getting the local   
   AHJ's approval.   
      
   Ed   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)