From: blockedofcourse@foo.invalid   
      
   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.   
      
   > 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".   
      
   But, then have to consider how *that* is interpreted   
   in volume calculations.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)