Since I first saw these, I have thought that they are probably only approved for use in a luminaire where conductors or similar environment like a junction box where wires may be joined with wire nuts or similar methods. Recently, I saw a connector like this, in a factory-packaged LED retrofit for can light lamp retrofit. It is between the adaptor for the Edison Socket and the lamp leads which puts it in the cavity where the incandescent lamp used to be. That is not exactly an area where one finds wire splices as part of the original intent for the luminaire.
Can anyone tell me where they are approved to be used? I suppose use in a retrofit kit falls under UL and not NEC so the manufacturer can take an OTC device, use it differently and apply for approval as part of a device like this, but I wonder if there is more of a range of use for the connecter than I thought.
FYI, I found this interesting product for conduit just now when surfing around a little:
Here is a link that might be useful: luminaire disco