They may be safe but, if there is a failure when it is concealed in the ceiling with no access other than ripping everything open I think there is a problem.
You can't plaster over a junction box so what makes these things so special ?
I have to approve the installation but, some day in the future somebody is going to be blistering my ears about them spending half a day trying to find that open circuit.
At least an access plate so someone has a clue about where to look.
Alan--
NEC 90.1 Compliance...not necessarily efficient, convienient...etc.
