How does article 400 apply to this? 411 Mentions nothing about splices whatsoever. Reference to accesible splices on low voltage systems? The correct wiring method was used in the wall. The system only operates at 12 volts. I see your point about wanting to see the splices but also the Ec was probably thinking he was doing a nice job for the homeowner by hiding the splices. Did you ask what he did? Are you comfortable with his work? If so I really don't see an issue here.
