In the UK it seems pretty common to see junction boxes with built-in screw terminals that are used only for splicing wires from 2 or more cables together.
Sample wiring diagram:
[These particular links are just examples.]
Are these acceptable for use in the US? (assuming "typical" building codes which I know vary locally).
Given that the jbox is installed in an accessible location and used as per its specifications as to volts/amps, I'm not sure what other factors might determine if these could / could not be used?
Although standard US jboxes are versatile, an advantage of these UK style boxes is that they are quite compact and they assist in making what seem to be very secure connections. Also the round cover is cleverly designed to leave open only as many side 'ports' as there are cables entering; so no holes have to be punched nor covered. Its basically an all-in-one type product for the common splicing situations.
So I've always been surprised that (essentially) the same thing doesn't seem to be available here. They seem DIY-friendly in particular.
(That said, when I lived in the UK I recall many of these were cheap brittle plastic and had to be installed carefully to avoid breakage.)