Mounting rail for a lamp

1. In combination:

a generally U-section adapter profile extending along a longitudinal axis, forming a longitudinally extending and transversely open cavity and having an outer surface formed with an array of at least three longitudinally extending and radially outwardly directed outer mounting formations radially spaced from the longitudinal axis and angularly spaced around the longitudinal axis;

an elongated light emitter in the cavity; and

a generally U-section mounting rail extending parallel to the axis, open radially toward the axis, and having two side walls formed with inwardly directed and longitudinally extending inner mounting formations generally complementary to the outer formations and spaced so that the profile can be fitted to the rail in at least two different positions in each of which the two inner formations of the rail engage in two of the outer formations of the profile.

2. The combination defined in claim 1 wherein the adapter profile has an inner mounting face on which the light emitter is mounted.

3. The combination defined in claim 2 wherein the light emitter is a LED strip.

4. The combination defined in claim 3 wherein the mounting face is formed with a pair of longitudinally extending guide grooves that transversely flank the LED strip.

5. The combination defined in claim 2 wherein the mounting face is substantially planar and parallel to the axis and the emitter is directed diametrally of the axis out of the cavity.

6. The combination defined in claim 2 wherein the adapter has a pair of inner faces symmetrically flanking the mounting face.

7. The combination defined in claim 6 wherein the inner faces diverge away from the mounting face.

8. The combination defined in claim 7 wherein each of the inner faces is formed adjacent the mounting face with a respective inwardly open groove.

9. The combination defined in claim 1 , further comprising

a mass of at least translucent material filling the cavity.

10. The combination defined in claim 1 wherein the outer mounting formations are radially equispaced from the axis.

11. The combination defined in claim 10 wherein there at least two pairs of the outer formations and the formations of the pairs are at the same transverse spacing from each other, the inner formations being at a transverse spacing equal to or slightly less than the transverse spacing of the pairs, whereby in each of the position the outer formations of a respective one of the pairs are engaged with the inner formations.

12. The combination defined in claim 11 wherein there are three such pairs of the outer formations.

13. The combination defined in claim 1 wherein the outer formations are grooves of part-circular section and the inner formations are complementary ridges of part-circular section.

14. The combination defined in claim 1 wherein the adapter is of constant cross section.

15. The combination defined in claim 1 wherein the adapter outer surface is formed by flat outwardly directed faces extending between the outer formations.

16. The combination defined in claim 15 wherein the faces are planar.

17. The combination defined in claim 15 wherein one of the faces underlies the light emitter and is centrally formed with an outwardly open groove, the combination further comprising:

an electric supply cable extending in the groove.

18. The combination defined in claim 15 wherein the groove has a mouth of a width slightly smaller than a diameter of the cable.

19. The combination defined in claim 1 wherein the mounting rail has a pair of side walls having inner faces and outer edges and each formed on the respective inner face at the respective outer edge with the respective inner mounting formation.

20. The combination defined in claim 19 wherein the side walls converge toward each other at an angle of about 2°.