The ornamental design for a ropelightpedestal for a lamp, as shown and described.
FIG. 1 is a front perspective view showing an embodiment of our new design;
FIG. 2 is a right side elevational view thereof, the left side being a mirror image;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a top plan view with the lamp head removed; and,
FIG. 5 is a bottom plan view.
The broken line showing of hardware (e.g., the switch, the gooseneck, the lampshade and light fixture) as well as the position of the hardware relative to the claimed design and any other broken lines are to show the environment only and are not part of the claimed design.