The ornamental design for a cablespliceprotectionbox, as shown and described.
FIG. 1 illustrates an end view of a cable splice protection box showing my new design. It is understood that the box has thin walls, with both ends are open, and the opposite end being the same as the end view shown;
FIG. 2 illustrates a side elevation view thereof; and,
FIG. 3 illustrates a top plan view thereof.
The surface(s) or portion(s) of the article not shown in the drawings or shown in dashed lines are unclaimed subject matter and form no part of the claimed design.