The ornamental design for a housing for a transformer, as shown and described.
FIG. 1 is a top, front and left side perspective view of a housing for a
transformer showing our new design;
FIG. 2 is a rear side elevational view thereof;
FIG. 3 is a right side elevational view thereof, the right side elevational
view thereof being a mirror image of the left side elevational view
thereof; and,
FIG. 4 is a bottom side plan view thereof.
The broken line matter in all figures is for illustrative purposes only and
forms no part of the claimed design.