<p>A support bracket (1) for supporting insulating rods (2) inside an insulator tube (3) of a hollow core insulator. The support bracket comprises a cylindrical ring (4) with an outer surface (5) for abutting against the inner surface (6) of an insulator tube, an inner surface (7) for supporting an insulating rod and two opposing end sides, here denominated first (8a) and second (8b) end sides. The support bracket comprises an expansion assembly having means configured to be actuated so as to expand the cylindrical ring in at least one radial direction when the support bracket has been inserted in an insulator tube of a live tank circuit breaker.</p>