Electric water heater with improved insulation structure

The external jacket structure of an electric water heater defines with the water storage tank portion thereof a hollow insulation space that horizontally circumscribes and extends across the top end of the tank. A fiberglass foam stop block member is pressed between the tank and jacket and has a cutout area through which an immersion heating element end connector is exposed to a first jacket sidewall opening normally covered by a removable access panel. A control panel mounted externally on the jacket above the first jacket sidewall opening has a bottom interior portion that downwardly overlaps a top portion of the cutout area and communicates therewith through a second jacket opening. An electrical control component disposed in an upper interior portion of the control panel is operatively connected to the heating element end connector by electrical wiring extending from the control component sequentially through the control panel interior, inwardly through the second jacket sidewall opening, and through the foam stop block member cutout area. The hollow insulation space between the tank and jacket is filled with a hardened foam insulation material injected into the insulation space through the jacket at a point thereon disposed outwardly of the exterior edge periphery of the foam stop block member.