A tank for a circuit breaker has a body defining an interior volume and having opposing ends. An flange is at each end of the body with the flanges defining a central longitudinal axis of the body. The body has an internal surface defining a top portion of the tank disposed substantially above the axis and defining a bottom portion of the tank disposed substantially below the axis. The top portion is spaced from the axis as defined by at least a first radius from the axis. The bottom portion is spaced from the axis as defined by at least a second radius from axis. The second radius is greater than the first radius so as to reduce an electric field intensity on the bottom portion of the body and thus reduce effects of foreign particles within the interior volume, regardless of phase rotation.