I'd treat Northwing's advice with extreme caution.
Although the main reason for avoiding HIRTAs within the published parameters is to avoid damage to electrical components within the aircraft, as a pilot, you can never be sure exactly what level of electrical or other radiation is being transmitted from the installation.
The height and radius of which the area should be avoided, indicates the maximum envelope to which harmful transmissions may extend, fly through it today and nothing may happen, do it tommorrow and you may get your radios and your nuts fried.
Why other taking the risk? would you take the same gamble with traffic lights?