St. Michael's Church located in the Old Town neighborhood on the near north side in chicago has a very tall clock/ bell tower and a smaller chapel structure both currently being protected by a UL classified lightning protection system with a master label. there are air terminals using typical franklin copper air terminal grounding rods at the main ridge of the sanctuary roof and connected by copper braided cable up multiple sides of the masonry structure to the top of cross at the clock/ bell tower steeple which is approximately 286 ft high and other portions of the church and rectory structure with multiple leads and grounds etc. a smaller connected chapel structure only 50 ft high to the gable ridge is within 100 ft horizontally at the ground plane.
a massive lightning bolt and fireball was visually seen by numerous people in the local neighborhood to hit the top of the clock/bell tower at the cross and upper ornamental metal surround . the pastor was in his office in the rectory at the time and said the lightning was so bright at the time of the incident that it lit his office brightly thru a large window facing the chapel and courtyard during the darkened sky of a late afternoon thunderstorm. the same lightning strike also hit an unprotected corner stone of the bell tower structure building at approximately 120 ft in elevation and caused large multiple stone spalls to fall to the ground. a single 30 inch tall stone cross at the peak of the end gable of the chapel was also hit and caused the stone cross to break and fall where it was found dangling by the attached copper ground cable and what remained of the copper air terminal rod that had been attached .
luckily no damage or passerbys were injured; the fire department responded to multiple calls , and went to the top of the wooden steeple structure to inspect and verifiy that there was no fire at the heavy timber wood steeple structure. the copper air terminals were inspected and replaced during a subsequent renovation and exterior restoration. many additional air terminals were added to achieve the UL certification. some of the older air terminals at various areas showed signs of multiple hits and few were melted down considerably.
i think the old grounding method works rather well given these observed results don leone, jr. - architect, chicago Reply to this comment |