When dealing with Obsolete Electrical Gear its wise to use a Chicken Switch

all thats left of insulators on single phase transformer

Recently at one of my  Industrial customers who recycle oil they suffered a lightning strike which damaged  some of the electrical gear . At the front of the building a lightning strike took out and destroyed a pole mounted Transformer killing the 230/120 volt lighting circuit to the plant. Luckily a generator kept things working and there was little damage because I had installed whole panel surge protectors on most of the panels the one I had not gotten to in the lunch room they lost a microwave oven and the old fuse panel was damaged. It will soon be replaced with a breaker panel insert and surge protector put into it .

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Damaged lunch room fuse panel

After the power company came and restored power at 9:30 Pm  I walked thru plant checking everything and other than tripped surge protectors  everything was working  I reset the surge protectors and thats when I noticed the Three Phase 480 volt Delta system was not restored at that late hour I was not going to call Duquesne Light  Power Company workers   back in plant and manager said he would call them back in morning out of safety concerns.
Morning came and I meet up with Duquesne Light Workers at back of the plant they had tested the 5000 KVA  32,000 to 480 Delta to delta Transformer which provides 1200 amps of 480 3 phase power to the plant  and all 3 fuses where out . They replaced the fuses in this very old transformer from when this plant originally made Steel drums and barrels   and where worried about turning it back on the switch to control it was located with in the sheet metal enclosure they asked for a hole saw so they could cut a hole and run a rope to outside so they could pull the switch from a safe distance away . What they made is whats commonly known as a chicken switch it allows potentially dangerous items to be turned on from a safe distance. If you watch the TV program " Sons of Guns " on the Discovery Channel  when they test big guns and cannons first time its the same ideal.

Well they setup the rope worried over how old this transformer was possibly bad since all 3 fuses blew and good thing they did after pulling the rope there was a tremendous loud explosion and big blue flash and smoke  followed by a second one 20 seconds later. 40 foot away I was nearly knocked off my feet . The blast was so strong it damaged nearby freon lines for an HVAC unit even if the utility workers had on a blast suit made for working around high voltage they would have been seriously injured had they stayed with in the enclosure surprisingly the heavy steel casing of the transformer did not blow apart but  the rear 480 volt secondary insulators on back where blown apart.
In this case it was absolutely the right call to use a chicken switch or some one could have died very easily. After the blast the power company workers went to work quickly to replace the transformer but did not have an immediate back up replacement so they brought in a back up replacement trailer which serves as a temporary transformer

Portable Transformer

and with in 12 hours power was restored . During turning the 3 phase back on and inspecting things I found a 200 amp distribution switch off the buss severally damaged I was temporarily able to get it working again and will be replacing it shortly when a new unit is located and a compressor was damaged. needless to say seeing how el the surge protectors worked in the rest of the plant they  want me to install surge suppression all over the 480- 3 phase system to protect it from future issues.

Damaged compressor control