A Repair Station Owner reported an aircraft was destroyed by fire during a defuel operation.

Narrative

I own and operate a FAA repair station. I was performing an annual on a Cessna P210. The left hand fuel drain for the header tank under the pilots flooring had been dripping. I was able to remove the faulty quick drain with the fuel valve in the off position. I noted fuel continued to flow into the bucket as I inserted a plug to stop the flow. I realized that I needed to defuel the left hand wing to chase the threads of the header tank and repair or replace the faulty valve. I placed another bucket on a ladder under the left hand wing tank. I removed the wing drain safety wire. I pushed over the defuel pallet container that the buckets of fuel would later be poured into. I decided to remove the wing drain valve and begin filling the bucket while I went to get a jumper cable to ground the defueling pallet to the aircraft. In that moment I reached over to set the wrench and removed valve on the defuel pallet container to free my hands to go get the jumper cables. A fire ball/explosion occurred. I ran to get a fire extinguisher; it did suppress the flames below the aircraft/wing but the stream of ignited fuel pouring out of the wing draining continued to reignite as what ever I had contained. When the extinguisher was empty there was a secondary fireball and I left the shop. The hanger door was open (about 4-5 foot; Bifold type door) to the north with airflow coming in. As I exited the hanger I hit the 'open' door to raise it up. Fire department arrive extinguished fire. Aircraft was a total lost. Hanger severely damaged. I had minor injuries/burns. In reflection of this event. The day was a windy day; static discharge seemed more likely. I began fueling into the bucket as described before grounding the defueling pallet to the aircraft. I am questioning it that would have prevented this explosion because the fuel was not being poured in the defuel pallet. I have never grounded a bucket in 43 years of aircraft maintenance; but consider it would be wise. I am under the belief that a shop should have a 6 foot copper grounding rod connected to a grounding cable as a main ground. As a FAA CRS I have never been asked if I had one; nor discussed if it is required feature to shop defuel ops. Bonding the bucket(s); aircraft; defuel pallet; ground rod; And the defuel person really seems like the safest way in higher static environments that are out of your control. The following be done before any fuel work as judgment and situation dictate.