Lightning makes my saw blade move?

[Pat Barry]

Are you certain it moved? I mean, there was a lightening storm, lots of flashing light. If you were glancing around the shop and maybe just caught a reflection of the flash it might appear that the blade moved but it was just an illusion. But, for the sake of argument, lets say it actually did move due to an electrical surge, then why would it move back? Do you think there was a reverse surge to make it move back? Keep in mind its an AC motor, there would have to be some highly coincidental phase fields to make it do anything. I just doubt that it moved. Now if you were watching it and had your total attention on it while this storm was going on then I might be more inclined to believe it. Call it a mirage.

[Neil Brooks]

Whole-house surge protectors should only run about $150 to $250, depending on brand/features. Installation cost should be negligible because they install it when they wire the panel.

I'd find out what they're installing for $1000 to make sure you're getting your money's worth.

Thank you, Phil. A thousand things to research, and I did NOT look into that one.

I will, now, though

[Steve Ryan]

Magnetic field from strike induced current in the winding causing the slight movement. Had an aluminum shaft umbrella in my hand at an airfield, slight drizzle. Dark on the horizon as storm apprached. Saw a lightning strike quite a few miles away and at same time my thumb tickeled. Turned my eye to my thumb and saw another flash, and at the same time saw a spark jump from the shaft to my thumb, about a half inch away. Yeah, closed the umbrella and ran for my car.

[Dan Hintz]

Magnetic field from strike induced current in the winding causing the slight movement. Had an aluminum shaft umbrella in my hand at an airfield, slight drizzle. Dark on the horizon as storm apprached. Saw a lightning strike quite a few miles away and at same time my thumb tickeled. Turned my eye to my thumb and saw another flash, and at the same time saw a spark jump from the shaft to my thumb, about a half inch away. Yeah, closed the umbrella and ran for my car.

A straight, aluminum pole picking up an electric field strong enough to ionize air over half an inch? You have so many things working against you there for creating a spark, I'm surprised the lightning bolt didn't just strike you directly.

[Steve Ryan]

A straight, aluminum pole picking up an electric field strong enough to ionize air over half an inch? You have so many things working against you there for creating a spark, I'm surprised the lightning bolt didn't just strike you directly.

I knew the storm was coming and could hear the rumble long before any light show. I was standing on a de commisioned army airfield and could see the storm many many miles off in the distance. How many million volts in a lightning strike? Damp shoes and a plastic handle on the umbrella. A friend had a lightning arrestor on his TV antenna (inside his house) and there were often juicey sparks at the gap with lightning way off in the distance.
Funny thing is that we were auto racing, rain or shine. About 20 of us scattered around the area. Call came over the radio to come in and take cover in our cars. Pickup truck went out to pick the farther workers up. On an open aluminum car trailer! No thanks, ran to my car in the rain.

[Chris Tsutsui]

A couple of ideas from an average joe that works in the cathodic protection field.

I believe it's current related and probably not magnetic though it's difficult to say because I have one other theory.

If I were to hit a tablesaw with a hammer, there's a chance the blade can move the way the OP says, thus lightning can often give a home quite a shake so it could be "physical" movement of the saw blade if the belt has some torque/tension.

Belts have a memory so it is not uncommon for me to move a blade a little bit, and watch it go back to its original position. This explains the saw blade moving back to its original position. ON my old delta jointer I could literally turn the cutter 30 degrees and watch it go back to its original position.

Another theory is the tablesaw is plugged into a wall with no surge protector or supressor. Current goes everywhere during that lightning strike so I want to say a little bit of current caused a slight motor torque that came from the power cord plugged into the wall. It just takes a little current spike to jolt the induction motor ever so slightly. If one were to use a defibulator on a motor then I also imagine there could be slight movement of the armature.

If you had a surge protector to protect your home's main panel, then this is what's readily available to isolate our machines from lightning problem.

What can also save your machines is a lightning protection system that channels the lighting from a lightning rod, through thick wires running down the building into copper grounding rods/mesh in the ground.

[John McClanahan]

I'm thinking the flashes of lightening through the windows caused a shift in lighting and shadows, giving the illusion of movement. Pat Barry has good points on the effect of DC current on a AC motor.

John