Not sure, but they may have denied a claim to replace the motherboard because their "exclusion" clause says that any equipment with a microchip or a microprocessor is not covered.

Nice overview!

I don't understand why they say a class 2 is functionally better than class 1 for inside?

Geeking out for a minute... Electrically, they connect to the same point in the breaker box.

Class 1 is connected directly to the buss bar using 2ga wire.

Class 2 is connected to the buss bar through a circuit breaker using 14ga wire.

In respect to a high voltage transient, seems Class 1 should have a lower impedance path to ground?

You are thinking about power and voltage at Steady State which is not the case with a power surge.

When you get a power surge besides the over voltage level, the duration of the surge also varies. Many power surges are very fast, less than a millisecond or two so the length of wire between the circuit with the surge and the surge protector itself becomes significant. Because the Type-2 protector at the circuit breaker panel is the closest to all the branch circuits, it should catch almost all the power surges. The Type-1 surge protector at the meter, in relative terms, is too far from the origin of the surge if it doesn't originate from the power lines outside the house and won't catch it. If the surge duration was long then you are correct the Type-1 at the meter would have an effect in clamping the over voltage.

When you read the Eaton Ultra installation instructions, Eaton wants the surge protector to have the shortest wire length to the connection points inside your circuit breaker panel for this reason.

Good for you installing a surge protector on the A/C unit power disconnect outside. You can also install that type of surge protector on the power disconnect at you pool and hot tub. These are called Type-2 protectors and one popular one is made by Intermatic. I also have an Intermatic Surge protector installed at my HVAC and Hot Tub power disconnects. More layers, More protection.

Amazon.com

Understood, true for installations where the wire from the meter to the box is typically several feet long.

But here (at least current installations), the wire from the meter runs directly through the garage wall into the breaker box and is very short so probably not a significant difference.

Do we probably also need one for the mini-split?

Thanks!

Our last house had a surge protector installed in the breaker panel. I don't know if it ever protected us from a big surge like a nearby lightning strike but I did notice the light bulbs in the house seemed to last forever. Perhaps it was stopping all the little spikes that nibble away at things.

That would be wise.

Compressors/pumps put transients back on the power line, especially during start up, so at least in theory, a suppressor at the unit reduces these spikes making it back to the rest of the house.

Most mini-splits already have a surge protector. Look at the power disconnect and see if there is a box with a green light on it. If not, absolutely get one asap as the control circuitry can be damaged by surges.