Originally posted by Daveman Deluxe
Surge protectors operate fundamentally differently from surge arrestors. Surge protectors are designed primarily for the spikes in power that occur when power comes back on after an outage or a brownout. There are a pair of contacts that separate and turn off the power when such a spike is detected, much in the same way a circuit breaker works, only much faster. Basically, it flips the switch. The problem is that a quarter-inch is nothing to hundreds of thousands of volts of electricity which just jumped two or three miles from the clouds to the ground.
A surge arrestor actually has a contact that will switch the load to the ground when a spike is detected. Since that is the easiest path for the electricity to take, the power will ground out through the ground pin on the electricity rather than through your iMac.