Why surge protectors dont protect against a lightning strike

One of the miths of the modern days is that a surge protector or a UPS will provide sufficient protection against lightning strikes (not 100%, but close enough), including a direct one (a lightning strike to your home or office building). Well... you should not put much hope on it.

The surge protectors have some limits, every time when the values of the voltage and the amperage on the lines are less the minimum or greater than the maximum limit the electronics and electrical appliances will suffer damages or they will be destroyed. It does not need to appear smoke out of the back of an electronic device in order to stop functioning... power fluctuations are as destructive as the lightning strike. And most of all, they happen a lot often the the lightning (from the average consumer point of view).

A common surge protector will stop most of the voltage spikes and surges (the most power fluctuations), but it does not have a chance against the violent catastrophic burst of current from a close or direct lightning strike. In order to provide 100% protection any system must divert almost 100% of the lightning current from a direct strike, which is nearly physically impossible. The value of the current is too big to protect with a little electronic device inside a power strip, or even an UPS unit. If your UPS or surge protector is in the way of the lightning's path it will just flash over or through the device, regardless of the amount of battery banks and capacitors involved.

Even more: the current have the property to "jump" over a gap when there is no ressitance. That means that the current can pass the switched off contacts and power up (than burst into flame) almost any turned off device in its path. From this point of view the lightning is merely the visible path (the plasma) of the current that jumps across many kilometers of air from one point to another... so don't assume that it won't jump several centimeters more through some contacts, the surge protectors and your devices on a direct strike.

Lightning current often peaks at 100,000 or more Amperes. Remeber this when you consider that you have a lightning protection system installed and your house could be hit directly by lightning. If the protection system takes even 99.9% of the current, then your electrical wiring may take the remaining 0.1%. Are you good at math?  0.1% of 100,000 Amperes is a 100 Amp surge through your wires and phone lines, a value that may be enough to take out your electronic devices and your home appliances.

That's why it's important to remember that in severe storms the best protections is to unplug all your home electrical appliances and disconnect the cable and phone lines.