[onelasttry]

Which is the best protection for a computer from lightning: to uplug the surge protector for the computer from the wall... or to just flip the switch on the surge protector to OFF?

[KISS]

Unplugged.

[seahwk83]

Agree with above

[Dont treadonme]

NEITHER

A surge protector does NOT protect your expensive computer from much of anything

You need an APC SMART UPS

[KISS]

NEITHER

a surge protector does NOT protect your expensive computer from much of anything

you need an APC SMART UPS

You got this disagree because you imply that a smart UPS will protect against lightning. If the power line sustainined a direct hit and the sensitive equipment was connected, your only chance of protection would be a whole house Transient Voltage Suppression System. This has the lowest ground resistance to dissipate the surge.

Computers/servers also connect to different areas of the same building. Lightning can change the grounds potentials even within a single building over a few hundred feet. Fiber optic connections can lessen effect from lightning induced ground potential changes.

I couldn't even figure out if the Smart UPS was an always on technology based on the data sheets. APC looks as if they gave a selection matrix

If an EMP (Electromagnetic Pulse) were present and the computer was unplugged, it may survive (don't forget the battery backup clock circuits). That's far worse than lightning.

I've seen an ISOBAR surge protector blow up, $50,000 warranty from a hit. The connected equipment was damaged too. Unplugged would have been better.

Protection needs to be "SELECTED". After adding a particular device, I got 25-30 years protection to computers. The only failures were mechanical and even the disk drive in one was still running after 14 years. The computer wasn't used 24/7, but was on during the workday and off during the weekends and expected storms. Blackouts, in general were rare.

One single-phasing event took out a lot of motors. A generator was required in our applications for some loads, most of which were ventillation. One piece of equipment would require about 8 hours to restart, if we lost power for more than about 10 minutes.

The SMART UPS seems to be a good technology, but not designed to protect against lightning. Lightning rods on a building would be a good start. A whole house TVSSS would be secondary and an examination of what's connected to the outside world.

I had a retrofitted computer controlled x-ray set that would take out it's controller in the system arced (100 KV power supply). Optically isolating, ~$70, the communications link to the computer fixed that problem.