Surge protectors

[El Greco]

There are a lot of sources that claim surge protectors can't protect from a lightning because there simply is too much current and the only way to effectively protect any device is to unplug it during storms. On the other hand, several manufacturers say that their protectors, when overloaded, will get damaged themselves but will cut the power to the devices and so it's effectively the same as unplugging them. And there is also the odd anecdotal report of people who say that after a lightning they lost many sensitive devices but those plugged in a surge protector survived. So what's the deal ? Is it possible to 100% protect from a lightning with a surge protector ?

 

[mike81]

It's my understanding that surge protectors are not really for protecting from a lightning strike. They are to protect from power surges that happen when doing things like turning on and off devices plugged into the circuit. The joule rating is the amount of surges that the device can absorb over it's lifetime before no longer working.

 

[ceptimus]

Surge protectors can protect your devices to a certain extent - say lightning strikes the ground 100 yards from your house.

If you get a direct strike to your house then your connected devices are likely to be toast, whether or not they have surge protectors. Even disconnected devices are likely to be destroyed in the unlikely event that lightning hits them.

Lightning takes strange unpredictable paths though.

 

[Apathia]

During any given electric storm, my grandmother would have my sister and I unplug all the appliances and huddle in the center of the house. We wanted to be like normal children and run outside, holding aloft a TV antenna.

 

[Ziggurat]

There are a lot of sources that claim surge protectors can't protect from a lightning because there simply is too much current and the only way to effectively protect any device is to unplug it during storms. On the other hand, several manufacturers say that their protectors, when overloaded, will get damaged themselves but will cut the power to the devices and so it's effectively the same as unplugging them. And there is also the odd anecdotal report of people who say that after a lightning they lost many sensitive devices but those plugged in a surge protector survived. So what's the deal ? Is it possible to 100% protect from a lightning with a surge protector ?

My understanding is that surge protectors take a bit of time to respond. If the surge is fast enough, then it can fry the equipment even with a surge protector. So surge protectors are not 100% guaranteed.

But they work a lot of the time. If a lightning bolt hits your house directly, maybe it won't prevent damage, but most of the time, the bolt isn't going to hit your house directly. Most of the time, it's going to hit farther away, and the surge hitting your house will be a small fraction of the total lightning current, with the pulse broadened. In those case, which are much more common, a surge protector can protect your stuff.

 

[William Parcher]

...for the purpose of protecting against electrical surges and spikes, including those caused by lightning...

It discusses the speed at which they protect and that the surge is usually not suddenly devastating (it builds). The suppressor acts before damage is done to what you are protecting.

https://en.m.wikipedia.org/wiki/Surge_protector

 

[RussDill]

Yup, what ceptimus says. Surge protectors are rated for a certain level of protection. None of them will be rated for a direct lightning strike. The amount of surge that reaches your house in the event of a lightning strike (or other disturbances of the grid) will depend on how far away you are. With no surge protection, a lightning strike much further away can damage your equipment than with a surge protector.

I did computer tech work for some time and can confirm that nearby lightning strikes do in fact damage computer equipment. Anytime there was a big storm, it was almost certain I'd receive at least one call of "computer won't turn on". Each time the damage was limited to the power supply. I'm sorry, but I don't remember if any of the computers had a surge protector.

The other important thing about surge protectors is that the act of protecting against a surge actually wears the internal electronics. Good quality ones have a light that remains lit while there is sufficient protection left. Of course, some are just lights connected across the mains and mean nothing, and some don't have any protection at all. How often will depend on how many surges you get, but it's general a matter of years, not decades.

Here's a good 5 minute teardown and discussion: