I'm considering buying a lightning protection unit for my electronics at home and would love some assistance in understanding how it all works. I live in an area where lightning strikes are very common and would like to buy/install something specifically for lightning protection.

I was looking at surge protectors that claim a joule rating of 1800+ joules. Now, in my limited understanding, a lightning strike packs much more punch and I need something more capable.

So here's my question - would a device with a rating of say 1800 joules be able to protect my electronics and if not, what do I need to look for in a surge protector?

How about surge protectors that claim they can absorb "20 000 Amps" on live, neutral and earth?

  • 1
    \$\begingroup\$ You are correct that there is much more energy in a lightning strike, but only a tiny fraction of that energy is likely to be dissipated in your home electrical system. \$\endgroup\$ Commented Feb 16, 2016 at 17:11
  • \$\begingroup\$ Start by making sure that your electrical system ground is properly done, in good shape, and that all things that should be bonded to it ARE bonded to it. \$\endgroup\$
    – Ecnerwal
    Commented Feb 17, 2016 at 0:37

4 Answers 4

  1. Most surge protectors are made to handle 'transient events' caused by other devices in a power distribution system, such as an un-controlled voltage spike from an improperly switched inductive load (or a related switch failure).

  2. A 'direct hit' from a lightning strike cannot be directly 'stopped,' neither can any consumer-grade surge suppression device (at least none that I'm aware of) fully 'handle' the power of such a surge without catastrophic failure of the device, and likely damage to your electronics.

  3. The proverbial 'first defense' against lighting damage to your equipment should be the use of external lightning ground-path protection, such as installing 1/more lightning rod(s) which reach above the highest point of your incoming power line (providing a more likely 'target' for the lightning current to 'strike' in order to reach ground without going through your home wiring).

  4. After taking sufficient measures to avoid 'taking a direct hit,' you can use consumer-grade surge suppression devices (like the ones you're asking about) to provide an added degree of protection to your devices, to lrotect against capacitively, or inductively coupled surges joining your wiring system from wires that run near the path a lightning current took to reach ground.


The more Joules the better, if you want to protect your electronics, unplug them.

If you've ever ripped apart a surge protector there is not much to it. Most of them have just one or two MOV's in them, this will protect you from secondary effects by clamping any voltage significantly above the line voltage.

When lightning strikes it has a direct path, some indirect paths, and generates a large EMP. That means that any cables or metal for that matter, are going to turn into antennas and carry a large voltage on them in the 100's of volts.

Your surge protector will clamp these spikes and maybe an indirect spike from lightning hitting nearby.

A direct strike on your house or on a nearby line and it's game over, with 1000's or maybe even 10000's of volts coming down the line there is no way to stop it.

I had an uncle that had a line near his house get hit and it fried every other thing in their house. Some things were fine (dryer fine, washer died) and some things not. Their computer had a dead PSU but everything else in the computer worked.

They say a UPS won't help, but I can't help but think that it would take care of a lot of the indirect strikes because of this.


Surge protectors really need something between it and the high energy source to dissipate the energy. Some surge protectors tell you there needs to be 'N' length of wire to the panel to be effective.

Don't overlook stuff like phone lines and other devices that can bring a different ground potential into the overall system and fry stuff that way.


As it has already been said, the electricity of a lightning bolt is too great. A small surge protector doesn't work against lightning strikes. I find this explanation of lightning protection very interesting https://www.streamer-electric.com/products/lightning-protection, what would help you is a whole-house lightning mitigation system.


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