View Full Version : Surge suppression / lightning damage

Dan Friedrichs
10-04-2017, 10:45 PM
Was making dinner the other night - no rain or thunder - when a bolt of lightning struck the house. Appears to have hit a metal chimney. The list of casualties is large:

Natural gas fireplace insert (all the control electronics)
Garage door opener
Cable modem (and enough of the cable company's distribution equipment that internet is still out, 48 hours later...)
Laser printer
Half-dozen LED and CFL light bulbs

Made me realize I never really thought about surge protectors (other than casually noticing them being built into power strips). Anyone happen to be an expert on this topic? :)

Are breaker-box-mounted "whole house" surge protectors effective? How about the power-strip-included variety - would those help at all in this type of situation? Or are they a gimmick that's easy to sell because no one ever gets to do a side-by-side comparison (with/without protection installed)?

John K Jordan
10-04-2017, 11:24 PM
... Anyone happen to be an expert on this topic? :)

Are breaker-box-mounted "whole house" surge protectors effective? How about the power-strip-included variety - would those help at all in this type of situation? Or are they a gimmick that's easy to sell because no one ever gets to do a side-by-side comparison (with/without protection installed)?

I am certainly no expert. My electrical supplier (whom I trust) said the whole-house protectors really work for many surges - a nearby city is installing them on every house. They will protect from a voltage spike up to a certain energy level, typically from some lighting strike some distance from your house. The surge protectors built in to power strips are very weak - they are often just a varistor or two across the AC terminals. They will swallow a mild spike up to a certain level but not much. Note that surge protectors will usually burn out instantly with a strong spike and everything plugged in will still be at risk.

There is nothing that will stop a direct lighting hit other than maybe a Faraday cage. It can travel through all wires and jump gaps, fry everything connected, vaporize things, cause things to explode and catch on fire, and kill things alive. The energy in a lightning strike is unimaginable.

It used to be that almost every house had lightning rods on the roof connected to the ground with heavy conductors. I hardly ever see them today except on large buildings. (I did see lightning rods recently on a house built in the 1800s) They work better in some circumstances than others mostly depending on what type of ground you have (sandy, rock, swamp), so you might want to investigate. Maybe search Google or read this: http://today.tamu.edu/2012/02/29/lighting-rods-work-says-expert/

Farmers put special lighting arrestors on electric farm fencing since thousands of feet of wire makes a huge target for lightning.


Jim Becker
10-05-2017, 2:31 PM
I agree with John...surges and lightning strikes are different animals, despite the fact that electricity is involved with both. The former is generally an even "on the grid" and having either whole house or spot protection for sensitive devices is a good idea and worth the cost. For the latter...damage is going to happen...since lightning is generally a major event that will overwhelm and literally jump over any type of "surge" protection when it wants to.

Lee Schierer
10-05-2017, 6:25 PM
A few years ago, while we were away from home, Lightning hit our flag pole in the front yard. I burned off the pulley swivel at the top of the pole, followed the pole to the ground where it found the in ground dog fence wire about 4 feet from the flag pole. It vaporized the doge fence wire for about 100 feet each way from the place where the loop split off the twisted pair. It also followed the twisted pair into the house where the lightning protector for the fence put it into our electrical system. It blew up our septic high level alarm, took out our Directv receiver and one or two other small electrical items. A whole house surge protector would not have protected them because the surge came from the house side, not the electrical system side. The power strips with surge protectors protected other devices in the house. So I would recommend having both a whole house sure device and individual ones for electronics.

Ken Fitzgerald
10-05-2017, 6:44 PM
While working air traffic control maintenance at NAS Meridian, I had to deal with the results of a lightning strike that hit about 200 yards from the mobile precision approach radar and ran into the radar via the power lines buried below the ground in nitrogen charged metal conduit. I am a fairly large man. Where it entered the "power trailer" it welded the two halves of a cannon plug and jack (the diameter was as big as my fist) together when it melted the 4 pins, each of which were as big as my thumb. That welded plug/jack was just the beginning of our problems. Each phase of the incoming 3 phase power had it's own regulator. The regulators had to be replaced. Then we got to troubleshoot and repair the dozens of chassis within the radar itself. We were a couple weeks recovering and it wasn't even a direct strike. Men in a crash crew truck were parked about 10 yards away observed the strike and that's why we knew it wasn't a direct hit but ran the ground was struck some 200 yards from the radar.

I agree with Jim....and Lee. A surge protector will help with surges but won't have much affect for a lightning strike.

Wes Thom
10-06-2017, 10:02 AM
Was making dinner the other night - no rain or thunder - when a bolt of lightning struck the house. Appears to have hit a metal chimney. The list of casualties is large:

Appliance protection is confused with structure protection. Had a chimney been protected by a lightning rod or had been properly earthed, then no surge current was inside hunting for earth destructively via appliances. That is structure protection. Protection is always about the path that current takes to earth. If that current connects to earth on a path that is outside, then best protection already inside every appliance is not overwhelmed. A properly protected chimney means no current was in or inside that structure.

That is a human mistake that made damage possible. Meanwhile, more common are surges that strike AC electric wires or strike earth many yards from an electronics bay. All those are examples of direct lightning strikes. All are examples of why 'whole house' protectors are so effective and necessary.

Lightning rods never do protection. Protectors never do protection. Both are effective only if connected to what does the protection - earth ground. Effective (and least expensive) protection is always about where hundreds of thousands of joules harmlessly dissipate. That solution only exists with properly earthed lightning rods and 'whole house' protector.

How many joules does that plug-in protector claim to absorb? Hundreds? Thousand? Never ignore spec numbers. A surge that tiny is routinely converted by electronics into rock stable, low DC voltages to safely power semiconductors. Why would anyone spend so much money on near zero joule protectors. Magic box protectors only protect from surges that are really only noise. A surge, too tiny to damage appliances, may destroy that near zero joule protector.

Surge protection is always about lightning and other similar transients. Any protection that does not protect from all surges (including lightning) is bogus. A profit center. Near zero protection. Ineffective. Protection is always about where even hundreds of thousands of joules are harmlessly absorbed. A properly earthed 'whole house' solution does that for about $1 per protected appliance. It remains functional for decades after many direct lightning strikes.

Profit center protectors fail on a direct lightning strike or other lesser surges. Undersizing increases profits and gets the naive to recommend it.

He replaced what was damaged but failed to avert future damage. He did not learn a strike 200 yards distant was a direct lightning strike. An industry professional Tech Note demonstrates how a nearby lightning strikes is actually a direct strike to electronics:
Direct lightning strikes to any distant wire (overhead or underground) requires same properly earthed 'whole house' protection. It did not exist. So lightning found a best and destructive path through radar electronics. Nothing new. This type direct lightning strike and resulting damage is why, for example, telco COs suffer about 100 surges with each storm. Using over 100 years of knowledge, then direct strikes do not destroy a $multi-million switching computer. They install 'whole house' protection. And worry less about the protector; more about what actually does protection - single point earth ground.

An IEEE Standard puts numbers to it. If properly earthed, then 'whole house' protection will do 99.5% to 99.9% of protection. No, it is not perfect protection. IEEE puts more numbers to it.
Still, a 99.5% protection level will reduce the incidence of direct strokes from one stroke per 30 years ... to one stroke per 6000 years ... Protection at 99.5% is the practical choice.
If power strip protectors did protection, then listed is damaged dishwasher, furnace, every GFCI, all smoke detectors, central air, door bell, stove, dryer, and all clocks. What protected some or all of them? Invisible protectors? Of course not. That logic is called cherry picking - also called junk science. For that conclusion to be valid, then every appliance not on a protector must be destroyed. Now move on to how surges do damage.

A surge is incoming to everything. Why is everything not damaged? Because electricity also must have a simultaneous outgoing path. Surge was incoming to everything. It went hunting. It only found an outgoing path destructively via some applianes. No plug-in protector changes or averts that destructive hunt.

That properly earthed 'whole house' protector is only a 'secondary' protection layer. Symptoms in both house damage and radar electronics imply a 'primary' protection layer was also missing. That results in something with much higher energy - a follow-through current. Highest energy comes from the AC utility; not from lightning. A list of damaged appliances also implies the 'primary' protection layer was missing.

Pictures (definitely not text) about half way down and after the expression "more safety hazards" demonstrate missing 'primary' protection. Informed homeowners do not only properly earth a 'whole house' solution (and waste little money on plug-in protectors that have no earth ground). Informed homeowners also inspect their 'primary' protection layer. Otherwise a direct strike (to earth or to overhead wires) 400 yards away can be a direct strike incoming to all interior appliances.

Never spend tens or 100 times more money on that near zero joule plug-in box. Always earth a 'whole house' solution. Then best protection already at each appliance is not overwhelmed. Hundred or thousand joule surges are only noise - do no damage. Surges that exceed what a plug-in protector claims to protect from may be safely consumed by appliances. Or do damage because the homeowner failed to properly earth a 'whole house' solution. Even those plug-in protectors (near zero joules) must be protected by a 'whole house' solution.

Another indication of misinformation. Too much discussion about the protector. And virtually nothing about THE one item that must always exist in every protection layer - earth ground. A protector is only as effective as its earth ground.