In keeping with what Brickeyee stated about lightning following the wire, about 10 years ago I was working for a company installing sheet metal HVAC duct on a hospital project in Pensacola, Fla. We were on the 5th floor of a 6 story section which had the structural steel, steel decking and the concrete floors poured but the exterior walls were all still open. About 25' from where we were working there was a man making a butt joint weld on an 8" iron pipe for the chill water distribution system. At noon we all broke for lunch and went to our gang box and sat down, but the welder kept on working. All of the sudden, KA-BOOOOOM, Lightning struck the end of that 8" pipe where it still extended slightly over the edge of the building. We literally watched as a blue-white haze ran the length of the pipe, then through the welders hand and followed his stinger lead across the floor and over the side of the building about 150' away. We were all froze motionless, knowing only too well that the poor welder must be dead, then just as casual as you please, the welder reached up and lifted his hood, got to his feet and hollered over to us, "Did you guys see that? The damn welding rod just exploded into nothing, I never saw anything like that before in my life! WE ran over to him, thinking he had to be in shock or something, but believe it or not, he was totally unscathed, not so much as a minor burn save for the black scorch marks on his heavy leather gloves. When we told him what happened he couldn't believe it, but then he just fitted another welding rod, dropped down on his knee and said, I got to finish this weld before i go to lunch. He then tried to strike and arc and nothing happened so he walked over to the side of the building and looked down at the huge trailer mounted Hobart welding rig, or at least what was left of it. All four tires were blown off the trailer and the entire rig was on fire. The superintendent had seen the original lightning strike and saw the generator catch on fire so he had called the fire dept and they were just arriving as we looked down. Later the welder told us that the lightning had totally fried the windings in the generator and blew a hole in the diesel engine fuel tank, so it was the fuel that we saw burning. When they rolled up the stinger leads it was also discovered that there was a 8" wide scorch mark on the concrete deck all the way from the welders position to the point where the stinger lead went over the side of the building. It is believed that it was the stinger lead that saved the welder by directing the lightning through the insulated handle of the welding stinger and on to ground.

It's an old thread, but the discussion made my blood boil. I'm also an engineer who designed and self-installed the pump filter for great hydraulic efficiency and very low power costs. It normally ran at 200 watts x 10 hrs/day versus the old setup (installed by a pool company) at 1500 watts x 14 hrs/day; run for 3.5 months/year. My Pentair INTELLIPRO XF VS PUMP drive burned out today. Had it for a little more than 3 years. I have a whole house surge protector. Pump is on a GFCI breaker. Traced correct power voltage all the way into the pump wiring terminals. The drive is non-servicable because some of the components are electrically potted into the housing to protect from moisture. Local Pentair dealer quoted me $1600 for a new drive (Pentair 356878Z) that is listed online for $680. He then quoted me $2100 for a whole new pump (Pentair 022055) that is listed online for $1300. I would pick up the part from the supplier's store and install it myself. Same part lead time as an online order. I don't mind paying an extra $150 to support the local guy, but an $800 markup is outrage! How can any of you say that customer service is worth $800? I troubleshooted it, I sought out the local supplier, I would install it myself. Pentair is not going to stand behind an out-of-warranty product. Is everyone saying that if I originally over paid my local Pentair dealer $800, he would remember me 3+ years later and replace the drive 'at no cost' to me. He'd still be making $120 profit on me for something that really should be covered by Pentair and should never fail - as discussed by others above.

brickeyee wrote: "Ufer grounds can easily be created during the construction of reenforced concrete buildings by ensuring bonding of the reinforcement bars electrically (often by welding them together). When they are buried in concrete you create a very effective earth ground." Under the US National Electrical Code a "concrete encased electrode" is usually required for new construction. The required minimum length is 20 ft and can be 1/2" rebar tie-wired together where necessary. I agree they are good. Ground rods are lousy. brickeyee wrote: "The 'surge suppressor' devices (MOVs being a very common type for this) allow for a connection between wiring and ground/neutral when the voltage exceeds their break-over rating. This has the effect of clamping the voltage on the line to approximately the break over voltage of the device. If the surge current is not very large or very brief the power dissipated in the device (current times break-over voltage times time conducting) will not cause destruction of the device" Maximum service surge current is 10,000A per service wire. Service panel protectors with much higher ratings are readily available. The author of the NIST surge guide looked at the amount of energy that might actually be absorbed in a plug-in protector. Branch circuits were 10m and longer. Power line surges were up to 10,000A (as above). The maximum was a surprisingly small 35 joules (based on US wiring). Plug-in protectors with far higher ratings are readily available. brickeyee wrote: "For MOVs it does cause some localized damage that decreases the ability of the device to carry current the next time it breaks over into conduction." As MOVs absorb surge energy they eventually start to conduct at lower voltages. Eventually they conduct at normal voltages, and go into thermal runaway. (Since 1998 UL has required listed protectors have thermal disconnects to disconnect overheating MOVs.) Far as I know MOVs continue to conduct surge currents up to failure. (Protection is not by absorbing the surge, but some energy is absorbed in the process of protection.) brickeyee wrote: "In the most common description the device is said to 'suppress' or 'shunt' the surge to ground. A poor connection to the source of the surge can result in limited effectiveness, and that includes the path back to earth ground for surges referenced to earth ground. The impedance of the ground path ads to the voltage the clamping device needs to turn on, decreasing its effectiveness at liming the voltage rise." For a power service protector the MOVs are connected line-to-line and line-to-neutral. In US services the neutral is bonded to ground and the earthing electrodes at the service. Unless the wires connecting the MOVs are too long they will function as intended, limiting the voltage between hots and neutral. If the earthing path is higher impedance it means that the power wiring will rise to a higher voltage above 'absolute' earth potential. With significant surge earth current it will rise in any case. Much of the protection is that all wires - power, phone, cable, ... - rise together as explained in another post. The same happens at plug-in protectors. All wires to a set of protected equipment has to go through the protector. The protector limits the voltage on all wires to the ground at the protector. As explained in the IEEE surge guide (starting page 30) the voltage at the protector may rise well above the ground at the service but the voltages between wires to the protected equipment is safe. brickeyee wrote: "Luckily the insulation on the phone lines usually fails around 4,000 to 6,000 volts (line to line of each pair) providing at least an upper limit on what is transmitted for many distances." Interesting - I never saw a breakdown number before. In US services, when service panel busbars reach about 6,000V there is arc-over to the enclosure. After the arc has stabilized the voltage is hundreds of volts. (Since the enclosure is connected to the earthing electrodes that dumps most of the surge energy to earth.) Similarly, 15 and 20A US receptacles will arc-over at about 6,000V. I generally agree with brickeyee. ========================== westom wrote "A 33kv wire fell on local distribution. Electric meters literally exploded up to 30 feet from their pans. My friend properly earthed one 'whole house' protector. Had no damage except to his electric meter." MOVs can conduct thousands of amps for the maybe 100 microseconds of a lightning surge. They will be rapidly destroyed by crossed power lines. No protector will say it can protect from crossed power lines. (UPSs and a few plug-in protectors disconnect on over-voltage and may provide protection.) westom wrote "Surges (ie lightning) may be 20,000 amps." The maximum surge current that has any reasonable probability of occurring is 10,000A per service wire - worst case. There is a reference to it in the IEEE surge guide. westom wrote "A protector is only as effective as its earth ground" Next worst surges to lightning are normal and abnormal utility operations including fault clearing and switching power factor correction capacitors. Many of them are line to neutral, not earth. I agree with brickeyee. Airplanes are regularly hit by lightning and have no earth connection. Understanding the protection is not that difficult.

Nicole wrote: "I agree with the idea the surge protected outlets should not be working, ... Out of 5 TV's, why did 1 make it...? We just keep shaking our heads." Everything observed is consistent with how and why surges do damage. Either a surge connects low impedance (ie less than 10 feet) to earth before entering. Or that surge is all but invited inside to hunt for earth destructively via appliances. Assume a surge was incoming on a typical path - AC electric. A surge is incoming to every household appliance. Are all damaged? Of course not. It is called electricity. That means a current is incoming on one port while that same current at a same time is outgoing on another to earth. If both paths do not exist, then no electricity and no damage. That explains why some are damaged; others are not. If plug-in protectors did as assumed, then everything without one was damaged - including a dishwasher, furnace, all clocks, any recharging electronics, door bell, smoke detectors, all GFCIs, central air, telephone appliances, etc. Knowledge means not ignoring exceptions. Best protection at each appliance was already inside each appliance. Plug-in protector did what its specification numbers said it would do for this type of surge - nothing. If one appliance makes a better and destructive connection to earth, then it is protecting robust protection inside other appliances. TV cable must already have best protection - as required by regulations, codes, industry standards, etc. So what is a best outgoing path to earth? Appliances connected to cable. Damage is often on the outgoing path (ie cable); not the incoming path (ie AC electric). Damage is a human failure. Effective protection has been well understood and installed over 100 years ago. Unfortunately, most consumers ignore spec numbers and science. Most consumers listen to naive friends, wild speculation, sales brochures, and advertising. Protection is always about where hundreds of thousands of joules harmlessly dissipate? How many joules does each protector claim to absorb? Hundreds? A thousand? Just enough above zero so that a consumer *knows* it is 100% protection. Cable company installs best protection for free - a hardwire connected low impedance (ie less than 10 feet) to single point earth ground. Earth ground does protection. No protector required. Other incoming utilities (ie telephone, AC electric) cannot connect directly to earth. So a 'whole house' protector does what that hardwire does better. Makes a low impedance (ie less than 10 foot) connection to earth. Telco installs this for free. It only exists on AC electric if a homeowner installs it. Then a surge dissipates harmlessly outside in earth. Then a surge is not inside hunting for earth destructively via appliances. More numbers. Lightning is typically 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. Any protector that fails is ineffective protection. This 'whole house' solution costs about $1 per protected appliance. How much was that plug-in protector that does not even claim to protect from destructive surges? $25? $85? Protection means one says where hundreds of thousands of joules are harmlessly absorbed. A protector is only as effective as THE most critical item in every protection system: single point earth ground. Then nobody knows a surge existed. Only that is effective protection - as found in every facility that cannot have damage. They also do not waste money on 'magic box' plug-in protectors. A protector is only as effective as its earth ground - that a plug-in protector does not have and will not discuss.