Lightening strike neaby -- some damage

[Ed Pawlowski]

"John Grabowski" wrote

Good point John. There is a ground rod and I will check it.

[Ed Pawlowski]

"Tony Hwang" wrote

All overhead. Just down the street from me they do have underground wires and a different feed from the substation. We get a short power outage maybe once or twice a year, usually a few minutes to an hour. They fare only slightly better than us as the lines to that group of houses is all overhead anyway.

[westom]

Single point ground is only the start of protection. For example, telephone lines already have a 'whole house' protector installed for free. But that will only be as effective as the earth ground it connects to. You are responsible for that ground. IOW cable TV, telephone, satellite dish cable, and all three AC electric wires must make a short ('less than 10 foot') connection to that same earth ground.

Cable needs no protector. A short wire must connects the cable to that single point ground. No protector does protection. Protector only makes a connection from each wire to earth. Earth does the protection.

Only one AC electric wire is earthed. You must install a 'whole house' protector to earth the other two. If not, then you still have ineffective protection.

Nothing (ie a millimeter gap) will protect from destructive surges. Protection means energy is not inside the building. Either a direct lightning strike (ie to utility wires) is harmlessly earthed without entering the building. Or that surge will seek earth destructively via appliances. It is that simple. Nothing inside a house will stop or absorb a destructive surge. If permitted inside, that energy will find numerous paths destructively via appliances.

A direct lightning strike is typically 20,000 amps. So a minimally sized 'whole house' protector is 50,000 amps. More responsible companies such as Intermatic, Leviton, Keison, Square D, Siemens, and General Electric sell these. A Cutler-Hammer protector sells in Lowes and Home Depot for less than $50. Earthed protectors are installed so that direct lightning strikes cause no damage =96 even to a protector.

Page 42 Figure 8 shows what happens when a surge is permitted > A very important point to keep in mind is that your surge protector will =

work by diverting the

s if grounding is

Three AC wires enter the building. One (the neutral) should make a short (ie 'less than 10 foot') connection to that earthing electrode. Other two do not connect to earth IF a 'whole house' protector is missing. If any incoming wire does not connect to earth, then surge energy is inside the house - destructively. Your protection is always

- always - about where energy dissipates.

Same also applies to lightning rods. Also as effective as its earth ground. If no lightning rods, then that is an incoming path for that energy. Generally most destructive surges enter via incoming utilities wires (overhead or underground). But if more aggressive protection is required, then also consider lightning rods.

In every case, no magic box averts surge damage. Either a protector or lightning rod makes a short connection to earth. Or you have ineffective protection. The most critical component in lightning protection (from direct strikes) is the earth electrode - the only component always required in every protection system. So critical that many expand that earthing. Earthing that must both meet and exceed post 1990 National Electrical code.

Above was only the secondary protection system. Also inspect your primary protection system. What provides the protection? A picture of what to inspect:

[trader4]

Like the smaller point of use surge protectors can't also be overcome by a surge? I'd rather have the first line of defense be a 50K amp capable one than a much smaller rated strip type protector. They are good as a second line of defense and to keep all wires clamped to the same level, ie AC, cable TV, phone, etc. But they are no match for a big one at the panel.

The same thing still applies if you have a plug-in surge protector or APC. Almost all these companies are not very good at paying out claims.

[trader4]

I guess anyone that has a whole house surge protector installed at the panel in the basement or garage should go take it out. You know, those surge protectors made for exactly that type of installation by all those companies on your list of "responsible" manufacturers.

I'm still waiting for the link to that $50 50,000 amp rated surge protector at Lowes.

Yawn. It's widely known that MOVs degrade over time when subjected to surges. So, in fact, while they can protect equipment, they are in fact often damaged as a result.

l work by diverting the

e useless if grounding is

[bud--]

For phone, cable, satellite... the important point is connection with a

*short* wire to the ground/earthing at the power service. With a strong surge the building ground can lift thousands of volts above absolute" ground. Much of the protection is that power and cable and phone and satellite wires lift together.

Doesn?t need a protector? The IEEE guide says ?there is no requirement to limit the voltage developed between the core and the sheath. .... The only voltage limit is the breakdown of the F connectors, typically ~2?4 kV.? And "there is obviously the possibility of damage to TV tuners and cable modems from the very high voltages that can be developed, especially from nearby lightning." (A plug-in suppressor will limit the voltage from core to shield.)

(Links to the IEEE and NIST surge protection guides was in my first post.)

w has a religious belief (immune from challenge) that surge protection must directly use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. The IEEE guide explains plug-in suppressors work by CLAMPING (limiting) the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

If using plug-in suppressors note that all interconnected equipment needs to be connected to the same suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires.

Service panel suppressors are a good idea. But from the NIST guide: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

The NIST guide suggests the major cause of equipment damage is high voltage between power and phone/cable wires. Service panel suppressors do not prevent that high voltage. To limit the voltage you need a

*short* wire connecting the cable/phone entrance protectors to the ground at the power service.

As explained in my other post there is essentially zero probability of a surge on power wires higher than 10,000A. But a 50,000A rating means the suppressor will have a long life.

All these "responsible companies" except SquareD make plug-in suppressors. SquareD says for their "best" service panel suppressor "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use."

A protector must earth (and not absorb) that energy. If not located

If poor w could only read and think he could discover what the IEEE guide says in this example:

- A plug-in suppressor protects the TV connected to it.

- "To protect TV2, a second multiport protector located at TV2 is required."

- In the example a surge comes in on a cable service with the ground wire from cable entry ground block to the ground at the power service that is far too long. In that case the IEEE guide says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector."

- w_'s favored power service suppressor would provide absolutely NO protection.

The whole point of the example is that plug-in suppressors are effective.

Of course not.

I explained in my first post where the energy goes. If poor w could only read and think...

What does the NIST guide really say about plug-in suppressors? They are "the easiest solution". And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

Plug-in suppressors are "magic" to w because his religious blinders do not let him see how they work - clearly explained in the IEEE guide.

Flying planes are crashing every day because they are hit by lightning ad have no "earthing electrode".

Never seen - a link to a reputable source that agrees with w that plug-in suppressors are not effective.

Never seen - answers to simple questions:

- Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors?

- Why does the NIST guide says plug-in suppressors are "the easiest solution"?

- Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?

- How would a service panel suppressor provide any protection in the IEEE example, pdf page 42?

- Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"?

- Why do your "responsible manufacturers" make plug-in suppressors?

- Why does "responsible" manufacturer SquareD says "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"?

For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.

[bud--]

In a post to harry I commented on 2 papers from Francois Martzloff, who was the surge expert at the US-NIST. The "big one" is 10,000A coming in on service wires. There simply is no reasonable probability of a larger surge. It is based on a 100,000A strike to a utility pole behind a house.

With that 10,000A surge and no service panel suppressor Martzloff looked at the energy dissipation at a MOV on branch circuits of 30 ft and longer. The maximum was 35 Joules. In 13 of 15 cases it was 1 Joule or less. That is well within the ratings of plug-in suppressors I have seen.

As I wrote in the post to harry, the reason for the small energy is that at about 6kV there is arc-over from hot bus to enclosure. After the arc is established the voltage is in the hundreds of volts. That dumps most of the energy to earth. And the second reason is that surge currents are relatively high frequency and the impedance of the branch circuit greatly limits the current that can reach a plug-in suppressor.

Surprisingly, the largest energy dissipation at the MOV was not even from the "big one". It was for surge currents below 5,000A. That was because the MOV at the end of the branch circuit clamps the voltage at the source and prevented arc-over at the source. Higher surge currents drove the voltage at the source to arc-over, which resulted in very low energy dissipation at the MOV.

So plug-in suppressors take a much smaller hit that one would expect. With very short branch circuits the hit may be larger, but suppressors with very high ratings are readily available for not a lot of money. One of the plug-in suppressors I am using is a major brand and cost about $25. It has ratings of 590J and 30,000A per MOV, 1770J and 90,000A total. The rating of 30,000A is higher than the current that can occur at the service - there is no possibility of that much current at the suppressor. The rating just goes along with the high energy ratings. The suppressor has a connected equipment warranty - the manufacturer doesn't think there is much probability of failure.

I think plug-in suppressors are quite likely to survive the "big one". But I certainly agree that a service panel suppressor is a real good idea, particularly where there is significant risk.

Martzloff has also written "in fact, the major cause of [surge suppressor] failures is a temporary overvoltage, rather than an unusually large surge". TOV is, for instance, a distribution wire dropping onto the wires that go to your house. (Someone here (Nate?) had that happen to them.)

And in the NIST guide Martzloff suggests that most equipment damage is likely caused by high voltage between power and phone or cable wires, a problem not solved by a service panel suppressor.

[thirtyplusomething]

Agreed, and If this was my house, I'd pull out every outlet, switch and light fixture and check for burnt stuff. The ends of wirenuts will blow right off, wires are bends will literally burn away sections. I know this because a neighbor got hit, and it took out all of his barn wiring and a section of the house. In the house, there were several wires burned, one hot lead was shorted to the ground wire inside the box. That breaker was ruined. In the barn, there was a main feed wire that blew a hole thru the insulation right where the wires bent at the breaker, the hot lead was welded right to the metal box, and thus tripped the main breaker feeding that barn (located in another building). In that building, there was a section of wire in the main panel that was so burnt that it caused a sort of resistor (a charred section of molten copper and carbon). The lights in there flickered. All of this had to be fixed.

After the power was restored to the barn, which controls his well water pump, the water was turned on, and we found a water leak in the basement of the house. Right in the end of a copper elbow, there was a pinhole, with water shooting out. Looked like the lightning just exited out that elbow rather than making the turn to follow the pipe. The pinhole was a noticable burn, not just a hole caused by corrosion.

In another situation, where I lived about 28 years ago, a friend of mine had his telephone explode. One of the old wall phones. It took out a whole section of sheetrock and left nothing but chunks of plaster and phone pieces all over the floor. The phone company had to rewire everything from the phone, throughout the whole interior of the house, outside the entire underground wire to the box along the road (whatever they call those connection box things), and even some of the wire feeding that connection box. The telco guys told him that the wires were nothing but plastic with no copper left in them. I saw a section, just melted plastic insulation. He was lucky there was no fire caused by that.

Anyhow, once you're hit by lightning, you really need to take apart all wiring and check it. Look closely in your breaker panel for charred stuff, and definately check grounding wires, clamps, etc.

[RonB]

It is a good time to take a test inventory of everything in the house that is electrical or might have a processor. We experienced a strike near the house last September and knew we had damage immediately. Computer was dead. Garage door openers were dead, Older TV dead. Our insurance agent told us to take our time doing a damage assessment because there is likely to be more. She was right. Over a period of two weeks we found out all of the local wireless providers network (antenna, modem, etc) was damaged - just took a few days to die. We found 6 GFIs that were damaged, all surge protectors in the house were dead. In addition to garage door opener circuit boards, one of the light sensors croaked within a week, etc, etc, etc. What looked like a $1,200 claim a couple of days after the strike ended up being more than $2,000.

We were up at 2:00am when it hit. It struck somewhere just north of the house but I never found the attach point. All north windows went pure white, as did the interior of the house and the noise sounded like an M-80 in a trash can, inside of the house! Noise and flash exactly concurrent. Scary by itself but we saw sparks flying out of a kitchen GFI and that lasted 2-3 seconds.

RonB

[Tony]

I've probably repaired 50 or so pinball machines that the symptom is after the lightning, it blows the breaker. The MOV is melted together. Most of the machines had no further damage. I forget the joules but radio shack had little ones and big ones. The equipment usually had the smaller ones but I only carried the larger ones for replacement. Some of the newer machines have the main fuse before the MOV, where it should be! Then there were others that didn't realize the breaker was tripped and after resetting it, the machine came to life. Many times the MOV was blown in half, and still there was no more damage. I'm talking some pretty sensitive electronics too. Probably a lot more sophisticated than most people think.

[bud--]

Normal failure mode for a MOV is to start conducting at lower voltages until it conducts on normal voltage and goes into thermal runaway and essentially shorts.

I used to have a homemade plug-in surge suppressor made with MOVs. I retired it because it didn't have good protection from failing MOVs. Since 1998, UL has required thermal disconnects for failing MOVs in UL1449 listed surge suppressors.

For a pinball machine I would want a fuse upstream from the MOV and electronics (like you said). If the MOV fails the fuse blows (if properly designed), the machine is disconnected, and you can't just reset a breaker.

[Ed Pawlowski]

"westom" wrote

A protector must earth (and not absorb) that energy. If not located

Lots of good info. Thanks for posting it.