Fixing Static Electricity Issues: Tips from an Electrician

[dlgoff]

... if the past is any indicator of the future it will be until next August before I will know.

Dang. I hope I don't have to wait that long here in Kansas. We need the rain; let is storm.

 

[jim hardy]

"Got you on the bell wire. I was actually thinking of grounding the tracks to the Earth ground next to the barn. Any ideas there?"

i think that'd be fine.

 

[westom]

Got you on the bell wire. I was actually thinking of grounding the tracks to the Earth ground next to the barn.

Will only make damage easier as explained in previous posts that also said why.

Stop wasting time with myths about damage due to E-M fields. That was also explained with an example of how trivial that surge is. E-M fields even from lightning only feet away do not harm anything. Are made completely irrelevant by an NE-2 neon glow lamp. Please read that post multiple times to appreciate how silly that E-M field myth is.

Another example. Lightning struck the building lighting rod. Maybe 20,000 amps connected harmlessly to earth. Only four feet from that earthing wire was an IBM PC. All 20,000 amps from a direct lightning strike only four feet away is a 'largest' E-M field. That computer did not even blink. No hardware damage. No program crash. Damage due to nearby strikes is mythical due to superior protection already inside all appliances.

Now, listed are four wires from house to barn. All four have no earthing - two hot wires, safety ground, and neutral wire. A direct lightning strike to AC wires far down the street enters that barn via the house. What does a surge seek? Earth ground. Incoming on those two 'hot' wires. Through the opener. Out via the sensor. To Earth via the already grounded metal door tracks.

Your damage (in this example) is directly traceable to wires entering the building without first connecting to earth. Again, if any wire enters that barn without first being earthed, then nothing inside that barn can do any protection.

Not yet described is what can avert this. In part, because that is futile until you understand why damage is happening. What is lightning? An electrical connection from cloud to earth. A cloud is connecting to Earth via that Sears closer. If anyone wire enters the barn without first being earthed, then only protection is already inside the closer. In this example, a surge, so massive as to overwhelm that superior protection, is using a sensor wire to connect to Earth via the door tracks.

 

[jim hardy]

"""Now, listed are four wires from house to barn. All four have no earthing - two hot wires, safety ground, and neutral wire. ""

Safety ground and neutral are tied together (bonded) in the breaker panel and both are solidly earthed near the meter and again at the transformer, and i think he said at the barn too.

the em pulse from a nearby lightning strike is not trivial.

it can get into house wiring by two mechanisms -

direct connection : If lightning strikes top of a power pole, it gets into the bare copper earthing wire, and that's connected to the transformer center-tap and neutral, so your house safety ground and neutral wires are all connected directly by wire to the bottom of a lightning bolt.
That makes the whole system inside your house elevate well above "earth" potential for the duration of the lightning stroke. It doesn't hurt anything because all the wires "float" together like surfers riding a wave.
I know this first-hand because i was once using a properly grounded Sears metal electric drill when lightning hit my power pole outside. Earth i was standing on was at lower potential than Earth over at my power pole, to which i was connected by my safety ground wire. Quite a shock! A lightning bolt lasts long enopugh for you to say "GAAAHHHH" and throw the drill.
that's why your PC survived - it's a closed box so its internals saw no potential difference.
My drill was fine, it was i who saw the potential difference.

Note that a surge suppressor will see no potential difference either in that scenario.
Fortunately he has underground feed to his transformer, no house-side connection to pole. Unless there's an Earth ground on primary side of his transformer.

it can also get in via induction and there's two flavors of that:
1. if lightning throws a pulse across the electric company's mains it can come through your transformer, inductively coupled, as a stepped down but still high voltage pulse and blow stuff up from simple overvoltage. Surge suppressors are good at arresting those.
2. Old fashioned induction - this is the sneaky one ..
a loop is as i described, an antenna. Being a loop it has inductance. A lightning stroke has fast current rise times hence its magnetic field does too. Any sizeable loop nearby will have voltage induced in by the flux from the lighniing bolt it according to Biot-Savart. This effect tripped my power plant one day. But it requires a close hit. So something at the end of a long safety ground wire can get shaken by induction in that length of safety ground wire between the device and the system earth.. fix is to Earth both exremities, hence the door frames.


that's why i asked about layout, trying to get a feel for size of area enclosed by his ground loops. He has thirty feet of loop completed by Earth between his barn groundrod and his power transformer ground rod.

I wonder how close the barn feed runs to the house feed? That defines area of that loop.

Probably his problem is much simpler and the suppressor will fix it.

old jim

 

[WHS SHOCKED]

"I wonder how close the barn feed runs to the house feed? That defines area of that loop."

Not sure what you are asking here. Can you explain further?

 

[jim hardy]

""Not sure what you are asking here. Can you explain further?""

Well if you took a surveyor's sketch of your lot showing house, barn, power transformer etc

and drew in where the power lines are

starting at the power transformer, the line going to house, then the line back out to the barn, then closing that polygon back to transformer by a straight line from barn's ground rod to transformer's ground rod (30 feet you said?)

you should drawn have a closed loop.
is it a long skinny one ( small area)
or a big fat one ( lots of area)
?
Any nearby trees show lightning damage?
Amount of inductive coupling into that loop is in proportion to its area.

Really it's pretty much just an academic question, for were anything significantly out of ordinary i think you'd have noticed other strange electrical happenings by now.

but it's good to be aware of what sort of electrical "antenna" we have constructed with our house wiring.

old jim

 

[WHS SHOCKED]

The line from the transformer passes about 10' in front of the barn and into the back of the house. That run is about 75'. Then it comes out of the house about the same place and runs back to the barn crossing over the original line about midway to the barn which is about 50' from the house. There wouldn't be much of a looped area. No trees in the area. There is a well fairly close to both runs. And no, there hasn't been any other problems in the barn or house. Knock on wood!

Thanks for the reply.

 

[gtacs]

""" Unless there's an Earth ground on primary side of his transformer.

Isnt the return on the primary side hard wired to the neutral of the secondary, and then directly to ground at the pole? (At a typical house transformer)

 

[westom]

Isnt the return on the primary side hard wired to the neutral of the secondary, and then directly to ground at the pole? (At a typical house transformer)

Yes. His claims may apply to certin unique situations not found here. Those grounds must exist as you describe for many reasons - including surge protection.

Meanwhile. the OP describes damage because Earth ground does not exist for that barn. (A wire grounded in the house is not earthing for the barn.) A surge is destructively using the garage door opener to connect to earth. He should be asking how to eliminate that earthing problem. His earthing is sufficient to meet code - for human safety. But insufficient for electronics safety. The OP has an electronics safety problem.

 

[gtacs]

We did add a ground for the pole barn where before it was grounded through the house where the power originates. Bill

In the OP he said they added a ground (im assuming and Earth connection). On a typical, professional, installation the barn would be fed from the main DP to a sub-DP via a 100A (mine) breaker. The sub-DP would then be earthed.

Something I am interested in exploring is, you said the "earthing at the house would not suffice for earthing at the barn" do you think the path of least resistance to the Earth would not be via the return on the receptacle it is plugged into? I had never considered this. I believe the OP'er said he had a 50' run to the house panel. I am interested in your thoughts on this.

 

[westom]

The sub-DP would then be earthed.

Something I am interested in exploring is, you said the "earthing at the house would not suffice for earthing at the barn" do you think the path of least resistance to the Earth would not be via the return on the receptacle it is plugged into?

As I kept saying in most every post. That barn is not earthed. It is earthed to meet code. Code only cares about human safety. It is not earthed for transistor safety.

The expression was posted repeatedly. "low impedance (ie 'less than 10 foot')" . Or "short (ie 'less than 10 feet')". That is why the barn has no earthing. Impedance - not resistance - is important. A low resistance wire can have high impedance.

A similar example. A 200 watt transmitter is broadcasting on a long wire antenna. Touch one part of that antenna to receive a well over 100 volt shock. Touch another part of that wire to feel zero volts. Why two different voltages on the same wire? Electrical concepts that an electrician would not and need not understand. Code is why he is not trained in these other relevant concepts.

That barn must have its own single point Earth ground. Every incoming wire - no exceptions - must connect low impedance (ie 'less than 10 feet') to those earthing electrodes. Four AC wires enter. All four must connect short to earth. One might connect directly (but that is not described). Others must be connected via a 'whole house' protector. Since WHS SHOCKED does not have this, then surges are inside the barn finding Earth destructively via the door closer.

Earthing must both meet **and exceed** code. That Earth ground 30 feet away at the house means the barn is sufficient to meet code - but not provide surge protection. Impedance is only one reason. If the necessary concepts are understood, then zero volts and 100+ volts on two different antenna wire locations also is obvious.

 

[jim hardy]

his wire lengths are insignificant compared to wavelength of 60 hz, so i see no standing wave issue.

Electricity wants to get back to where it came from. (KCL)
Lightning wants to get back into earth.
Power surges want to get back to the transformer winding (which has been checked by power company to be well earthed) .
If that ground rod at barn goes deep enough it should do a pretty decent job for both.

i would think.

That garage door opener has a design flaw and that's why there is a "protector" made specifically for it.

old jim

 

[westom]

his wire lengths are insignificant compared to wavelength of 60 hz, so i see no standing wave issue.

You are assuming a surge from the wrong source. Destructive surges are microsecond events. Protection installers are gnarly even about sharp wire bends, ground wires not inside metallic conduit, no splices, separation from other wires, etc. Low impedance is not about a thicker wire. Lower impedance is about shorter wire - ie 'less than 10 feet'.

Safety ground in receptacles can not perform effective earthing due to those and other requirements. For example, a 50 foot wire from a receptacle to breaker box might be well less than 0.2 ohms resistance. That same wire may be 120 ohms impedance to a surge. Code worries about resistance for human safety. Impedance and equipotential are critical factors in protecting that door closer.

One of many reasons why a house Earth ground does not Earth all wires entering the barn. Yes it does Earth for 60 Hz power. But a surge current typically is not 60 Hz power.

If 60 Hz power was on that antenna, then same voltage would be everywhere. Electric concepts to understand surge protection involve factors well beyond what a typical electrician learns. I was not talking about standing waves. I was discussing why a good electrician would not understand nor solve the OP's problem. And why others must appreciate the significance of low impedance (ie 'less than 10 feet').

 

[gtacs]

A similar example. A 200 watt transmitter is broadcasting on a long wire antenna. Touch one part of that antenna to receive a well over 100 volt shock. Touch another part of that wire to feel zero volts. Why two different voltages on the same wire? Electrical concepts that an electrician would not and need not understand. Code is why he is not trained in these other relevant concepts.

Westom, could you expound on this please, I like, Jim, thought you were referring to standing waves on the wire, and could not relate that to the problem. I looked for info. on long-wire antennas and could not find anything of value.

As far as the whole house protectors you mentioned, I did read a fair amount on those. It seems to me to be a good idea; apparently you can have your electric company install one for a nominal monthly fee. However, you still to use point of use protection as the whole house protectors handle higher spikes but react slower than the point of use

 

[jim hardy]

""I was not talking about standing waves. I was discussing why a good electrician would not understand nor solve the OP's problem. And why others must appreciate the significance of low impedance (ie 'less than 10 feet').""


You seem to feel OP's problem is a simple common mode pulse
and i feel it's a simple normal mode overvoltage

his surge protector sounds like it attacks both problems

so we'll probably never know

but i respect your opinion.

 

[westom]

As far as the whole house protectors you mentioned, I did read a fair amount on those.

Your telco's switching computer is typically exposed to 100 surges with each storm. How often is your town without phone service for four days while they replace their $multi-million computer? 'Whole house' protector was how protection was done even 100 years ago when operators had headsets attached to their ears during every thunderstorm. Technology is that well proven. And that little known when so many only know what advertising promotes.

Critical to protection is hundreds of thousands of joules absorbed harmlessly outside the building. Any homeowner can upgrade his earthing to both meet and exceed post 1990 code requirements. Increased earthing at massive cost makes minor improvements. Since earthing - not a protector - does protection, then high reliability facilities spend $thousands more on earthing to have that little better improvement. The point – a protector is only as effective as its Earth ground.

That antenna example demonstrated so many electrical concepts unknown even to electricians. That are critical to surge protection. Repeatedly posted was a one example: low impedance (ie 'less than 10 feet'). Even sharp wire bends increase impedance; subvert protection. Sharp bends are not a problem for 60 Hz electricity. But are a major problem for effective protection.

A ground wire inside metallic conduit is also not sufficiently conductive for surge protection.

More responsible companies provide these well proven solutions. Including ABB, Siemens, Leviton, Intermatic, General Electric, Polyphaser, and Square D. One 'whole house' protector for the entire house sells in Lowes and Home Depot for less than $50. Superior protection typically costs tens or 100 times less money. Effective protection is found in a profit center.

Lightning is typically 20,000 amps. So a minimal 'whole house' protector is rated at about 50,000 amps. Effective protection means direct lightning strikes are connected harmlessly to Earth outside the building. Even a protector is not damaged.

Effective protection means nobody even knows a surge existed. Even the protector does not fail.

All appliances contain superior protection. Your concern is a rare transient (typically once every seven years) that might overwhelm existing protection. Informed homeowners do what is done in every telco switching center, broadcasting station and even in munitions dumps.

Upgrade earthing. Connect every single wire in every incoming cable short (ie 'less than 10 feet') to single point Earth ground. That means protection from all types of surges (inclduing normal mode). Connection made either by a wire or by one 'whole house' protector. Then hundreds of thousands of joules dissipate harmlessly outside the building. Then nobody even knows a surge existed.

 

[jim hardy]

Thanks westom for that expound... now it's clear what you meant by

"" Connect every single wire in every incoming cable short (ie 'less than 10 feet') to single point Earth ground. "

not literally of course
but through an overvoltage(surge) protector.
I assume you are suggesting such a protector at entrance to barn?

Now it makes sense.

Are gas discharge tubes still the fastest ? I haven't messed with them in twenty years.
Perhaps you'd post links to spec sheets for a couple of your favorite protectors.



old jim

 

[westom]

Thanks westom for that expound... now it's clear what you meant by
"" Connect every single wire in every incoming cable short (ie 'less than 10 feet') to single point Earth ground. "

not literally of course but ...

Some wires have better protection when no protector exists. When the wire literally connects to Earth (ie satellite dish, cable TV, AC neutral wire). Other wires only have a protector (ie telephone) because, if earthed by wire, then service would not be possible. The NIST (US government research agency that studies this stuff) says same:
> What these protective devices do is neither suppress nor arrest a surge,
> but simply divert it to ground, where it can do no harm.

Divert as in bond, shunt, connect, conduct, or switch. Dr Kenneth Schneider writes:
>Conceptually, lightning protection devices are switches to ground. Once a
> threatening surge is detected, a lightning protection device grounds the
> incoming signal connection point of the equipment being protected. Thus,
> redirecting the threatening surge on a path-of-least resistance (impedance)
> to ground where it is absorbed.

All protector devices are more than fast enough. For example, an MOV must also state how many inches down its lead that speed test is conducted. Because even 2 inch leads will change the response time. Gas Discharge Tubes (GDTs) do not have life expectancy that other newer solutions (MOV, semiconductor) provide. GDTs are used when capacitance is important. For example, telcos replaced GDTs with other MOV like devices sometimes called 'the carbons'. And then obsoleted those with semiconductors.

Favorite protector depends on what is to be protected. For AC mains (the OP's problem), a best solutions come from more responsible companies including General Electric, Square D, Siemens, ABB, Intermatic, Leviton, and Polyphaser. All use MOVs - the best protector per dollar for that application. Are rated at about 50,000 amps. A Cutler-Hammer version sells in Lowes and Home Depot for less than $50.

 

[bud--]

Critical to protection is hundreds of thousands of joules absorbed harmlessly outside the building. Any homeowner can upgrade his earthing to both meet and exceed post 1990 code requirements. Increased earthing at massive cost makes minor improvements. Since earthing - not a protector - does protection, then high reliability facilities spend $thousands more on earthing to have that little better improvement. The point – a protector is only as effective as its Earth ground.

Point of use protectors do not work primarily by earthing a surge.

Excellent information on surges and surge protection is available from the IEEE:
<http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf>
A simpler guide aimed at the unwashed masses is from the US-NIST:
<http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf>

Lightning is typically 20,000 amps. So a minimal 'whole house' protector is rated at about 50,000 amps. Effective protection means direct lightning strikes are connected harmlessly to Earth outside the building. Even a protector is not damaged.

An investigation done by the author of the NIST surge guide found that the maximum current that has any reasonable probability of occurring on each hot service wire is 10,000A. (There is a reference to that in the IEEE surge guide.) That current is based on a 100,000A lightning hit to a utility pole adjacent to a house in typical urban distribution. It is very unlikely there will be a worse event.

The IEEE surge guide suggests a 20,000 - 70,000A per wire rating for houses for a service panel protector, or 40,000 - 120,000A in high lightning areas. Ratings far above the likely event current give a long life for the protector.

Service panel protectors are a good idea.
But from the NIST surge 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."

That is because the NIST surge guide suggests that most equipment damage is from high voltage between power and phone/cable/.. wires. Service panel protectors are likely to protect anything connected only to power wiring.

The NIST surge guide says:
"Intruder alarm systems using wires between sensors and their central control unit can be disturbed - and damaged in severe cases - by lightning striking close to the house. The wires necessary for this type of installation extend to all points of the house and act as an antenna system that collects energy from the field generated by the lightning strike, and protection should be included in the design of the system, rather than added later by the owner."

Damage with wiring acting as an antenna would require a nearby strike.

I expect the surge protector from Sears will eliminate the damage. Point of use protectors work by limiting the voltage on all wires to the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment. They do not work primarily by earthing a surge. For protection, all wires to a set of equipment must go through the protector. In this case, it sounds like the manufacturer did not provide internal protection for control wiring. (There is an example of how point of use protectors work in the IEEE surge guide starting page 30.)

All appliances contain superior protection.

Some equipment contains no surge protection. Little, if any, is "superior".

-------------------------------
Ground rods are not particularly good earthing electrodes. A very good resistance to Earth might be 10 ohms. If you have a 1,000A surge current earthed through a rod the system ground potential would rise 10,000V above 'absolute' Earth potential. About of 70% of the voltage drop through the Earth away from the rod is in the first 3 feet. The voltage to system ground a little way from the rod would be 7,000V or higher. Jim had a nice example of that. The potential of the Earth at the pole, house, garage and pole barn may be very different during a surge.

With the pole barn connected including a supply ground, pole barn system ground and earthing electrode and supply ground connect together. The neutral is not connected and neutral (and hots) can have a far different potential than the pole barn system ground during an 'event'.

Another way remote buildings could be connected in the past is no source ground wire and the building is connected like a service with system ground and earthing electrode connected to the neutral. I prefer this for surge protection. If you use a entrance panel protector, this uses a 3 wire protector, like at the service. For the connection above, a 4 wire protector is required, with separate ground and neutral wires. I would prefer to have my own entrance protector, not one supplied by the utility.

According to the IEEE surge guide, over 90% of protectors (service entrance and point of use) use MOVs for the voltage limiting element for power wiring. MOVs are plenty fast enough for surges. Gas discharge tubes take a short time to establish an arc and may not catch the start of the surge.

 

[bud--]

Some wires have better protection when no protector exists. When the wire literally connects to Earth (ie satellite dish, cable TV, AC neutral wire).

The building entrance protection required for coax (cable, dish) is a ground block that ties the coax shield to the building system ground. That does not limit the voltage on the center conductor, and the IEEE surge guide says that the center conductor to shield voltage is limited only by breakdown voltage of F connectors, typically 2000-4000V. 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."

The NIST (US government research agency that studies this stuff) says same:
> What these protective devices do is neither suppress nor arrest a surge,
> but simply divert it to ground, where it can do no harm.

Point of use protectors don't primarily protect by earthing a surge. The NIST (and IEEE) surge guides clearly say they are effective.

For example, an MOV must also state how many inches down its lead that speed test is conducted. Because even 2 inch leads will change the response time.

The response time is not affected. The clamp voltage is raised as the lead length gets longer. (This is covered in the IEEE surge guide.)

 

[jim hardy]

Those are two great links, Bud.

From IEEE: ""In general, there is little understanding of
how the different parts of the protection system need to work together."
Isn't that the truth! They tied up some loose ends for me..

Thanks!

As an IEEE guy you might enjoy "Modern Jupiter", a biography of Charles Steinmetz.

Steinmetz was GE's counterpart to Westinghouse's Tesla.
He built a lab to study lightning that was right out of a Mad Scientist movie.

An avowed socialist, he was written out of the textbooks in cold war years.
I only heard of him from an old-timer educated before WW2 , so i read that book.
https://www.amazon.com/dp/B0029Z1F2Q/?tag=pfamazon01-20
He is mentioned frequently (in present tense) in my 1901 electric motors book .
Maybe he's back in the textbooks by now - i don't know.
He sure deserves to be - he was as much a pioneer as Tesla, even if less colorful.



old jim

 

[gtacs]

Very informative links Bud, and thanks for the rewrite westom.

I am curious, what happens to the surge once it enters an AC to DC powersupply? Is the powersupply normally the failed component?

 

[westom]

From IEEE: ""In general, there is little understanding of
how the different parts of the protection system need to work together."
Isn't that the truth! They tied up some loose ends for me..

Those links provide important facts that Bud routinely forgets to mention. For example, the NIST says quite bluntly what a protector does when not properly earthed:
> A very important point to keep in mind is that your surge protector will work by
> diverting the surges to ground. The best surge protection in the world can be
> useless if grounding is not done properly.

That point was made repeatedly. Either a protector connects energy harmlessly to earth. Or it does ineffective protection.

That IEEE citation shows what happens when a protector is too close to electronics and too far from Earth ground. Page 42 Figure 8 shows the power strip protector earthing a surge 8000 volts destructively through TV2. Where is protection? Once energy is inside, then nothing stops a destructive hunt for earth. It will Earth via the connected TV or any other nearby appliances. A surge simply selects a best appliance to damage. In figure 8, TV2 was damaged when the protector earthed a surge 8000 volts destructively.

Bud said, "Point of use protectors do not work primarily by earthing a surge." So what do they do? If it does not Earth energy, then it must either stop, block or absorb that energy. How do 2 centimeter parts in a protector stop what three miles of sky could not? It doesn't. How does a protector (rated for hundreds of joules) absorb hundreds of thousands of joules? It doesn't. As long as claims are made subjectively, then a plug-in protector can do miracles. Once we add facts and numbers from the NIST, IEEE, and a long list of professionals, then a power strip is near zero protection.

Effective protection always means energy diverted (shunted, bonded, connected) harmlessly outside to earth. Otherwise a protector must somehow block or absorb that energy. No protector does that even though professional sales promoters routinely make that claim.

NIST said, "The best surge protection in the world can be useless if grounding is not done properly." Therefore protectors that will somehow block that current or somehow absorb that energy do not even claim to do protection. A professional sales promoter for power strip protectors claims plug-in protectors will magically stop or absorb surges. How? His NIST citation says otherwise. His IEEE citation shows how a protector, too close to appliances and too far from earth, grounded an 8000 volt surge destructively through a nearby appliance.

The NIST did not just called a plug-in protector ineffective. NIST called it 'useless'. Protection is always about where energy dissipates. Protection always means discussing where energy dissipates. Always.

Lightning surge is typically 20,000 amps. An IEEE paper from 1979 entitled "Coordination of Surge Protectors in Low-Voltage AC Power Circuits" shows a 100,000 amps surge to AC mains down the street. Figure 8 in that paper shows 30 kA going in other directions. 40 kA is earthed via a utility transformer ground. And 30 kA into the nearby house. In each case, surge current will find Earth ground. So that 30 kA remains that low, the utility's Earth ground must be intact. An informed homeowner inspects his primary surge protection system. A picture demonstrates what to inspect so that up to 40,000 amps obtains Earth out at the street. Does not seek Earth destructively via appliances and other homes. All homeowners (including the OP) are encouraged to inspect what is shown in this picture:
http://www.tvtower.com/fpl.html

Most will never see a 100,000 amp surge. Most lightning strikes are closer to 20,000 amps. So that all surges do not even damage a protector, a minimal 'whole house' protector starts at 50,000 amps. These are provided by more responsible companies.

Most of what his post is irrelevant to the OP's problem and a solution. But a coax protector claim demonstrates why cable TV does not need any protector. Richard Harrison, a broadcasting engineer who made lightning irrelevant all his professional life, said in "Lightning Arrester" in the newsgroup rec.radio.amateur.antenna:
> Coax, inside, rejects common-mode propagation of lightning energy.

That would only be understood by few who actually learn these engineering concepts. But more important is a fact relevant to the OP's problem. Common-mode explains damage to the OP's door closer. Common-mode is also why cable TV must always have its shield connected to single point Earth ground. And rarely needs a coax cable protector. What must always exist to have protection? Single point Earth ground. If selling protectors without earthing, then that engineering reality must be denied. If trying to avert more garage door failures, then AC wires entering that garage without earthing must be corrected.

IEEE even gives numbers in a Standard called The Green Book entitled 'Static and Lightning Protection Grounding':
> Lightning cannot be prevented; it can only be intercepted or diverted to a
> path which will, if well designed and constructed, not result in damage.
> Even this means is not positive, providing only 99.5-99.9% protection.

"Well designed and constructed" were defined previously. Short (ie 'less than 10 feet'), no sharp wire bends, ground wire separated from other non-grounding wires, no metallic conduit, etc. Missing earthing explains the OP's garage door damage.

Yes, the IEEE says plug-in protectors can add protection. But only if a 'whole house' solution is implemented. IEEE then says how much protection. A properly earthed protector does 99+% of the protection. That leaves a power strip to add maybe add another 0.2%. Yes, he is correct that a plug-in protector costing $40 or $100 might increase protection ... by another 0.2%. He also forgets to mention the power strip is "useless" without a properly earthed 'whole house' protector.

IEEE citation also says what only one properly earthed 'whole house' protector will do:
> 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 ...

The OP has garage door damage because 1) a surge entered due to no earthing, and 2) the surge found Earth destructively through that garage door. Protection is always about where energy dissipates. Any protector that will somehow magically make energy disappear is best called a profit center.

 

[westom]

I am curious, what happens to the surge once it enters an AC to DC powersupply? Is the powersupply normally the failed component?

The power supply is why electronics have protection superior to anything connected to its power cord.

Appreciate how power supplies worked even before the IBM PC existed. That 120 VAC is filtered. Then converted to high voltage (well over 300 volts) DC. Then filtered again. Then converted to high voltage radio waves. All part of making electronics immune from most anomalies on AC mains. And why transients also do not get through a supply.

Design standards in 1970 required 120 volt supplies to withstand 600 volts without damage. Today, standards require more like 1000 volt transients without damage.

A protector too close to a computer may sometimes bypass that supply protection. I just fixed a multifunction printer damaged just for that reason. It was on a power strip protector. Building owner is now installing 'whole house' protectors in all buildings to avert what has been repeat damage to electronics connected to power strip protectors.

 

[bud--]

As an IEEE guy you might enjoy "Modern Jupiter", a biography of Charles Steinmetz.

Steinmetz was GE's counterpart to Westinghouse's Tesla.
He built a lab to study lightning that was right out of a Mad Scientist movie.

An avowed socialist, he was written out of the textbooks in cold war years.
I only heard of him from an old-timer educated before WW2 , so i read that book.
https://www.amazon.com/dp/B0029Z1F2Q/?tag=pfamazon01-20
He is mentioned frequently (in present tense) in my 1901 electric motors book .
Maybe he's back in the textbooks by now - i don't know.
He sure deserves to be - he was as much a pioneer as Tesla, even if less colorful.



old jim

It is hard to be as "colorful" as Tesla (though it sounds like Steinmetz 'stood out'). I'll try to find a copy of the book.

Going through the 'U' in ee (not IEEE) I don't remember Tesla even being mentioned. One explanation I have read is that Tesla's patents (sold to Westinghouse) completely covered induction motors. Other companies regularly infringed on his patents, and it was not in the interest of other companies to recognize Tesla's contributions. One of the early standard texts was written by Steinmetz (GE) and minimized Tesla's contributions. Perhaps turnabout was 'fair play'?

 

[bud--]

Those links provide important facts that Bud routinely forgets to mention. For example, the NIST says quite bluntly what a protector does when not properly earthed:

Westom "routinely forgets to mention" what the NIST guide really say about plug-in protectors:
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in protector.

That point was made repeatedly. Either a protector connects energy harmlessly to earth. Or it does ineffective protection.

Nonsense.

Plug-in protectors do not work primarily by earthing a surge. Read the IEEE surge guide starting page 30.

Both the IEEE and NIST surge guides say plug-in protectors are effective. The IEEE surge guide has 2 examples of protection - both use plug-in protectors.

Westom seems to have a religious belief (immune from challenge) that surge protection must directly use earthing. Thus plug-in protectors, which are not well earthed, can not possibly work. He just ignores anything that contradicts his belief (like the IEEE surge guide).

Being evangelical, westom googles for "surge" to find places to spread his beliefs. Some of what he says is very good. Some not-so-good. About everything he writes about plug-in protectors is nonsense.

That IEEE citation shows what happens when a protector is too close to electronics and too far from Earth ground. Page 42 Figure 8 shows the power strip protector earthing a surge 8000 volts destructively through TV2. Where is protection? Once energy is inside, then nothing stops a destructive hunt for earth. It will Earth via the connected TV or any other nearby appliances. A surge simply selects a best appliance to damage. In figure 8, TV2 was damaged when the protector earthed a surge 8000 volts destructively.

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

- A plug-in protector 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."
- westom's favored power service protector would provide absolutely NO protection.

It is simply a lie that the plug-in protector in the IEEE example damages the second TV.

Westom tries to turn an example of how plug-in protectors work on its head.

Bud said, "Point of use protectors do not work primarily by earthing a surge." So what do they do? If it does not Earth energy, then it must either stop, block or absorb that energy. How do 2 centimeter parts in a protector stop what three miles of sky could not? It doesn't.

Of course it doesn't. Protectors don't stop or block. And neither service panel or plug-in protectors protect by absorbing. (Both absorb some energy in the process of protecting.)

I don't say point of use protectors do not work primarily by earthing a surge - the IEEE surge guide does. Just like the IEEE surge guide explains they work by limiting the voltage on each wire (power and signal) to the ground at the protector. And the guide says earthing happens elsewhere ( starting page 30).

How does a protector (rated for hundreds of joules) absorb hundreds of thousands of joules? It doesn't.

Of course it doesn't.

François Martzloff was the surge guru at the NIST and wrote the NIST guide plus many technical papers. One of them looked at the energy absorbed at a plug-in protector with no service panel protection. The branch circuits were 10m and longer, and the power service wire surge was up to 10,000A, which I said in another post is the accepted maximum probable surge. The maximum energy dissipated was a surprisingly low 35 joules. In 13 of 15 cases it was 1 joule or less.

I recently bought a plug-in protector that had ratings of 30,000A and 590J per MOV for each of the 3 MOVs - H-N, H-G, N-G. (It is not possible to get 30,000A at the protector, the rating just goes with a high energy rating.) It is very unlikely this protector will ever fail, which is one reason it has a connected equipment warranty.

Since this is a physics forum the technical details are that there are 2 reasons why the energy was so low. One is that at about 6,000V there is arc-over from service panel busbars to the enclosure. After the arc is established the voltage is hundreds of volts. Since the service enclosure is connected to the earthing electrodes this dumps most of the energy to earth. And at the service the neutral and ground are connected, also limiting the voltage on the house wiring.

The second reason is that the branch circuit impedance greatly limits the current (and thus energy) that can reach the protector. A surge is a very short event. A surge from lightning is over in less than 100 microseconds. That means the surge current has relatively high frequency elements, and the inductance of the wire is more important than the resistance.

Even more surprising than the 35J max energy was that the highest energies were for the smaller incoming surges (and shortest branch circuits). For some of the smaller surges the voltage limitation in the plug-in protector kept the voltage at the service panel below 6,000V, so arc-over did not occur.

So "absorb hundreds of thousands of joules"? Complete nonsense.

As long as claims are made subjectively, then a plug-in protector can do miracles. Once we add facts and numbers from the NIST, IEEE, and a long list of professionals, then a power strip is near zero protection.

More complete nonsense. The NIST and IEEE both say plug-in protectors are effective.

Where is any professional that says plug-in protectors do NOT work. Cite.

The only one who says plug-in protectors are NOT effective is westom.

A professional sales promoter for power strip protectors claims plug-in protectors will magically stop or absorb surges.

In case anyone didn't catch it, he is referring to me. My only connection with surge protection is I am using a couple protectors. If westom had valid technical arguments...

And it is only magic for westom. I have provided Martzloff's description of energy at a plug-in protector often. Apparently anything that does not conform to westom's belief in earthing is filtered out.

But a coax protector claim demonstrates why cable TV does not need any protector.

The IEEE surge guide says otherwise.

IEEE even gives numbers in a Standard called The Green Book entitled 'Static and Lightning Protection Grounding':

The IEEE Emerald book ("IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment") recognizes plug-in protectors as an effective protection device.

Yes, the IEEE says plug-in protectors can add protection. But only if a 'whole house' solution is implemented.

Complete nonsense, and in many cases backward.

Repeating what the NIST surge guide says:
"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."

And my comment:
"That is because the NIST surge guide suggests that most equipment damage is from high voltage between power and phone/cable/.. wires. Service panel protectors are likely to protect anything connected only to power wiring."

Most likely damage would probably be around the signal wiring at the equipment.
A rather limited investigation of damaged equipment that included Martzloff and an insurance company found in some cases just fuses blown or diodes burned out on the DC side of computer switch mode power supplies from a line surge.

The OP has garage door damage because 1) a surge entered due to no earthing, and 2) the surge found Earth destructively through that garage door.

Westom has the definitive answer from his Ouija board.

Sears seems to be familiar with the problem and seems to think it is unprotected control wiring. A surge on the power wiring is possible. As I said, the neutral and ground are not connected at the pole barn and the ground potential at the pole barn during an 'event' may be quite different from elsewhere.