jim hardy said:
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.
