We had a near lightening strike that sent a surge though the power lines.
Not sure where the hit was, but I did have some damage.
My wife called me at work after a thunderstorm and said she saw a big red
ball in the driveway and then some of the lights went out. The doorbell
rang and would not stop ringing. I told her to take a wire off the chimes
and they stopped, but a breaker was tripped and would not reset. The bell
button has a diode in it and that may have taken the hit.
When I got home, I took the two wires off of the breaker and it still did
not reset so I replaced the breaker. One of the circuits was OK, the other
had a short and tripped the breaker. Since it was not getting dark and it
was still raining, the hunt would wait a day. Next day, I went out to the
(detached) garage and found an X-10 module I use to control an outdoor light
was blown apart and burnt. The plastic cover was gone, the insides were
soot covered. I'm wondering if the jolt came in that way or out, it was
the furthest away from the electric panel.
I'm going to replace the receptacle it was plugged into also. I've not
pulled that out yet, but I'm not taking any chances. Once replaced. I'll
hook the wire back to the breaker.
Losses were: HD TV, Surround sound receiver, X-10 module, computer router,
The good news is: I now have a 47" TV with far better picture than my 5
year old 32" and a better sound system.
More stuff is on surge protectors too.
Out of curiousity, is there a lightning arrester on service entrance?
They can help before get to the individual protectors.
In TN some years ago, took nearly everything in the house behind a
friends including dislodging about half of the brick veneer off rear of
two-story mini-McMansion...it's pretty amazing what it can do, indeed.
Nothing on the entrance. I'm debating whole house surge protection.
Initial cost is about $150, then a $6 monthly charge. Over the years I'm
still ahead, but. . . . .
OTOH, I'd not have a new big screen TV for a while without the lightening.
What's the $6 charge for?
Good a time as any to ask if this is what I want when I get around to
5yr warranty- 400Amp or less panel- $10,000 warranty
There's your silver lining- I think I'll put it off until something
gets my 10yr old TV.<g>
I've got all my electronic stuff on surge protectors and APC's. Don't
like the idea of a whole house protector as I've seen them get knocked
out and then you are at the mercy of getting in an electrician.
Also power company is reticent to take any blame even when it is their
fault because they saved money in tree trimming. And, with a $500
insurance deductible plus value proration, insurance company is a PITA
I know they don't work well enough every time but . I had my whole
house lightning protectors blown out of there box, nothing else was
harmed. I hate to think of the damage that would have been done if I
hadn't had them
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
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.
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.
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
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.
The extreme explosive sound when lightning struck my house six years
ago was something to experience. The base of my cordless phone was
destroyed, a surge protector in the computer room was destroyed (the
computer was okay except for the modem), a small surge protected plug
tap was damaged and the sparks blew out of for a foot or so and the
smell of burnt bakelite or whatever it was made of permeated the
kitchen. Other than that, everything else was okay although later on
that summer the transformer on the service pole started to smoke and
short out and had to be replaced so it most likely was damaged from
the same storm.
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