Well, a big flaw in that thinking of mine. The pdf file someone
"These outlet protectors
usually have an LED which
informs the user that the protector is
no longer working and must be
replaced. Unfortunately, nature does
not always cooperate with this
THIS IS THE IMPORTANT PART:
"Most lightning strokes are
not just singular, but consist of several
strokes spaced milliseconds apart. The
electronic equipment is likely to be
damaged before the homeowner
replaces the protector."
I shoudl have bought a better one, although I don't know if the
Intermatic for 130 or 160 is really better.
Not always as bad as it sounds, many MOV's just become a dead short and
blow the breaker. I've also opened up some protectors and added a
couple more MOV's parallel. Radio Little Run Down Building used to have
two kinds of 130V MOV's, of course get the bigger ones if you have the
UL1449 (since 1998) requires a disconnect for overheating MOVs. The
protected load can be connected across the MOVs, so it is disconnected
with the MOVs. That way the protected load does not loose protection
(although it will loose power). Some suppressors have warranties for
protected equipment. Plug-in suppressors with a warranty are likely
wired this way. (Obviously you can't do this with service panel
Or the protected load can be connected ahead of the MOV protection. The
protected load would then stay powered without protection. According to
the IEEE surge guide, plug-in suppressors wired this way now are
required by UL to be identified.
Anything with a UL label built since 1998 has built in disconnects for
IMHO changing a suppressor violates the design and is a safety hazard.
There are a lot of things I would fix or change. A suppressor is not one
I did see a change inside some equipment where they put a fuse before
the MOV. Would this have anything to do with new code? (It is inside
the equipment) If I were to make one extra safe, I'd put a few fuses in
series with a MOV parallel after each fuse.
A MOV parralell across the hot and neutral is pretty basic stuff and
doesn't get much simpler. But yes, if you don't know basic electronics
maybe you shouldn't do it. Putting in a larger rated MOV or several
MOV's in parallell is like what many people do by plugging a surge
suppressor into another surge protector for better protection. Or
plugging in a multi outlet strip with surge protection into a surge
protector and then to the outlet. Any dangers with those idea's too?
The disconnects, specifically in surge suppressors (not 'equipment'),
are to prevent the suppressor from being a fire hazard. The disconnects
are likely near the MOVs to respond at least partly to MOV heat. A
normal fuse may work. But the whole thing, in a competent design,
provides overheating protection while not disconnecting until the MOVs
are failing. It is an engineered product.
I used to use a homemade plug-in surge suppressor. It included a fuse. I
decided it was not as safe as I wanted.
For best device life you want the surge shared by the parallel MOVs.
Since MOVs are not precision devices that is not likely to happen unless
the MOVs are matched, as from the same batch. If one MOV takes most of
the surge hit (likely in a random pairing) you may not get much
advantage from the second MOV. The first MOV can die (shorted) while the
second MOV has much of its life left. It is basic electronics.
UL does not intend for them to be daisy chained. You are not likely to
find a manufacturer that would say it is OK (and it is probably
explicitly prohibited in the manufacturer instructions).
As above, daisy chaining does not necessarily work the way you expect.
You can get plug-in suppressors with high ratings for not much money. I
don't really see a reason to take chances on compromising surge
protection or fire protection.
Yes, they got pretty mad at me in sci.electronics.repair when I
suggested that I would repair my whole-house suppressover if the MOVs
My theory was that would justify my buying an expensive one, if I knew
I coudl keep it running, but they didnt' like that and no one defended
On Sun, 13 Mar 2011 04:50:11 -0700 (PDT), " email@example.com"
You're right. I didn't buy the wrong thing!
Accordign to http://www.apsllc.net/Cooper%20Power/Line/Aug97.pdf
To eliminate this problem (the one I quoted in my preivous post),
grade surge arrester mounted at the
service entrance absorbs the bulk of
the energy from lightning surges,
allowing the local surge suppressor to
work properly. A durable, high-energy
service entrance arrester helps ensure
that other protective devices within
the house continue to work for years.
The service entrance surge arrester also
protects the wiring and electromechanical
loads (washers, dryers,etc.) in the home
from lightning damage.
Well my cheap one is whole house, so maybe it's somewhere in the
If BGE has a utility grade surge arrestor for my house, I don't know
how much they would charge.
It's at least as well protected with the switched turned off as with
the switch turned on because the surge protection components are still
connected to the AC lines.
But if a storm is pending or you'll be leaving your home, unplug
everything connected to the computer, even the monitor, printer,
modem, and TV cable.
Turning them off doesn't do much for lightning/surge suppression if
anything. Ive never lost a 'puter to lightning but I have lost a TV
and several piece of test equipment I left plugged into my work
bench..... They were turned off .
As an electronics repairman over the years I have repaired many
lightning damaged devices where all I had to do was replace the MOV.
While I cant say with absolute certainty that this protected the
device as I also have may crispy fried circuit s that had lightning
protection I would say that the evidence I have seen leans in that
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