On Thursday, May 19, 2016 at 8:55:38 AM UTC-4, email@example.com wrote:
Metal Oxide Varistor
Which doesn't diminish what it's purpose is and it's effectiveness.
But a new washing machine isn't the only electronics in the house.
Like Gfre says, best strategy is a whole house surge protector at
the panel or meter, with point-of-use type at eqpt that is also
connected to other lines, eg cable, phone, etc. If you're in a
situation where you can't put one on the panel, then point-of-use
at the washer can offer protection, but it's not the preferred
Few years ago I had several surge protectors get fried by a voltage
surge when a tree fell dropping the high tension wire on the low one.
Only item I lost was a microwave without a surge protector. Many years
ago we had lost a couple of unprotected TV sets now all electron stuff
in my house is protected. Also have usb's on all computers.
A surge expert at the NISThas written "in fact, the major cause of
[surge protector] failures is a temporary overvoltage, rather than an
unusually large surge." An example of overvoltage is crossed power wires
(as above). While MOVs can handle thousands of surge amps for the maybe
hundred microsecond duration of a surge they are rapidly burned out by
much longer lasting "overvoltage".
I've seen surge protectors (plug in ones) melt in an office. The computers without one popped their PSU's bulk caps.
The cause of this? Some workmen doing re-wiring confused the old UK with the new EU wiring colours and put two phases across a one phase outlet circuit.
A large insurance claim was made, then I replaced all the bulk capacitors at 50p each :-)
How does a man know when his wife is losing interest?
When her favorite sexual position is next door.
Pretty much internet garbage.
For instance (contrary to the link) if a MOV with a 1000J rating is hit
with 1000 - 1J hits, the cumulative rating is far greater than 1000J.
Look up a data sheet.
And the amount of energy that can make it to a plug-in protector over a
branch circuit is surprisingly low. A surge expert at the NIST
investigated how much energy can reach the MOVs. Branch circuits were
10m and longer, and surges coming in on power wires were up to 10,000A.
The maximum energy was a surprisingly small 35 joules. In 13 of 15 cases
it was 1 joule or less. Plug-in protectors with much higher ratings are
readily available. (There are a couple reasons the energy is so low, if
anyone is interested.)
(The surge of 10,000A is, for practical purposes, the maximum surge
exposure for a house. It is the result of a 100,000A lightning strike
(only 5% are stronger) to an adjacent utility pole in typical urban
And the IEEE surge guide (link in trader's post) describes how the
protected load can be connected to the incoming power, or connected
across the MOVs. In the latter case, if the MOVs fail the protected
equipment is disconnected. I believe protectors made now are required to
state if the protected load is not disconnected.
Some manufacturers have protected equipment warranties. They are
possible because the risk is much more limited than we expect (as
I don't expect any of my plug-in protectors, which have good ratings, to
On Thursday, May 19, 2016 at 6:03:02 AM UTC-4, philo wrote:
And where does it shunt those spike to? If not connected low impedance (ie
less than 10 feet) to single point earth ground, then it must shunt those
spikes elsewhere - such as destructively through adjacent electronics.
Protection is always about where energy dissipates. If a protector is adja
cent to an appliance, it can only protect by 'blocking' or 'absorbing' that
energy. How does its 2 cm part 'block' what three kilometers of sky could
not? It doesn't. How does its hundreds of joules absorb surges that can
be hundreds of thousands of joules? It doesn't. And does not have to. A
surge too tiny to destroy appliances can also destroy near zero plug-in pro
tectors. Then the naive consumer uses wild speculation to assume, "My prot
ector sacrificed itself to save my computer."
More robust protection already inside appliances protect those appliances.
Near zero joule protectors fail to even promote more sales.
A properly earthed 'whole house' protector does not 'block' or 'absorb' any
thing. It connects hundreds of thousands of joules harmlessly to what does
all protection - single point earth ground. Then even near zero plug-in p
rotectors are protected. Then near zero plug-in protectors can protect fro
m other and tinier anomalies.
Plug-in protectors are only useful if used in conjunction with properly ear
thed 'whole house' protection. Protection is always about where hundreds o
f thousands of joules are harmlessly absorbed. Any solution that does not
discuss that energy is best considered a scam.
MOVs are effective when connected low impedance (ie less than 10 feet) to w
hat actually does protection - single point earth ground.
Of course it doesn't Protectors do not work by "blocking" or "absorbing"
(But both service panel and plug-in protectors do absorb some energy in
the process of protecting.)
Of course not. Protectors do not work by "absorbing".
And as has been pointed out many times, in an expert investigation the
maximum energy that can make it to a plug-in protector is quite small -
35 joules and usually far less even with the worst probable surge on
power service wires.
But it is all too complicated for westom's simple minded beliefs.
And his stupid idea that appliances have intrinsic protection higher
than a plug-in protector
If they did, the manufacturer would list them under the UL standard for
surge protection - an advertizing advantage.
The maximum energy that can make it to a plug-in protector is quite
small - 35 joules, and usually far less, even with the worst probable
surge on power service wires. And no service panel protector.
It is westom's religiious belief in earthing.
Unfortunately the IEEE surge guide (starting page 30) explains that
plug-in protectors do not work primarily by earthing. But since that
conflicts with westom's religious belief he ignores it.
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