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w_tom
 
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The power strip and circuit breaker (or fuse) will not
interact with the power wedge. In fact, any power strip that
does not have the 15 amp circuit breaker should be removed
from premises as a threat to human safety.

Power strip surge protector are cheap power strips with a
few $0.10 parts added. The active component (MOV) remains
totally inert until 120 VAC exceeds something like 300 volts.
Are you seeing 300+ volts on you AC main? If not, all power
strips remain inert. Meanwhile, spend tens of dollars to
convert a cheap power strip into a surge protector using $0.10
parts. Better is to save money; use the cheap power strip.

The power strip will provide up to 15 amps to the power
wedge (or anything else). Circuit breaker protects humans
from making stupid (and therefore dangerous) mistakes. To the
power wedge, cheap power strip looks like power is coming
directly from the wall receptacle.

Agent_C wrote:
Joe Sensor wrote:
What exactly is wrong with a "cheap power strip"?


I just want a passive switch; nothing more. I'm uncertain how the fuse
and surge protection circuitry in a 'cheap power strip', or even an
expensive one, would interact with the PowerWedge.

A_C

  #82   Report Post  
w_tom
 
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APC makes that external surge protector stipulation in a
list of exceptions. They make a warranty claim. Then include
numerous 'fine print' exceptions so that a claim need not be
honored. Chains of protectors adversely affect protection
only because those protectors add even more wire to earth
ground. No short connection to earth ground means no
effective protection from the typically destructive transient.

All being irrelevant to Agent_C's original post. Since a
power strip (with or without surge protector) does nothing
(remains inert) when voltage is well below 300 volts, then
either power strip will work just like a power switch.

Steve Urbach wrote:
Many $9.oo strips claim some surge protection :^)

Note APC protection plan states that it is void if you use external
surge protectors on either the line or load as they claim that it is
possible for them to interfere with each other resulting in poorer
protection than either one could supply.

Make sence if neither sees the full surge to initiate full clamping.

  #84   Report Post  
Pooh Bear
 
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Mike Rivers wrote:

If you
want to use an outlet strip, take it apart (which might require a
drill or file on an outlet strip that's too cheap to be held together
with screws) and clip out the MOV. It's a round thing with two leads,
about the diameter of a nickel.


Is it normal for US socket strips to contain MOVs ?

Over here it isn't. You have to pay more for that type.

Btw - just bought 2 UK 4 way strips at the local supermarket for a total
of £1.75 - USD ~ 3.20.

Graham

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Arny Krueger
 
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"Pooh Bear" wrote
in
message
Mike Rivers wrote:

If you
want to use an outlet strip, take it apart (which might
require a drill or file on an outlet strip that's too

cheap
to be held together with screws) and clip out the MOV.

It's a
round thing with two leads, about the diameter of a

nickel.

Is it normal for US socket strips to contain MOVs ?


No. It is more common than it was, but its usually part of a
scheme to extract a higher price from the consumer.

Over here it isn't. You have to pay more for that type.


Ditto.

Btw - just bought 2 UK 4 way strips at the local

supermarket
for a total of £1.75 - USD ~ 3.20.


I think Home Depot still sells 2-packs of 6-way outlet
strips for about 5.00 USD.




  #87   Report Post  
w_tom
 
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The normal MOV failure mode is not to open, fail shorted, or
vaporize. Catastrophic failure occurs when the MOV is
installed as not intended by its manufacturer. A condition
known as catastrophic failure due to a grossly undersized
protector. Manufacturer provides life expectancy data
sheets. MOVs degrade according to number and strength of
transient current.

However, when selling ineffective MOV protectors to a naive
public, some companies undersized them. Then when a grossly
undersized protector fails (and when protection inside the
appliance actually protects the appliance), then the human
says, "The protector sacrificed itself to save my computer."

Effective protectors degrade. Grossly undersized protectors
are undersized to be sold at excessive profits; so that a
human will recommend it and buy more. Take a $3 power strip
from Home Depot or Wall Mart. Install some $0.10 components.
Sell the modified $3 power strip for $15 or $50 as a surge
protector. A naive public will suffer catastrophic protector
failure - a completely useless protector - then buy more and
recommend the overpriced and undersized device to friends.

Protectors might be placed either on the input or output of
the conditioner. On the input, a shunt mode protector would
simply provide a destructive transient with more wires into or
around the conditioner. If the conditioner is working as
intended, then a power strip protector connected to
conditioner output would do nothing. The 120 volt power strip
protector should ignore everything until voltages exceed the
let-through voltage (about 300 volts). "Should" because power
conditioners may not stop or eliminate those typically
destructive 300+ volt transients.

If the power strip is connected to a typical computer grade
UPS, well, those UPSes output excessive voltage spikes when in
battery backup mode. For example, this 120 volt UPS outputs
two 200 volt square waves with up to a 270 volt spike between
those square waves. Spikes that do not harm computers. But
spikes may degrade a power strip protector or cause
conditioner component failure. (Note the word degrade; not
MOVs that short, open, or vaporize.) Protectors are not
intended for protection from repetitive spikes as demonstrated
by MOV manufacturer's chart described in 1st paragraph.

Is this UPS output destructive? Yes to some small electric
motors and power strip protectors. But internal computer
protection would make that 200+ volt spike completely
irrelevant. It's 'dirty' electrical output during battery
backup mode is why power strip protectors should not be placed
on UPS outputs.

Last few pictures demonstrates how to remove MOVs from a
power strip. Note the caption. MOVs are removed and the 'OK'
light still says the power strip is OK:
http://www.zerosurge.com/HTML/movs.html

Mike Rivers wrote:
I suspect that one reason why they might want you to hang a surge
suppressor on it is because when they're suppressing, they shunt
current that might otherwise be drawn by the connected equipment when
it gets more than its rated working voltage. This would put an
excessive load on the UPS/Conditioner. Also, although the general
failure mode of a MOV surge supressor is open (giving no protection
once it's failed) they've been known to fail in the shorted (or more
correctly, low resistance) state, which would put undue load on the
source.

I don't think it has to do with chaining anything, nor do I see a
problem with an external circuit breaker in line with the load. If you
want to use an outlet strip, take it apart (which might require a
drill or file on an outlet strip that's too cheap to be held together
with screws) and clip out the MOV. It's a round thing with two leads,
about the diameter of a nickel.

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