Plugging 1 Surge protector into another?


B

Bill

Is there any harm or benefit to electronics fed by a surge protected
extension strip that is getting plugged into an already surge protected
outlet?

I know capactors in parallel add up in theory, but I am not sure how it work
in practice.
 
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R

Ralph Mowery

Is there any harm or benefit to electronics fed by a surge protected
extension strip that is getting plugged into an already surge protected
outlet?

I know capactors in parallel add up in theory, but I am not sure how it work
in practice.

It will not harm anything. You will gain more protection.
 
L

lucky

Bill said:
Is there any harm or benefit to electronics fed by a surge protected
extension strip that is getting plugged into an already surge protected
outlet?

I know capactors in parallel add up in theory, but I am not sure how it work
in practice.

This is not a scientific answer but I have some evidence that the other
poster here could be maybe not be right to suggest plugging 1 into
another one. I'd advise investigating belkin's web site or somewhere
else on the web to independently confirm. I am no electrician.

This thread was on a tivo board regarding plugging stuff into each other
and again, is just one of 1 million sources or info. I am no expert,
just want people to find the right info or be informed of other answers.

http://www.tivocommunity.com/tivo-vb/showthread.php?s=&threadid=147890

my 2 cents: My personal gut feeling is just get an extension cord and
don't put 2 together.
 
L

larrymoencurly

Bill said:
Is there any harm or benefit to electronics fed by a surge
protected extension strip that is getting plugged into an
already surge protected outlet?

No harm if both surge protectors contains only MOVs and capacitors,
but if either contains an L-C filter (EMI filter -- blocks noise but
also supposedly helps surge protection, too) and the other contains
either just a capacitor or also an L-C filter, then I've read that the
right combination of two filters can cause a big peak in the frequency
response, allowing noise and surges in a certain frequency band of
noise pass through a lot easier than signals of other frequencies.
www.epanorama.net or www.cor.com should have more information about
this, but I've seen some ATX PSUs with two EMI filters in them, one on
the big circuit board, a second one either there or at the AC plug (in
a metal container or on a small circuit board -- Enermax, Antec).
 
J

JAD

You could be overloading the single line and could put a dangerous strain on the wall socket, if your loading it up with heavy
appliances. You will gain no 'extra' protection.
 
E

Ed Medlin

Bill said:
Is there any harm or benefit to electronics fed by a surge protected
extension strip that is getting plugged into an already surge protected
outlet?

I know capactors in parallel add up in theory, but I am not sure how it work
in practice.
The main problem here is that your wall socket may not be up to it. One
suggestion that does work however, is to use a UPS and you can then plug two
or three strips into it since it will only draw power enough to keep the
battery charged, which is not a lot. This only applies to the "protected"
outlets on the UPS and not the unprotected ones.


Ed
 
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G

Gary Tait

Is there any harm or benefit to electronics fed by a surge protected
extension strip that is getting plugged into an already surge protected
outlet?

I know capactors in parallel add up in theory, but I am not sure how it work
in practice.

I don't know, but all of the documentation on the ones I bought only
guarantee if they are directly plugged into a wall recepticle.
 
R

Ray

The main problem here is that your wall socket may not be up to it. One
suggestion that does work however, is to use a UPS and you can then plug two
or three strips into it since it will only draw power enough to keep the
battery charged, which is not a lot. This only applies to the "protected"
outlets on the UPS and not the unprotected ones.

Don't do that. Just about every UPS I've seen comes with an explicit
warning not to. It may appear to work just fine when the power is on and
the UPS isn't actually doing anything but when the power goes out and the
UPS' inverter kicks in it'll shut off due to the overload. If you're not so
lucky (or it's a poorly designed UPS) it'll shut off and come back on as the
load fluctuates and send a fairly nasty surge into your equipment (which
your surge protectors may or may not stop.

Also what makes you think that the UPS will "only draw power enough to
keep the battery charged"? If you have a bunch of devices plugged into it
then it will have to draw enough to supply them AND a bit more to keep the
battery charged.
 
W

w_tom

First, the surge protector does not even claim to stop,
block, absorb, or filter destructive surges. Will it stop
what miles of non-conductive air could not? Of course not.
But that is the myth: that a surge protector will sit between
transistor and surge - to protect transistor.

2) A surge protector is only as effective as its earth
ground. That is all it does. A surge protector is not surge
protection. A surge protector is only effective when it makes
a less than 10 foot connection to surge protection. To sell
their overpriced, ineffective products, the plug-in protector
forgets to mention earthing - the one and only essential
component in a surge protection system.

3) Your appliances already contain effective protection.
Any protection that works at the appliance is already inside
that appliance. If those $0.10 components inside a $20 or $50
power strip were effective, then those components are already
inside that appliance.

But internal protection is predicated on a principle that
destructive surges will be earthed before they enter a
building. Its called 'whole house' protectors. If not earthed
at the service entrance, then destructive surges will
overwhelm protection already inside the appliance. Effective
protectors connect less than 10 feet to central earth ground -
and are called 'whole house' protectors. That is protection
at less than $1 per protected appliance - that actually
provides protection. Compare that to $10 and $40 per
appliance for ineffective plug-in protectors.

4) Another has properly noted a problem with any power strip
protector on the UPS output. When in battery backup mode,
plug-in UPSes output sine waves that really are more like
noisy square waves. For example, this UPS outputs two 200
volt square waves with a spike of up to 270 volts between
those square waves. That is called 120 VAC to a computer. No
problem for electronics because electronic power supplies are
so resilient - contain substantial internal protection.

But a spiky UPS will either damage the UPS when in battery
backup mode (when the electricity is far dirtier), or will
slowly degrade MOVs inside that power strip into degradation.
It is why surge protectors must not be on UPS outputs. Again
the power strip surge protector does nothing more than enrich
its manufacturer - in part because they routinely forget to
mention much of what is posted here. If they mentioned
earthing, then sales would decrease. Better to lie by not
telling the 'whole' truth.

5) Most important feature in every acceptable power strip is
the 15 amp circuit breaker. That circuit breaker means
multiple items may be plugged into one power strip - safely.
Too much current draw will trip the breaker - the essential
safety feature. Such power strip sell for as little as $3 in
Walmart and Home Depot. However ineffective surge protectors
often remove that circuit breaker, install some $0.10
components, then sell for $10 or $40. They remove an
essential protector in any power strip - the circuit breaker?
Yes. And again, this is forgotten by those who recommend
those ineffective products.

Wall receptacles for the most common 120 VAC plug is 15
amps. Often powered by 20 amp circuit breakers. No problem
if only one appliance is plugged into that 15 amp receptacle.
But when multiple appliances share the same plug, then a power
distribution strip should have that all so important 15 amp
circuit breaker - so that the receptacle is not overloaded.

6) Neither plug-in UPS nor power strip even claims
protection from destructive surges. So that you don't ask
embarrassing questions, don't mention which types of surges
they protection from, AND avoid all mention of the most
important feature - earth ground. No mention of earthing
implies a surge protector is not claiming effective
protection. No earth ground means no effective protection.

Technical concepts underlying these principles were
discussed in a previous newsgroup alt.certification.a-plus
entitled "Opinions on Surge Protectors?" on 7 Jul 2003 or at
http://tinyurl.com/l3m9

Effective 'whole house' protectors are sold even in Home
Depot as Intermatic EG240RC and IG1240RC or Siemens QSA2020.

No earth ground means no effective protection. By chaining
power strip surge protectors together, you are only making the
problem worse - adding more length to an already too long
connection to earth ground. Furthermore, consider other
incoming surge paths as discussed previously in that above
newsgroup. A surge protector is only as effective as its
earth ground - which undersized, ineffective plug-in
protectors must have you not learn to sell their overpriced
product.
 
C

Conor

It will not harm anything. You will gain more protection.
How? If the second surge protector goes, it'll most likely take out the
first one as well. End result is the same as getting a single surge
protector with more sockets.
 
R

Ralph Mowery

How? If the second surge protector goes, it'll most likely take out the
first one as well. End result is the same as getting a single surge
protector with more sockets.

It all depends on how the surge protector is made. Surge protectors are
made to 'go out' or blow to protect the device plugged into them. The
simpler protectors have a device called a MOV across the line. The beter
ones have 3 MOVs one across the line and one from each side of the line to
the ground, maybe some other components as well like the Isobars I use. If
one is plugged in after the other one you in effect double the ammount of
Joules the devices can withstand . You may not get that much added
protection, but it will be some. The whole object is to blow out the surge
protector and protect the more expensive device downline. The MOVs can
withstand some surges without being destroyed, but they will be weakened.
At some time they will become ineffective . The more inline , the beter the
chances of atleast one surviving to protect the equipment.

The whole point is that it may not provide hardly any more protection, but
it will not harm anything.
 
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W

w_tom

If surge protectors were designed "to 'go out' or blow to
protect the device plugged into them", then why do MOV
manufacturers provide all those charts on MOV life
expectancy? Why bother if the MOV is destructive protection?
When an MOV fails, it operates in a region why off the chart -
because it was grossly undersized. Properly sized surge
protectors (that also cost less money) are not destroyed by
surges.

Many plug-in protectors are so grossly undersized as to be
damaged by a surge not sufficient to even damage the adjacent
appliance! As noted previously, all appliances contain
effective protection. Protection sufficient that a surge, too
small to damage the appliance, still damages the grossly
undersized surge protector.

How to increase sales. First avoid anyone who studies
component datasheets - who first learns the engineering.
Second, make sure the surge protector is so grossly undersized
as to even be damaged by a trivial surge. Then the ill
informed human recommends that surge protector to friends and
buys more.

Nonsense. The effective surge protector provides protection
without any indication. Damage due to a surge - either to
appliance or surge protector - means the human has failed to
learn basic knowledge.

MOV datasheets are quite blunt. They show how many surges
the MOV will survive until 'degraded'. 'Degraded' - not
'damaged'. Effective surge protectors eventually 'degrade'.
Any surge protector that is 'damaged' was grossly undersized -
as well proven by those datasheets - and due to a human who
did not learn fundamentals.

One can spend $10 or $50 per protected appliance, not have
effective protection, and also suffer surge protector
'damage'. Or one can install 'whole house' protectors that
are properly sized, remain functional after many surges, and
cost about $1 per protected appliance.

Even dollar numbers demonstrate myth of plug-in protectors
such as that Isobar - that also forgets to claim protection
from the destructive type of surge. Why? No earth ground
means no effective protection. So instead, that Isobar avoids
all mention of earthing to maintain sales.

Instead, they would even have some believe those MOVs are
the protection. Nonsense. Protection is earth ground. Those
MOVs need only be properly sized to 'shunt' to earth -
temporarily act like a wire - and remain intact - per MOV
manufacturer datasheets. Effective surge protectors are not
sacrificial devices. A surge protector damaged by a surge was
grossly undersized, typically overpriced, and simply not
effective - as even manufacturer data sheets demonstrate.

In the meantime, chaining those protectors does nothing but
enrich the manufacturer. Some foolishly think those
protectors are stopping, blocking, or absorbing surges. Again
nonsense. They are called shunt mode devices for good
reason. The surge protector is only as effective as its earth
ground - which is why central earth ground is less than 10
feet away from an effective protector.
 
B

Billy_Bat

w_tom said:
If surge protectors were designed "to 'go out' or blow to
protect the device plugged into them", then why do MOV
manufacturers provide all those charts on MOV life
expectancy? Why bother if the MOV is destructive protection?
When an MOV fails, it operates in a region why off the chart -
because it was grossly undersized. Properly sized surge
protectors (that also cost less money) are not destroyed by
surges.

Many plug-in protectors are so grossly undersized as to be
damaged by a surge not sufficient to even damage the adjacent
appliance! As noted previously, all appliances contain
effective protection. Protection sufficient that a surge, too
small to damage the appliance, still damages the grossly
undersized surge protector.

How to increase sales. First avoid anyone who studies
component datasheets - who first learns the engineering.
Second, make sure the surge protector is so grossly undersized
as to even be damaged by a trivial surge. Then the ill
informed human recommends that surge protector to friends and
buys more.

Nonsense. The effective surge protector provides protection
without any indication. Damage due to a surge - either to
appliance or surge protector - means the human has failed to
learn basic knowledge.

MOV datasheets are quite blunt. They show how many surges
the MOV will survive until 'degraded'. 'Degraded' - not
'damaged'. Effective surge protectors eventually 'degrade'.
Any surge protector that is 'damaged' was grossly undersized -
as well proven by those datasheets - and due to a human who
did not learn fundamentals.

One can spend $10 or $50 per protected appliance, not have
effective protection, and also suffer surge protector
'damage'. Or one can install 'whole house' protectors that
are properly sized, remain functional after many surges, and
cost about $1 per protected appliance.

Even dollar numbers demonstrate myth of plug-in protectors
such as that Isobar - that also forgets to claim protection
from the destructive type of surge. Why? No earth ground
means no effective protection. So instead, that Isobar avoids
all mention of earthing to maintain sales.

Instead, they would even have some believe those MOVs are
the protection. Nonsense. Protection is earth ground. Those
MOVs need only be properly sized to 'shunt' to earth -
temporarily act like a wire - and remain intact - per MOV
manufacturer datasheets. Effective surge protectors are not
sacrificial devices. A surge protector damaged by a surge was
grossly undersized, typically overpriced, and simply not
effective - as even manufacturer data sheets demonstrate.

In the meantime, chaining those protectors does nothing but
enrich the manufacturer. Some foolishly think those
protectors are stopping, blocking, or absorbing surges. Again
nonsense. They are called shunt mode devices for good
reason. The surge protector is only as effective as its earth
ground - which is why central earth ground is less than 10
feet away from an effective protector.

Thanks, w_tom!
I used to work for an electrical engineer, and I remember him saying
something about the typical 6 outlet surge protector being a waste.
Insufficient protection, and a false sense of security, and then he would go
into a technical explanation, similar to the above. <g>
 
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W

w_tom

Your telco connects to overhead wires everywhere in town. Do
they disconnect for thunderstorms? Do telco and 911 operators
remove headsets when storms approach? Of course not.
Effective 'whole house' type protection has been routine and
that effective since before WWII. However we don't install it
in residences. Starting in 1970s, all homes required surge
protection. The most critical component being a single point
earth ground. One is typically available in every 'under
construction' home at so little cost - called Ufer grounding.
And yet still we don't install such protection 30 years later.

Homeowners must learn and install 'whole house' protectors
on AC electric because that is not yet required by any
building code and that is the source of most electronics
damage - even to computer modems. Principles so well proven
that even a telco $multi-million computer connected to
overhead wires everywhere is not damaged. Protector that
costs about $1 per home appliance. Protector that is only as
effective as its earth ground. Protector that all homeowners
now require and yet few install.
 

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