Do UPSes protect from surges under this scenario?

OK, under a typical scenario, you may have some equipment plugged into a UPS,
and when there is an electrical surge, it goes through the UPS's power cord to
the UPS and then gets stopped there. So it basically protects everything
"behind" the UPS from "outside" surges.

But do UPSes prevent surges that occur "behind" it from damaging other
connected equipment? Here's a scenario:

- some equipment is plugged into a UPS
- one of those components is a cable modem. (this is so that the cable modem
can still function during a power outage, as the cable line would still be
functional.) Let's say that the UPS does not have coax protection, so the
coax on the cable modem goes directly into the wall.

If a surge were to occur on the cable line (and this must be possible since
some surge protectors and UPSes offer coax protection), then it might go
through the cable modem, the cable modem's power cord, and then hit the UPS.
Would the UPS stop this surge from harming the other connected equipment?

 

[w_tom]

You are making so assumptions that even the UPS manufacturer
does not make. However he 'shorts' you enough facts so that
you will 'assume' as you have.

Will the UPS stop, block, or absorb what even 3 miles of sky
could not? Is that silly little one inch component going to
stop all that? Of course not. Effective surge protectors do
not stop, block, or absorb surges. They do as Ben Franklin
demonstrated in 1752. This is all explained in greater detail
in:
"Opinions on Surge Protectors?" on 7 Jul 2003 in the
newsgroup alt.certification.a-plus at
http://tinyurl.com/l3m9 or
"Power Surge" on 29 Sept 2003 in the newsgroup
alt.comp.hardware at
http://tinyurl.com/p1rk (changes to Google for worse means
technical discussion only starts at second group of posts
starting with post 11).
For many other technical sources:
"strange problem after power surge/thunderstorm" in
comp.dcom.modems on 31 Mar 2003 at
http://tinyurl.com/2gumt (changes to Google for worse
means technical discussion only starts at second group of
posts starting with post 6).

Even many cable companies are now teaching their installers
these installation requirements. A surge protector is not
protection. Furthermore cable requires no surge protector.
The cable must connect to surge protection before cable even
enter the house. No surge protector required because
connection is made using a copper wire. Same applies to every
incoming utility including telephone line (telco provides the
protector that is connected to protection) and AC electric.

The most common source of modem destructive surges seek
earth ground by striking wires on telephone pole, entering
building, passing through computer and/ or modem, and then
obtaining earth ground on cable. Even worse, the naive say
the modem was damaged; therefore the surge must have entered
on cable, damaged modem, then stopped.

If surge enters on modem and has no path to earth ground via
some other wire, then no complete electrical circuit exists.
No incoming AND outgoing path through a modem or computer
means no surge damage. Even worse, the plug-in UPS can make
surge damage to an adjacent computer even easier. Notice a
wire they would have you forget. That green wire bypasses UPS
protector to make a direct connection to motherboard and
chassis plate. Where is the protection to stop or block that
path?

Just another example of what the UPS manufacturer forgot to
mention to get you 'to assume' mythical protection.
Protection is about earthing every utility wire to a single
point ground - either by direct wire of via a surge protector
- before that wire can enter the building.

In the meantime, if anything in your building is creating
destructive surges, then the first thing destroyed would be
the surge generator. Also destroyed are smoke detectors,
dishwasher, dimmer switches, clock radio, etc. Where are
these destructive transients from household appliances? Why
are we not trooping to the hardware store every week to
replace these damaged appliances? The internal generated
surge is a myth. One way to suspect a myth: they don't even
provide numbers. Notice the so many numbers also provided in
those previous discussions.

Surge protection is based upon what Ben Franklin
demonstrated in 1752 and has been routinely installed without
damage from direct strikes since the 1930s. Read those
previous discussions. A surge protector is only as effective
as its earth ground.

void@no.spam.com wrote:

OK, under a typical scenario, you may have some equipment plugged
into a UPS, and when there is an electrical surge, it goes through
the UPS's power cord to the UPS and then gets stopped there. So
it basically protects everything "behind" the UPS from "outside"
surges.

But do UPSes prevent surges that occur "behind" it from damaging
other connected equipment? Here's a scenario:

- some equipment is plugged into a UPS
- one of those components is a cable modem. (this is so that the
cable modem can still function during a power outage, as the cable
line would still be functional.) Let's say that the UPS does not
have coax protection, so the coax on the cable modem goes directly
into the wall.

If a surge were to occur on the cable line (and this must be
possible since some surge protectors and UPSes offer coax
protection), then it might go through the cable modem, the cable
modem's power cord, and then hit the UPS. Would the UPS stop this
surge from harming the other connected equipment?

 

[Ed Nielsen]

You could always place a surge suppresser such as
this<http://www.cencom94.com/gpage.html8.html> at your groundblock,
which would help. But nothing will give you 100% protection. Went to a
house once where the TV set in a detached building (workshop) fried.
The surge created during that event fried the surge protector, which had
a CATV drop connected to it. The surge traveled up the drop to the
house, where it proceeded to fry the drop amp and melt the coax inside
the wall and ceiling 'til it got to the groundblock, where it went to
ground.

True, that was just a surge strip, but I don't see why there isn't the
same potential with a UPS.


CIAO!

Ed

void@no.spam.com wrote:

OK, under a typical scenario, you may have some equipment plugged into a UPS,
and when there is an electrical surge, it goes through the UPS's power cord to
the UPS and then gets stopped there. So it basically protects everything
"behind" the UPS from "outside" surges.

But do UPSes prevent surges that occur "behind" it from damaging other
connected equipment? Here's a scenario:

- some equipment is plugged into a UPS
- one of those components is a cable modem. (this is so that the cable modem
can still function during a power outage, as the cable line would still be
functional.) Let's say that the UPS does not have coax protection, so the
coax on the cable modem goes directly into the wall.

If a surge were to occur on the cable line (and this must be possible since
some surge protectors and UPSes offer coax protection), then it might go
through the cable modem, the cable modem's power cord, and then hit the UPS.
Would the UPS stop this surge from harming the other connected equipment?

 

[Boris Mohar]

On Mon, 20 Dec 2004 03:47:53 -0500, void@no.spam.com wrote:

Why do so many people think that you are wrong?

http://groups-beta.google.com/groups?q=w_tom+wrong&start=10&hl=en&safe=off&

Because they are not well grounded in basic electrical theory.

--

Boris Mohar

 

[Rick Merrill]

void@no.spam.com wrote:

OK, under a typical scenario, you may have some equipment plugged into a UPS,
and when there is an electrical surge, it goes through the UPS's power cord to
the UPS and then gets stopped there. So it basically protects everything
"behind" the UPS from "outside" surges.

But do UPSes prevent surges that occur "behind" it from damaging other
connected equipment?

No, it does not protect the protected from one another.

There are a few high end systems that have 'three way protection' that
may protect the equipment from one another. - RM

 

[Bob Haar]

On 2004/12/31 9:18 AM, "Rick Merrill" <RM@THROW.net> wrote:

void@no.spam.com wrote:

OK, under a typical scenario, you may have some equipment plugged into a UPS,
and when there is an electrical surge, it goes through the UPS's power cord
to
the UPS and then gets stopped there. So it basically protects everything
"behind" the UPS from "outside" surges.

Not all UPS devices do this. Check the specs for the equipment you have (or
will purchase). Look for over-voltage protection and noise filtering. The
only thing that some simple UPSs will do is to switch to backup battery
power when the line voltage drops below some threshold.

But do UPSes prevent surges that occur "behind" it from damaging other
connected equipment?

No, it does not protect the protected from one another.

There are a few high end systems that have 'three way protection' that
may protect the equipment from one another. - RM

It might be less expensive to put each piece of suspect equipment on its own
UPS.

What kind of equipment are you worried about creating a voltage surge. I
would only expect that from a large inductive load, like a motor.