Re: Surge protection without grounded plugs


"w_tom" <w_tom1@xxxxxxx> wrote in message
news:1190653812.895762.291430@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
So what does the typically destructive surge seek? Earth ground.
Why must those earthing wires be so short? Well let's finish the
math. An AC wall receptacle is maybe 50 feet from the breaker box.
IOW it is maybe 0.2 ohms resistance. But the same wire is something
like 130 ohms impedance to the surge. What happens when a power strip
protector attempts to earth a trivial 100 amp surge via neutral wire?
13.000 volts difference. Will a surge use the 13,000 volt wire to
obtain earth? Of course not. It will also find other path to earth
via furniture, wall paint, baseboard heater, etc. The AC receptacle
ground is safety ground. But the destructive surge, if permitted at
the appliance, will find every path to earth - destructively.

The effective protector earths before that surge gets anywhere near
to appliances.

Your MOVs protectors do protect from the type of surge as exampled.
Do appreciate that it is not the type of surge that typically causes
damage. Surge that damaged electronics seeks earth ground. Its
energy must be dissipated somewhere. If not dissipated in earth, then
it dissipates destructively via household appliances in a path to
earth. If the MOV protector is grossly undersized as is common with
many plug-in protectors, then even these scary pictures can result:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING%20SURGE%20SUPPRESSOR%20FIRES.doc

I appreciate the spirit of your reply. But you have completely
ignored some critical facts. Typically destructive surge seeks earth
ground. It may be completely ignored by your three MOV protector. Or
your three MOV protector may even give the surge more paths to find
earth, destructively, via adjacent appliances.

The surge you have discussed is typically made irrelevant by
protection already inside appliances. Anything that a power cord
protector might accomplish is already inside appliances. What can
overwhelm protection inside appliances? A type of surge that seeks
earth ground. We earth this typically destructive surge before it can
enter the building - and with only one properly sized protector. Then
massive energy of this far more destructive surge is dissipated in
earth - does not find destructive paths to earth via household
appliances.

What provided the protection? What dissipates surge energy? Does
that silly little MOV absorb such surges? Of course not. Surge energy
must dissipate somewhere. Earth is where surge energy is dissipated.
No earth ground means no effective protection from a type of surge
that typically cause appliance damage.

Appreciate that I have understood earthing for probably longer than
you have existed. You are even confusing low resistance earthing with
low impedance. Appreciate why a connection to earth ground must be
'less than 10 feet' - and other critical factors. If you don't
understand those numbers, then you have not yet learned the many
functions performed by earthing.

Of course this is well beyond what the OP was asking. Chances are
the building is so old as to not even have any earthing - a major
human safety problem as well as making a surge protector completely
ineffective.


I guess your the god of earth ground? Please... nots not get into some silly
fight over such an issue. I believe you are confusing safety with surge
protection. Surge protectors are not decides with saftey in mind but only to
protect the equipment involved to some degree.

I agree that safety is an issue and I agree its best to have earth ground.
Hell, maybe they would put a piece of rebar driven into the ground where
every recepticle is along with some type of external surge protection for
the whole house? But the fact of the matter is that is that many devices
use only hot and netural without any earth ground even whe its available(go
look at your toster and any small appliance).

In any case my point is that surge protectors themselfs do not need earth
ground. I never said it was a good idea not to have them but you claimed
they are completely ineffective without earth ground and this is simply not
the case. They do exactly what they were designed to do with out any earth
ground... infact if you open one up, at least in a cheap one, you will not
see the surge protection circuitry use earth ground at all.

The only thing I really disagree with you on is that surge protectors, and
here I'm implicitly refering to the common ones that the average person can
buy, do not need earth ground to protect against your average surge and
minimize damage to the device connected. It greatly minimizes the damage to
devices connected compared to not having anything at all(Even if you have
earth ground).

Is it the ultimate solution? Can you stop all surges and prevent all
possible saftey hazzards? No. But you can increase your chances to device
failure by 1000x(I'm just making that number up but seems resonable) by
adding even a cheap surge protector(a simple mov). Of course even that
introduces some saftey issues as you have proven by your links... MOV's are
perfect and if they short out then you can have a serious saftey problem.

Anyways...


.

Relevant Pages

  • Re: Band Uisng Tripplite Line Conditioners/surge-suppressor
    ... But put a 100 amp surge on that same Romex wire. ... approaching 12,000 volts, it is not earth ground. ... Therefore voltage increases to dissipate more energy ... Cable TV needs no surge protector. ...
    (alt.guitar.amps)
  • Re: surge protectors
    ... cable may be an incoming source of electricity called a surge. ... earth ground used by AC electric and telephone. ... No protector is required to earth coax cable surges. ...
    (alt.home.repair)
  • Re: Long cat5 run question
    ... seek earth ground. ... where is surge ... Times article describes what an effective MOS device does. ... Adjacent plug-in protector performed as an MOS ...
    (alt.internet.wireless)
  • Re: Modem problem
    ... Appreciate why lightning may have found a path to earth via your ... The telephone line already has a superior protector ... a better earth ground. ... So how was a modem damaged - internal or external? ...
    (microsoft.public.windowsxp.hardware)
  • Re: Surge protectors to use with home electronics when grounding is not available?
    ... not in earth, then were does surge energy get dissipated? ... in the device which is absorbing the surge. ... a plug-in protector works by clamping to nothing. ... neutral and earth ground also, if earth ground is present in the house ...
    (sci.electronics.basics)