Re: Surge protectors to use with home electronics when grounding is not available?

On Jun 28, 8:17 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@xxxxxxxxxxx> wrote:
I work in an industrial environment where we get hit on an average of
3 times each year from storms. It destroys a lot of stuff how ever,
there is very little in real life events where we work that supports
your theory as you have so edited.

We have equipment all over that uses MOV's or devices like it that
does not depend on ground as part of the device protection. The ground
is simply there connected to the chassis and cabinets to protect the
user/operator. If it happens to be on a GFCI. It could trip the circuit
but in that case, the device attached still gets whacked normally.

You use unearthed MOVs everywhere. You suffer damage from lightning
3 times a year. You call that protection? More likely, MOVs without
earth ground are earthing surges destructively through equipment.
Effective protection means direct strikes (25 annually atop the Empire
State Building) and no damage.

If MOVs are properly installed (with the required short connection
to single point earth ground), then damage occurs zero times every
year. Damage three times a year is unacceptably excessive. Your
industrial environment "does not depend on ground as part of the
device protection." Therefore damage is acceptable? Average
locations may suffer a serious surge once every seven years without
damage, if protectors are properly earthed.

Jamie demonstrates why the US Air Force demands:
15.1. Entering or exiting metallic power, intrusion detection,
communication antenna, and instrumentation lines must have
surge protection sized for lightning surges to reduce transient
voltages to a harmless level. Install the surge protection as
soon as practical where the conductor enters the interior of
the facility. Devices commonly used for this include metal
oxide varistors, gas tube arresters, and transzorbs.

Lightning damage three times a year is so unacceptable as to be
traceable to human failure. Properly installed 'whole house'
protector with a 'less than 10 foot' connection to earth is why:
http://www.tschmidt.com/writings/HomeLAN2008.htm
6.10 Secondary Lightning Protection
The key to minimizing lightning damage is bonding all services
together with a low impedance path to earth ground. All
conductors entering the building must be bonded together
and equipped with lightning protection. This minimizes
difference in potential during transient conditions.

6.10.1 Electrical
Whole house surge protector should be used to protect the
electrical system. Remember goal is to direct excessive energy
into a low impedance ground and to provide low impedance
bonding of all metallic conductors. ...
Lightning protectors do not absorb energy they divert it. If the
diversion path is not low impedance a substantial voltage
difference is created. This is what kills electronic gear.

Routine is a building connected to overhead wires all over town to
suffer maybe 100 surges during every storm and no damage. A protector
is only as effective as its earth ground. Jamie's protectors are not
earthed. Therefore surge damage is acceptable?
.

Relevant Pages

  • Re: Lightning and Switches
    ... From your description, surge electricity flowed ... Possible that four ports in the Cisco share a common interface ... 10 would damage ports 9 through 12. ... overwhelms protection already inside ethernet interfaces. ...
    (comp.dcom.sys.cisco)
  • Re: Soon to arrive my HDTV
    ... Why re-engineeer protection that is already inside every TV? ... a surge that seeks earth ground. ... That surge enters a TV to find earth ground outgoing via some ... destructive surge is on one or both AC wires and seeking earth ground. ...
    (alt.tv.tech.hdtv)
  • Re: Soon to arrive my HDTV
    ... Why re-engineeer protection that is already inside every TV? ... a surge that seeks earth ground. ... That surge enters a TV to find earth ground outgoing via some ... destructive surge is on one or both AC wires and seeking earth ground. ...
    (alt.tv.tech.hdtv)
  • Re: Fiber-optic isolator?
    ... If every wire is earthed where entering the ... A first building may act as a lightning rod to find earth ground, ... any protector destroyed by a surge was not providing ... standard protection system means a direct lightning strike and ...
    (alt.internet.wireless)
  • Re: Phone Line Interfacing - FCC Part-68
    ... protection is, a direct strike can kill it. ... lightning strike is not truly "ground", ... For surge protection, ... that earthing wire is less than 10 feet AND is the same earth ground ...
    (sci.electronics.design)
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