Re: "chain" surge suppressers?

On Jul 18, 2:59 pm, Douglas Johnson <p...@xxxxxxxxxxxxx> wrote:
Please list the exact specifications you desire and an example of a protection
claim that would satisfy you.

Cited are what is required by numerous industry standards,
publications and professional experience. For example, two 'top of
the front page' articles in Electrical Engineering Times entitled
"Protecting Electrical Devices from Lightning Transients" define what
provides protection. Required is a low impedance connection to earth -
to shunt and dissipate surge energy harmlessly:
http://www.planetanalog.com/showArticle.jhtml?articleID=201807830
The inductance of a wire is predominately related to its
length and weakly related to its diameter.

Why do plug-in protectors have all but no earth connection? Wire
impedance. Whereas a plug-in protector may be connected less than 0.2
ohm resistance to earth; it may be 120 ohms impedance. Even a trivial
100 amp surge would put something less than 12,000 volts between
protector and breaker box. AC electricity about wire resistance.
Surges are about wire impedance - which is why EE Times discusses
impedance - not resistance. An AC wall receptacle is only a safety
(or equipment) ground; not earth ground. It has low resistance and
excessively high impedance.

Why do industry professionals discuss wire impedance whereas plug-in
promoters do not? Well known for generations, every foot of wire
increases wire impedance adversely. Even sharp wire bends increase
wire impedance; compromise the earthing. How many sharp wire bends
from a wall receptacle safety ground to breaker box? 50? Wall
receptacle provides safety ground; not earth ground. An effective
protector requires that short connection to earth. Even wire splices
can unacceptably increase wire impedance - but not resistance.

User error. User has installed a protector that is too far from
earth ground (therefore all but no earthing) and too close to
appliances. Plug-in protectors without a properly earthed 'whole
house' protector means a protector may even earth surges 8000 volts
destructively through adjacent appliances. How do we eliminate this
failure? Properly earth one 'whole house' protector. Surge energy
must be kept out of the building.

Also necessary is the single point earth ground - what every
incoming utility wire in every cable must connect to:
Lightning is essentially a current impulse which is trying to return to earth.

Why was lightning striking Ben Franklin's church steeples? Even wood
and other household materials are electrical conductors. Just more
reasons why protection inside the building is complicated and
compromised; why surges must be earthed outside the building.

Practical application of the connection and electrode.

Low impedance demands a ground wire typically 'less than 10 feet
from each utility wire (in every cable) to earth ground. Some of my
best experiences involved a less than three foot connection to earth.
Sharp wire bends, passing through metallic sheets or conduits, and
splices will also compromise protection. So that wire does not induce
surges on other wires, grounding wire is routed separated from other
non-grounding wires (just another reason why Romex ground wire does
not provide effective earthing). All is accomplished (often trivial)
at the service entrance with proper planning.

How good must an earthing electrode be? Locations with average
lightning storms and conductive earth can be earthed by a 10 foot
ground rod. Others who want an even batter protector expands that
earthing electrode. Better conductivity and equipotential means
better protection. To you, that means installing a best single point
ground. Best solution in low conductive (ie sandy) soil for a high
lightning area is why massive earthing electrodes are installed - ie
Ufer or halo (perimeter) grounds. Better earthing means a more
effective protector:
http://members.aol.com/gfretwell/ufer.jpg
http://scott-inc.com/html/ufer.htm
http://www.psihq.com/iread/ufergrnd.htm

What most determines protector effectiveness? Its earthing. When
surge damage results, ask where earthing is inferior or compromised;
as discussed on 14 Jul 2008 at:
http://tinyurl.com/6bc2jw

.

Relevant Pages

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