Thanks for all replies,
Surge protection is the same concept. Lightning seeks earth
ground via utility wires. If not earthed before entering a
building, then lightning seeks earth ground, destructively,
Note the concept. Destructive surges are electricity
meaning that there must be both an incoming path and an
outgoing path to earth. First a complete electric circuit
forms from cloud to earth. Then something fails as surge
current in that circuit increases.
Appliances already have effective internal protection.
Appliances can typically withstand on the order of 1000
volts. But that internal protection will fail if
overwhelmed. Protection is effective only if a surge is
earthed before it can enter the building. Earthing is the
surge protection. A surge protector is only effective if
surge is earthed by that protector before surge can enter the
building. Protector beings only as effective as its earth
Such 'whole house' protectors have been so proven effective
as to be standard even before WWII. Todays 'whole house'
protectors are even more robust and less expensive. But like
in the 1930s, that connection to central earth ground (either
through a surge protector or via direct hardwire) must be less
than 10 feet. That distance is one of many critical
For example, CATV and satellite dish don't need a surge
protector since utility wire must connect to central earth
ground by hardwire (before entering the building). AC
electric and telephone cannot be earthed directly. Therefore
those utilities require 'whole house' protectors. 'Whole
house' protectors being so effective that the telco installs
them, for free, both on your building and to protect their
switching computers that must never suffer damage.
Wires highest on poles, most exposed, most often stuck, and
that enter a building without a well earthed surge protector
is the AC electric wire. Effective 'whole house' protectors
for residential AC electric cost about $1 per protected
appliance. Compare that to an excessive $20 or $50 for a
plug-in protector that does not even claim to protect from
destructive surges AND that has no dedicated connection to
Plug-in UPS is no more effective. It connects computer
directly to AC mains when not in battery backup mode. Its
surge protector circuit is same as found in power strip surge
protectors. Building wide UPS systems do provide surge
protection since they are earthed at the UPS. But plug-in
UPSes have the same problem found in power strip surge
protectors: no earth ground means no effective surge
protection. So just like a power strip surge protector, the
plug-in UPS also quietly claims no such protection abilities.
Available retail from Home Depot are Intermatic EG240RC or
Siemens QSA2020. Other 'whole house' protectors are from
Square D, Cutler Hammer, Leviton, and a long list of other
products. Surge protectors are but one component of a surge
protection system. They don't stop, block, or absorb surges -
as urban myth promoters would claim. Protectors are only
effective when making the connection to earth ground. Central
earth ground is THE most critical component on an effective
surge protection 'system'. A surge protector is only as
effective as its earth ground - which serious surge protectors
will mention because earthing is that essential.
One aspect of this is that you are more likely to know when your surge
protection has failed than when it has succeeded.
> Destructive surges seek earth ground. Franklin solved the
> problem of damaged churches by intercepting and earthing
> electricity before it could strike a steeple. The Franklin
> air terminal 'system' was made effective by its most critical
> component - earth ground.
This is certainly interesting reading w_tom. So how much would you
expect an electrician to charge to install one of the devices you have
mentioned from Home Depot? And how do you know if your house has a
"effective earth ground"?
Joules is the important parameter here. A surge protector
that fails due to a surge is ineffective AND has left
appliances exposed to surges. But an effective surge
protector that shunts a direct lightning strike to earth
ground is not damaged. Surge happens without homeowner ever
knowing the surge existed - effective protection.
Also standard in both Empire State Building and WTC. 25 and
40 direct strikes per years and yet no one inside even
noticed. Surge protection earths direct strikes and lights
did not even flicker. TV and FM stations continue
uninterrupted. Such is why whole house protectors are so
effective. They are properly sized so as to not be damaged by
direct lightning strikes AND they are properly earthed so that
the direct strike results in no interior surge currents. At
best, the occupant only hears noise on his stereo amplifier.
Surge protection from direct strikes is that effective because
occupants don't even know a surge has occurred.
So how does the occupant know when superior surge protectors
are installed? Occupant can only consult the numbers, wiring
practices, visually inspect earth ground, and learn the
principals to know when effective protection is installed.
Ineffective protection is obvious. Damage - even to surge
protector - defines an ineffective surge protection system.
Effective protectors are that effective.
I run everything through a refurbished SmartUPS APC 700. It
compensates for spikes and snags in the power line. Think I paid ~$100
for it on eBay. Nice to be able to shutdown gracefully especially if
you are doing something like a partition resize operation!
'Whole house' protector sold in Home Depot costs less than
$40. But if an electrician is required, his minimal cost (and
his higher price for same protector from electrical supply
house) will apply. After all, someone must pay to roll that
truck. But then that electrician's cost is required if your
earthing (and safety ground connection to water pipe) need be
"Whole house" protector is easily installed if you can
install a circuit breaker and drive a ten foot rod into
earth. If that is not possible, then an electrician should be
Surge protectors are simple science. The art of protection
is earthing. Is one 8 foot rod (some electricians cheat and
only installed 4 foot rods) sufficient? Factors such as
quality of soil, different geologies on the property, etc all
make effective earthing difficult to judge. In new
construction, the footing for a foundation could make a
perfect and so inexpensive earth ground. Ufer grounding
should be standard in all new homes. But once the building is
constructed, then good earthing becomes expensive and harder
As noted, most will get minimally adequate earthing from an
8 foot copper ground rod. Additional rods, per NEC
requirements, will significantly enhance that earthing.
Every incoming utility must connect to same point on that
central earth ground. For example, a 10 AWG wire from telco
supplied surge protector (NID box) would bond to same rod top
as breaker box electric ground and wire from CATV ground block
(before CATV enters building). How wires are routed is even
critical. No sharp bends. No splices. Not inside metallic
conduits. Short as possible. Separated from (never bundled
with) non-grounding wires. Meet these requirements rather
than be neat. IOW effective earthing goes beyond what is
required by National Electrical Code which is why some
electricians are not fully knowledgeable about earthing also
for radio frequency transients knows as surges. That earth
ground serves multiple masters - human safety and transistors
safety. NEC is only concerned with human safety.
Even in telco central office exchanges, surprises were
discovered when the first electronic switching computers
(ESS-1) were installed. When damage resulted, humans then
returned to analyze and correct a weakness in the earthing
system. Lightning will find weaknesses. Humans do make
mistakes. A single earth ground rod may be sufficient
protection. But if any future damage results, then the
earthing system may need be enhanced. Humans sometimes must
learn from their mistakes. However some humans instead
foolishly try to solve surge problems with magic surge
protector boxes - rather than address the art of protection -
The last figure demonstrates some principals. For example,
each structure has its own central earth ground. Surges can
even enter via buried wires. All wires enter structure at a
common service entrance with connection to central earth
Earth ground is the best earthing at the facility. But for
even better protection, a ground wire encircles the structure
- all earth underneath the structure has equipotential.
Depends on how much work and money you are willing to spend,
how 'dangerous' the geology for surge damage, and how
expensive the household electronics. But for most households
with good soil and lots of expensive appliances, less than 10
foot connections to a central earth ground make from the
single 8 to 10 foot ground rod is absolutely necessary - no
way around that minimally necessary requirement.
Benchmark in surge protection is Polyphaser. Their
application notes are considered legendary. An example:
When a group of starlings (birds) cause the local powerline
to short - a huge power surge occur in my neighborhood.
My neighbors reported losing stereos, TVs, microswaves, and
other stuff. Over half of my surge protectors were destroyed.
Lost 2 tripp lites, 2 kensingtons, 1 belkin, 2 no-name surge
protectors. Lost a tripp lite UPS in that electrical surge too.
All surge protectors that were not connected survived the power
surge. The tripp lites had successfully protected the fax/answering
machine (which is always on ). The safest thing to do is to
disconnect everything - unless you really need to draw
Lee Parsons wrote:
> When I was in Army Radio School wayyyy back when, we were taught that
> a single rod was minimal and was used for our mobile radio and
> radioteletype systems, but a much better system for fixed
> installations was a "star ground" which involved five rods (four in a
> square and one in the center connected to all).
I read hundreds of dollars in destroyed surge protectors
whereas one 'less than $50', 'whole house' protector could
have accomplished same AND provided protection from the
destructive common mode surge as well.