The best information on surges and surge protection I have seen is at:
- "How to protect your house and its contents from lightning: IEEE guide
for surge protection of equipment connected to AC power and
communication circuits" published by the IEEE in 2005 (the IEEE is the
dominant organization of electrical and electronic engineers in the US).
- "NIST recommended practice guide: Surges Happen!: how to protect the
appliances in your home" published by the US National Institute of
Standards and Technology in 2001
The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.
More important than just connecting to the same electrode, the entry
protectors for phone, cable, ... must connect with a *short* wire to the
‘ground’ at the power service. With a large surge, the house ‘ground’
will always rise above `absolute' ground. You want the power and cable
and phone 'grounds' to rise together. The consequences of not having a
*short* connection are illustrated in the IEEE guide starting pdf page
40. The guide says that lacking a short interconnection "the only
effective way of protecting the equipment is to use a multiport protector."
With your signal entry protectors in the basement, you can’t get *short*
connections to the ‘ground’ at the power service. (But you could run a
phone wire from the phone entry protector to the area of the power
service, install a 2nd protector, and distribute wiring from there. Same
According to NIST guide, US insurance information indicates equipment
most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
All can be damaged by high voltages between power and signal wires.
Complete nonsense. The NEC has *required* the water pipe (10 ft or more
buried metal) to be used as a grounding electrode since 1493.
The illustrations do not particularly improve problems of having signal
entry distant from the power service.
As others have said, adding ground rods is probably easier than finding
where your system is earthed. And the added rods can be near the power
The house is 35 years old and never had any problems with anything
other than computer equipment.
This has caused another question I have had in the back of my mind. We
have had CATV for at least 15 years and have never had any damage to
Of course we don't leave the TVs on 24/7 like we do the computers.
True or False? Having the TV off (not unplugged) lowers the risk of
lightning entering through the CATV? I would say false. I am
You may never have any damage to anything. Surges are chance events.
Most TVs these days are never actually off. If you have a remote
control, part of the TV is always on. And only one of the power wires is
switched if a TV is actually turned off. That might eliminate surges
entering on the power line, but not surges from power wire to cable
wire. And, as indicated in the IEEE guide, surges can enter with a
voltage between the cable center conductor and shield.
A UPS of the kind likely used in a house does not intrinsically provide
any surge protection. The 'protected' load connects directly to the line
except during power loss. The same protection that is included in a
plug-in suppressor may (or may not) be included in a UPS. Ratings range
from junk to very high. UPSs typically do not have very high ratings.
Any surge suppressor in the US should be listed under UL1449.
Having 2 ground rods does not mean the rods will be at the same
potential if there is a surge. Even if you have a good earth
'connection', the potential at different locations can be different.
If you had a modest surge of 1000A earthed through a ground rod with a
very good resistance of 10 ohms, there would be a voltage of 10,000V
from the rod to 'absolute' earth. As a rule of thumb 70% of the voltage
drop from the rod is in the first 3 feet. From the rod to the earth 3
feet from the rod will be 7000V. From whatever is connected to the rod
to the earth 3 feet from the rod can be a lot higher with a long wire
making the connection.
I don't question the ground system of the house. I suspect the water
pipe under the house. We have never had any problems with electrical
equipment in 35 years. Only computer equipment. It is not the power
supplies on the computer equipment. It came in through the CATV and
hit the modem, router, and 2 motherboards.
After a lightning hit on my computer equipment, I started looking at
the way my CATV and phone were bonded to my copper pipe under the
house. I have a UPS now.
I can't locate a place where the water pipe is grounded. I don't
think it even comes in contact with the ground except maybe where it
enters the laundry.
The wall I am going to fish will be almost directly above the water
pipe in the basement. The number 6 will have one bend going down the
wall. I will then clamp one end to the water pipe in the crawlspace
and split bolt the other to the exposed number 6 in the attic. The
number 6 will have one bend to attach it to the split bolt.
I will be driving a ground rod at the place where I clamp the panel to
the water pipe. I will make sweeping bends, but I don't see why the
bond wire can not have tight bends. There will be a direct grounding
electrode at both places.
Suspect your grounding system. You are suffering electronics
damage. Therefore a surge is finding earth ground, destructively, via
appliances rather than being earthed before entering the building.
Either a surge will be earthed on a short connection OR it may find
destructive paths to earth via appliances.
The water pipe is buried. However you must remove any electricity
from that pipe that might, inadvertently or accidentally, get
conducted into those pipes. That is electricity either entering via
buried side of pipe OR from inside the building. Bonding makes any
voltage on pipes same as on all household wires. No voltage
difference? Then no dangerous electrical currents. That 'bonding' is
a wire from cold water pipe to breaker box. Bonding is that wire's
purpose; to remove electricity from pipes for human safety reasons.
That bonding wire must be located to 'pick up' water pipe currents
from inside the building and from outside the building.
Some jurisdictions take it one step farther: now require a 6 AWG
wire bonded to a steel bathtub. Again, bonding is for human safety;
has no relationship to electronics protection.
View your TV cable. When cable companies were purchased with intent
to provide reliable service (including phone and internet), then cable
guys were completely retrained in earthing. That cable cannot enter a
house directly. First that cable must connect short to the single
point earth ground - the grounding that you must suspect - the earth
ground rods you will be installing. Entire surge protection for cable
is a ground block and a 'less than 10 foot' wire to earth ground. No
protector is encouraged by a cable company. Wire is completely surge
protected without a protector. Wire length is critical. Electricity
is not same at both ends of a wire.
Note the repeated references to wire length. Shorter wire length to
earth ground is critical to electronics protection. That cable cannot
even be connected to a water pipe. Water pipes are no longer
sufficient for earthing. Cable must connect directly to the same
dedicated earth ground used by telephone and AC electric. Cable's
ground wire also must have no sharp bends, short as possible, not
bundled with any other non-grounding wire, etc.
Where is the cable earthed? How long is that earthing connection?
Breaker box must be 'bonded' to water pipe AND connected to another
ground - earthing electrode. Those are separate grounds. Wire length
to water pipe is not critical. Wire length, and no sharp bends, no
splices, not inside metallic conduit, etc is critical to earthing.
Earthing wire has nothing to do with water pipe 'bonding'. That
earthing wire must be one solid wire from breaker box safety ground
(bus bar) to earthing electrode; '10 feet or shorter', no splices,
separated from other non-grounding wires, etc.
Again, appreciate that water pipe bonding for human safety does not
serve the many other functions provided by a different ground: earth
ground rods. 'Bond' to water pipes to remove undesirable (dangerous)
electricity. Cable TV wire cannot be bonded to outside water faucet.
That would make the earth ground connection too long. That would
'dump' electricity into water pipes - unacceptable. Only wire
connection to water pipes is 'bonding' to remove electricity from
those pipes - essential for human safety.
An older home may have bonded things to water pipes. Once that
connection was legal. Bonding (to safety ground something - to dump
electricity into pipes) is no longer legal and is dangerous. Earth
electrodes may dump electricity into earth. Two different ground
wires from same breaker box perform different functions. A connection
from breaker box to earth must be 'less than 10 feet', no sharp bends,
not inside metallic conduit, etc.
What is this exposed 6 AWG wire in the attic? What does it connect
to and what is its purpose?
Drive earth ground rods as close as possible to where AC electric
box, telephone NID, and cable TV are located. Each utility must have a
separate and dedicated ground wire that meets all other ground wires
at that earthing electrode - a single point earth ground. That earth
ground performs functions not intended for a water pipe ground.
w_ is a nutcase on this issue. The NEC has *required* water pipes (10 ft
or more buried) to be used as a grounding electrode since 1494 (is that
“Remove electricity from those pipes” is technical illiteracy.
Continued nonsense. When a water pipe is used as a grounding electrode,
phone and cable protector ground wires (among other things) can be
connected to it in the first 5 feet inside the building. (This is not
likely to result in a good “single point ground”.)
The most important feature of a “single point ground is a *short* ground
wire from phone, cable, ... entry protectors to the service panel
ground. (The service panel ground is the magic point because the neutral
and ‘ground’ are tied together at that point - it is the ground
reference point of the power service.) If the wire is not short, high
voltages can develop between power and phone, cable, .... When the
‘ground’ rises from ‘absolute ground’ with large surge current, you want
the power and phone and cable ‘grounds’ to rise together.
Francois Martzloff, who was the NIST guru on surges and wrote the NIST
guide, has written "the impedance of the grounding system to `true
earth' is far less important than the integrity of the bonding of the
various parts of the grounding system."
The way I read Terry’s description, the phone and cable protectors are
at significant distance from the power service, as is the case in many
houses. In that situation, the IEEE guide says "the only effective way
of protecting the equipment is to use a multiport protector."
On Sep 11, 1:36 am, firstname.lastname@example.org wrote:
Lightning seeks earth ground. If conducted to earth via wrong
paths, then you have damage. Which incoming paths are you trying to
protect? 1) Lightning strike to your chimney? 2) Lightning strike to
utility wires out on the street - a direct strike to household
appliances? 3) Lightning that enters from earth ground on one side
of the house, passes through household appliances destructively, then
continues out other side of house back to earth?
Earthing for first above problem is called Franklin lightning rods.
A rod properly installed above that chimney would connect lightning to
earth without damage. Earthing provides chimney protection. Same
protection for an antenna. That antenna must have its own dedicated
connection to earth, or an earthed lightning rod protruding above that
antenna. How effective is that protection? Quality of the earthing
AND how that earthing connection is made determines whether lightning
will earth via the lightning rod or will find a better earthing
connectcion via something else.
A lightning strike to utility wires (second problem) means each wire
entering a building must be earthed where wire enters the building.
For example, one of three AC wires must be earthed directly to meet
code - for human safety. Inspect that earthing. A bare copper 6 AWG
wire must connect from breaker box to an earthing electrode that is
best 'less than 10 feet' away. No sharp bends. Ground wire routed
separated from other wires. No splices. Not inside metallic
conduit. And not over the top of the foundation and down to an
earthing electrode. That wire must be shorter and with less bends:
directly through foundation and down to that earthing electrode.
Only some requirements are required by code for human safety -
understood by all electricians. Some requirements for lightning
protection must exceed code requirements - such as no sharp bends,
separated from other wires, and 'less than 10 feet'. IOW that ground
wire must meet code for human safety, and must exceed code to earth
lightning (transistor safety)
To avoid the third problem, all incoming utilities must be earthed
to same earthing electrode. IOW all utilities must enter the building
at a same location. If your utilities are widely separated, then one
solution uses a buried wire encircling the building so that all
utilities connect to a common ground system:
Even better is when that earthing electrode completely encircles the
building or if an earthing electrode was installed when footings are
poured (Ufer ground). Why do we install superior grounds? Because
earthing defines quality of surge protection; a surge protector is
only as effective as its earthing.
Solutions provided for three different lightning paths. Only
component always required for surge protection is earth ground. Are
both wires for telephone or the other two AC electric wires earthed?
Ground those wires directly and get no electric or phone service.
Earthing is provided by a 'whole house' protector. During a surge,
those ungrounded phone wires are connected directly to earth by the
protector. A surge dumped into earth via a 'whole house' protector
will not wander inside the house seeking destructive paths through
Another with an agenda will say anything to avoid that fact. But his
own citation says exactly what a protector does. On page 17 (of 24)
On page 6 (Adobe page 8 of 24):
The 'whole house' protector (when properly earthed) is so effective
as to be used in all high reliability facilities. Responsible
solutions don't waste money on ineffective solutions such as 'miracle'
plug-in devices. That dedicated earthing wire is essential. Telco
even installs an effective (earthed) protector on your telephone line,
for free. Find the NID box (where their wires meet yours). Inside is
a 'whole house' protector. But the protector is only as effective as
its earth ground. Is a ground wire from the NID 'less than 10 feet'
to the same earth ground used by cable and AC electric?
A protector does not stop or absorb lightning as some will claim.
Surge energy must be shunted / diverted / connected / bonded / clamped
to earth. Earth is where the energy is dissipated harmlessly. A
protector is simply a connecting device to protection. Protection is
the single point earth ground.
How do you verify your protection system? Follow those bare copper
ground wires from breaker box to find the earthing electrode. Follow
the TV cable before it enters to find a 'less than 10 feet' from cable
to earth ground. Follow a green or gray wire from telco NID to that
earthing electrode. This single point earth ground is a 'secondary'
Also inspect your 'primary' protection system:
Utilities must install earthing especially at AC electric
transformer. Just another earth ground essential to household
Other grounding for human safety was described by volts500 in
"Grounding Rod Info" on 12 July 2003 at:
Not just the same electrode. The phone, cable, ... entrance protectors
must connect with a *short* wire to the ground at the power service.
Widely separated utility entrances can produce a high voltage between
signal and power wires that can damage equipment connected to both. The
IEEE guide provides an example starting pdf page 40. I see no reason to
believe the schemes in w_’s link would significantly help. The IEEE
guide says that if the utility entry points are distant "the only
effective way of protecting the equipment is to use a multiport
w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. The IEEE guide explains plug-in
suppressors work by CLAMPING the voltage on all wires (signal and power)
to the common ground at the suppressor. Plug-in suppressors do not work
primarily by earthing (or stopping or absorbing). The guide explains
earthing occurs elsewhere. (Read the guide starting pdf page 40).
My only agenda is accurate information. That is why I posted links to
reputable guides from the IEEE and NIST. Read them for yourself.
What does the NIST guide really say about plug-in suppressors?
They are "the easiest solution".
"Q - Will a surge protector installed at the service entrance be
sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances,
No for two-link appliances [equipment connected to power AND phone or
CATV or....]. Since most homes today have some kind of two-link
appliances, the prudent answer to the question would be NO - but that
does not mean that a surge protector installed at the service entrance
Some of what w_ says is quite good. What he says about plug-in
suppressors is nonsense. For reliable information on surge protection
read the IEEE and/or NIST guides. Both say plug–in suppressors are
Then read w_’s sources that say plug–in suppressors are NOT effective -
oops - he doesn’t have any sources.
Hate to tell you this but strikes nearby come up through your grounding
system to take out a lot of electrically fragile stuff, especially CMOS
(like the above).
Go with a quality whole house surge protector at the breaker box and
also individual protector strips at point of use. Most small protectors
use a solid state device similar to a zener diode that shunts excess
voltages to ground (and vice versa).
Even better would be a UPS sized for your equipment. I use one UPS per
computer (looks like you have more than one). Two brands I have used
are APC and CyberPower. There are probably more brands out there. They
are very cheap insurance. Find them at Office Depot, Circuit City etc.
Most of the UPS units now available on the consumer market are of the
switching type that transfer the load to the battery powered inverter
before the output of the computer's power supply can fall low enough to
cause disk damage or data loss. That is no were near fast enough to
effect most surges and spikes. In order for the UPS itself, rather than
any built in filtering or Transient Voltage Surge Suppressor, to provide
protection from transient power events it has to be of the continuous
duty type were the battery is always in line and the supplied Ac power
is used to recharge the battery. If the battery is always in line it is
one massive sink for sudden voltage fluctuations. You can get the same
TVSS benefits of a switching UPS by using a high quality TVSS protector.
A copper clad ground rod has a rated life of 40 years. Galvanized are less.
You are better off driving a new rod and just run a new wire. In the time
that you spent looking for the old one you could have had a new one
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