We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in GFCI
outlets in bathrooms, kitchen, garage, outdoor locations. So from a
people safety perspective I think that's about as good as we can do,
and grounding would not improve that situation.
Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
<5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
There is also a product sold by Tytewadd, which clamps at 130V, maximum
current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.
Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
Whole-house surge suppression is a good idea and that is based on personal
130 volt clamp is too low. 70 joules is too low.
There was no Internet when I installed my first unit and I went to the best
electrical supply house in my vicinity and talked to those folks. Now, you
can Google this to death.
I think I can safely say I've googled it to death already. I couldn't
find any information on the Tytewadd device except from the
manufacturer. Why is a low voltage clamp bad? I'd think that it would
be better to clamp as low as possible.
I asked a local electrician about installing a whole house surge
suppressor and he said he hadn't heard of them, and I can't find a
local supplier that stocks them. I guess that's because we're in a low
lightning risk area (we're lucky if we get one or two thunderstorms per
year), but it still seems like cheap insurance. On the other hand, if
these units are not effective for protecting electronic equipment, then
I'm back to square one.
Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the line
between neutral and hot which are most likely to cause damage to the
Without a ground that can't do anything about common mode surges where
the same surge voltage is present on both the hot and neutral however
these surges are less likely to damage the connected device unless it
has a ground connection like a CATV connection.
Hmmm. Some surge suppressor power strip vendors specifically say that
they offer no protection and no warranty when used in an ungrounded
outlet. Are you saying that they can shunt current between hot and
neutral in a differential surge? I thought that all surges were
shunted to ground?
A typical cheap suppresser has three MOVs, one hot to ground, one
neutral to ground and one hot to neutral. Obviously the hot to neutral
MOV can clamp transients that are differential across the hot and
neutral regardless of the presence of a ground connection. Suppressers
using gas discharge tubes would be similar.
If the surge is common mode, raising the voltage on both hot and neutral
and the device connected has no ground connection anywhere like a CATV
connection, then the entire device will jump to the higher potential
which should cause no damage. The hot-neutral suppresser would still
attempt to clamp any excess imbalance so the device should not see any
effective over voltage unless the surge exceeds the suppressers clamping
As for warranty, certainly the suppresser can't work to it's full design
capacity without a ground so they don't want to warranty anything. That
doesn't mean that the suppresser will be useless without a ground.
Common mode surges are a most typical source of electronics damage.
Point of use (plug-in) protector would do what already exists inside
appliances. Appliance protection is typically so superior that a
surge, incapable of damaging that appliance, can still cause a plug-in
protector to smoke. This undersized (smoking) protector gets the naive
to promote more sales of a so profitable and ineffective product.
Take a $3 power strip. Add some $0.10 parts. Sell it for $20 or
$120 as a plug-in protector. Do anything possible to avoid discussing
THE most critical component in every protection 'system': earth ground.
Amazing how word association (surge protector = surge protection)
replaces science to promote myths.
Appreciate further problems with plug-in protectors even 20+ years
after UL1449 was created (because this happened so often). Would you
put these on a rug or on a desk full of papers?
Earthing is the most essential component in every protector system.
Industry professionals, your telco, AC electric companies, commercial
radio and TV broadcasters, ham radio operators, and even Ben Franklin
demonstrated this all so necessary 'system' component. Do they install
plug-in protectors? Of course not. No earth ground means no effective
protection. True 70 years ago. Now essential for homes due to
something new - the transistor.
Yes, lack of grounding will not defeat point of use suppressers
because those grossly overpriced protectors don't even claim to protect
from a typically destructive transient. But then don't take my word
for it. Where does it list each type of transient with numbers to
define protection? It does not. They hope you will 'assume' it is a
complete protection solution. Assuming is what recommends plug-in
protectors - myths based only on assumptions that even the manufacturer
does not dare to claim.
How to quickly identify an ineffective protector: 1) No dedicated
earthing wire. 2) Manufacturer avoids all discussion about earthing.
Effective protection earths before transients enter the building - so
that transients do not overwhelm protection already inside appliances.
Transients that don't enter a building therefore do not find
destructive earthing paths everywhere inside that building.
Effective protectors are also sold under names of responsible
manufacturers such as Square D, Cutler-Hammer, Siemens, Intermatic,
Leviton, and GE. Effective protector solutions will not be found in
Radio Shack, Sears, Staples, Best Buy, K-mart, Office Max, Bed Bath &
Beyond, Wal-mart, or the grocery store. How do you know? Where is
that all so necessary earthing wire?
Solutions are sold in Lowes, Home Depot, and most any electrical
supply house. They have been necessary since the 1970s - when
transistors began appearing in homes. Home earthing system must both
meet and exceed post 1990 National Electrical Code requirements.
Above is installed for secondary protection. Primary protection
'system' should be inspected:
A 'whole house' protector is protection for about $1 per appliance.
Superior solution - and it even costs less money. A protector is only
as effective as its earth ground.
Pete C. wrote:
[lotsa good stuff re:grounding snipped]
'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't mean
that their service is *ungrounded*, only that there's not a separate
ground and neutral, correct? So their electrical service *is* grounded
(should be, anyhow).
Just as McDonald\'s is where you go when you\'re hungry but don\'t really
care about the quality of your food, Wikipedia is where you go when
A house using two wire receptacles would be wired for pre-1990
earthing requirements. One need not ground wall receptacles to have
superior surge protection. But earthing at the AC mains box must be
upgraded to post 1990 code AND meet additional requirements defined in
the previous post.
This proper earthing and a 'whole house' protector are less
expensive, far more effective, AND enhances household human safety.
All this without massive rewiring of a house for three wire
receptacles. Notice a critically important parameter for surge
protection. That earthing must be short (ie 'less than 10 feet').
What is necessary to install an effective 'whole house' protector?
That household earthing must be upgraded to meet and to exceed post
1990 NEC code requirements. Superior protection regardless of two wire
or three wire receptacles.
Meanwhile, too many homes do not even have earthing that meets those
1960 earthing requirements. Too many see lights working - then assume
everything is just fine. One home even exploded because that missing
earthing (and other factors) caused electricity to conduct through the
Not only is 1960 earthing typically not sufficient for transistor
protection. Too often, earthing is compromised as to not provide human
protection. That earthing must both meet and 'exceed' post 1990 code
requirements. To better appreciate why, learn about 'wire impedance'.
Not resistance - impedance.
David Nebenzahl wrote:
<useless bogus blather deleted>
There you go again with your nonsense.
Care to explain how a common mode surge can damage a device that has no
A device with only two electrical connections, hot and neutral, does not
care in the least what the voltage on these lines is relative to ground.
0 Volts and 120 Volts or 12,000 Volts and 12,120V look *exactly* the
same to the device. Unless the surge is high enough to blow through the
insulation of the devices enclosure and arc to ground it is absolutely
irrelevant to the health of the device.
The same way a person that has no ground connection can plug his finger
into the hot and not the neutral or ground contact in a socket and still
get electrocuted. When you say the device has no ground connection, what
you really mean is that it has no *obvious* ground connection.
And even if your device is a hundred million ohms from ground, it may be
insulated from ground by something that will punch through when a 5,000
volt common-mode surge hits the device.
Asking Iran and Syria to help us succeed in Iraq is like your local fire
department asking a couple of arsonists to help put out the fire.
I already covered that in another reply. A device with no ground will be
unaffected by a common mode surge up to the point of insulation
breakdown through for example, the plastic case of the device, the wood
table it's on, the carpeting under the table, etc. Basically a very
close lightning strike which no affordable protection device will be
able to protect against.
Static electric charges can build across shoes. Touch something such
as a door or electronics. How does a circuit conduct electricity from
finger to charges beneath those shoes? Many parts in that circuit are
not conductive? But at those higher voltages, things not considered
conduct become conductive.
Yes, an appliance without a better connection to earth will be less
susceptible to damage. This is why some things are damaged whereas
others are not. Even wall paint may become a conductor at these
voltages. It is not possible to isolate an appliance from destructive
transients. Otherwise lightning could not conduct through the best
insulator - 3 miles of air.
Why does lightning strike a wooden church steeple? Wood is not a
conductor? That is your reasoning. But wood is both a conductor and a
connection to earth. Concrete is not a conductor according to your
reasoning. But concrete is such a good conductor as to be recommended
- Ufer ground.
Protection has always been about earthing transients so that
destructive paths are not found through appliances or through wooden
You are assuming things not conductive when a building is chock full
of conductive paths to earth. Just another reason why every high
reliability building earths before transients enter a building. They
know better. A transient permitted to electronics can find surprise
paths to earth. Best protection which is also less expensive and easy
to implement has always been to earth before a transient can enter a
building. One properly earthed 'whole house' protector is that
We are not protecting from close lightning strikes. Protection
already inside appliances makes that irrelevant. We are protecting
against a direct strike to AC mains down the strike which is a direct
strike to every household appliance. Only some appliances
destructively earth that direct strike. Which ones? You do not know.
But that answer is irrelevant if the direct strike is earthed before it
enters a building. Some utilities are earthed directly (cable TV and
satellite dish). Others require a 'whole house' protector (AC electric
and telephone). But that protection will only be as good as a single
point earth ground.
Again, this was both a problem and solution well understood way back
in the early 1900s. The technology so effective that your telco
installed it on every phone line. Why would a telephone operator in a
wooden room become a path to earth via non-conductive headphones and a
wooden chair? Those become conductive paths to earth through her body.
Why did that telephone operator not remove her headset when
thunderstorms approached? Even long before WWII, single point earthing
was well proven protection. The need for earthing has been that well
understood for that long. Otherwise lightning could find a path to
earth through that operator. If Pete C's reasoning was correct, the
operator was never at risk. Telcos knew better. Even those
non-conductive headphone and wooden chair could become a conductive and
harmful path to earth.
Protection is about earthing before transients can enter a building.
One 'whole house' protector is defined by the quality of its earthing.
Pete C. wrote:
Woof, talk about making it up as you go! You've neglected to consider any
of the actual elements that appear to cause wood to conduct, etc.. You've
completely ignored the real components of impedance in the presence of
humidity, chemicals, and any material you mentioned. You look pretty bad
with statements such as these becuase as stated they are incorrect.
A common mode surge comes in along the 2 wire power cord to line lump
powering a laptop computer sitting on a wooden table. The laptop has no
connections to any other device i.e. WiFi network. Unless the surge is
of a large enough magnitutde to punch through the insulation of the
devices in question there should be no damage.
temporarily into conductive material) is what surges do. Again,
appliances already contain any protection that will work on their power
cord. But a destructive surge creates conductive paths through items
(such as the wooden tabletop or church steeple) normally not considered
Another classic example is a dialup modem. How are they damaged? A
most typical path goes into computer on AC mains, through modem via its
off-hook relay, then out to earth ground via telephone line. How does
it make a conductive path to a galvanically isolated phone line? Surge
creates a conductive path from relay's coil, across an isolation
barrier, to relay's wiper. IOW destructive surges are destructive
because they create conductive paths through non-conductive material.
So what is a building owner to do? The building is chock full of
potentially conductive paths to earth ... which is why protection must
earth before transients can enter that building.
A computer connected only to AC mains and using WiFi is less likely
to be damaged - just like the TV adjacent to a VCR might not be damaged
when VCR is destroyed.
Not only is earthing essential - so that protection inside that
laptop is not damaged. The protection is layered. A 'whole house'
protector earthed by a building electrode is secondary protection.
Primary protection must also be inspected:
Surge protection is not installed for every transient. Protection
inside all appliances makes most all transients irrelevant - whether
laptop uses WiFi or phone line. But a destructive transient that would
otherwise punch through such protection is why effective protectors are
installed. Such surges occur typically once every seven years - a
number that can vary significantly even within a same town. We earth a
'whole house' protector so that the destructive surge does not punch
through insulation - protection that exists in all electronics.
Anything that a 'plug-in' protector would accomplish is already
inside electronics. Protection that can be overwhelmed by punching
through insulation. Just another reason why money spent on a plug-in
protector is better spent to enhance earthing for a 'whole house'
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