A couple of weeks ago, lighting struck a tree near my house, hit the ground,
entered my underground invisible dog fence, ran through the wire to the
outlet in the garage where the control unit is plugged in including a
lighting protector, scorched the outlet and wall underneath, tripped that
circuit breaker, and also fried the cable (cable TV and internet) at the
Fortunately the cable repair was free, but I paid over $240 for the
invisible fence repair. I asked the invisible fence company if a whole
house surge protector would have helped, and they said not in this case,
that the circuit was fried from the outside to the outlet, not from the
So I'm debating whether to invest in a whole house surge protector or not,
and if so, to buy or "lease". I have two circuit panels and received an
electrician's estimate of over $400 installed since I have two panels.
Another company will install a whole house surge protector for free, I just
get $8.50 added to my electric bill each month, about $100 per year. It
would take four years for the first option to be better. I'm not sure I'll
be here much past six years, when my youngest starts college and we want to
So, should I invest in a whole house surge protector? Does it not protect
against lighting? Do I buy the $400 version or "lease" for $8.50 per month?
Inquiring minds want to know.
A whole house protector wouldn't have protected your invisible fence, for
basically the reason the fence people told you - it was fried from the
near-direct lightening hit. I think it would have protected the Cable TV
and other electronic equipment, assuming the surge was coming via the
electric wiring and not a similar issue to the fence - down the cable line.
I don't think the whole house protectors care whether the surge is coming in
via the wire from the meter, or a wire from so circuit such as an outside
pole light, or in your case the one the fence was connected to. The
exception might be things on the same circuit with the fence since they
would be 'up stream' from the panel where the protection would be.
As for the cost, you are probably best getting a couple estimates - just be
sure they are apples-to-apples comparisons. Equipment does very and so will
Whole house protection could be a sales plus if you sell the house, but for
$400 you can buy a lot of plug-strip type protectors for your electronic
equipment, which you can take with you if you move. They also make small
single outlet models that are used for things like microwave ovens, stove,
and other places where you may not need or want a regular plug-strip.
I agree that a whole house surge suppressor is the best solution
though as you pointed out, it would not protect against transients
entering via the invisble fence.
However, couldn't the OP either buy (or if not available jury rig) a
separate surge suppressor going across the wires to the invisible
fence. Basically, you need a couple of MOVS across the two wires to
the fence and to a good ground. That should surve to stop inbound
transients along the dog wiring.
Where do you get a "good ground"? A surge is relatively high frequency
so wire inductance is a major factor. A branch circuit ground wire is
not a "good ground" unless it is very short to the service panel. The
branch circuit ground wire also introduces the surge into the house
wiring downstream from the service entrance of power and phone and
cable, where you can place suppressors. If you add a ground rod for a
"good ground", the potential at the rod can be far different from the
house earthing electrodes (just like the invisible fence was at a far
different potential than the house earthing system).
Best protection would be if the invisible fence unit was adjacent to the
power service with a short ground wire to the power ground bus or house
earthing electrode system. If you added a MOV from the fence wire to the
earthing system you might shunt out the signal from the capacitance of
the MOV (or maybe it would work). Hams have lightning arrestors for
antenna wires entering a building - should work and not kill the signal.
But they wouldn't necessarily protect the fence unit. You would have to
ask the manufacturer how to protect the invisible fence unit.
I was hoping/assuming that you could arrange to have the invisible
fence wire enter the house near the service entrance (and hence near
the ground rods). I know in my house, I like to have all the utility
entrances grouped in one place anyway to minimize the clutter
Then you would have a proper service ground.
Yes you can do that, and you can even double up (parallel) on the MOVs
to make it stronger. Hook it up to a ground and go the extra mile and
drive a 10 foot ground rod where the wires enter the house and also
ground to that.
That electric fence is just a big antenna begging to get zapped again.
A whole-house surge protector is a good idea, irrespective of whether you
A whole-house surge protector costs about $50 (more or less). If your hand
fits a screwdriver, you can install it yourself. Instructions come with the
If, after you buy one, it still doesn't make sense, post here and I or
someone else will be glad to advise you.
If you've never had a problem with line lightning, I wouldn't bother. I
don't believe that the type of surge protectors you are referring to would
do much to protect sensitive electronics anyway. If you want them to protect
things like well pumps and motors, fine, but the typical lightning strike
that causes a surge, won't be stopped quickly enough or completely, to
safeguard sensitive electronics, and won't help at all if your underground
dog wire gets hit again
You're spot on - if the lightning hits your house. If, however, the
lightning strike is merely near your home, a whole-house surge protector
(WHSP) will help.
As for "quickly enough," reputable WHSPs are rated from "instantaneous" to
five nanoseconds. Top-line WHSPs (Leviton, Intermatic, Square-D, etc.), can
handle surges up to 180,000 amps and provide up to $25,000 damage
reimbursement for connected equipment loss.
Some WHSPs come with attachments to protect CATV and telephone lines.
Do oyu have a recommnedation for a WHSP?
Preferably Square-D (I have used their panels & breakers for the past
30 years with good results)
I had an electrical "event" (not lightening related) last November
that ruined a couple TV's, DVD players, AC adpaters, transformers,
garage door openers, etc.
SoCal Edison wound up paying for all of them but it was a hassle to
buy & replace all the stuff......so I would prefer to avoid
My meter is outside along with a main breaker. The service panel is
in a down stairs laundry room.
Where should the WHSP be installed?
Would I bust open the wall near the panel to install another box and
the WHSP would intercept the lines from the main breaker to the
or would the WHSP have to go outside near the meter / service
I;m sure if you check their website you can find what ones they
It can go either outside at the main breaker or inside at the panel.
There are devices listed for installation at either location, the key
difference being whether they are rated for installation before or
after the main breaker. The ones for use in a panel are installed by
adding a breaker that connects to the surge protector. There are
also some that come as a special breaker that have the surge protector
Key thing to keep in mind is that you want a short connection to a
good ground that is as straight as possible. That probably means
installing it outside would be preferable.
The protection in virtually all suppressors, service panel and plug-in,
uses MOVs. They are fast enough for any surge on incoming utilities.
Five nanoseconds is faster than the surge rise time (which I believe is
what Bub said).
Depending on what the "event" was, "whole house" and plug-in suppressors
may not provide protection. In particular "crossed" power lines.
Where is the connection to the earthing electrode(s). It is probably at
the outside disconnect. That is where the service panel suppressor
should be connected. You need the suppressor connected to the earthing
electrode system. That somewhat limits your options. If the service
disconnect is outside, the basement is not a service panel (there should
be separate neutral and ground busses. If installed at the basement
panel (panels?), the suppressor would have to have connections to both
hot busses, the neutral bus and the ground bus. The ground bus would
have to have a good, short connection to the earthing electrode system
(which is unlikely now).
Except for suppressors that are installed on the meter base (by the
utility) virtually all suppressors are downstream from the service breaker.
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
major 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.
The other consideration (in both guides), which is often missed, is that
the "ground" wire from the cable and phone entry protectors needs to
make a short connection to the earthing electrode system near the power
service. The IEEE guide says 10 ft is too long. If there is a strong
surge that is earthed in your system, the potential of your house
"ground" may be thousands of volts above "absolute" ground potential.
Much of the protection is that the power and cable and phone wires rise
together. That requires *short* ground wires. Another method is to run
the phone and cable through a special service suppressor, as in Bub's
post. That may not be practical if the suppressor is outside.
The NIST guide, using US insurance information, suggests most damage is
from high voltage between power and cable or phone wires. There is an
example of that in the IEEE guide starting pdf page 40.
Because the most common damage is high voltage between power and cable
or phone wires, a plug-in suppressor at high value equipment with both
power and signal wires may be a good idea. All interconnected equipment
must be connected to the same plug-in suppressor, and all external wires
to a set of equipment (power, phone, cable) must go through the
suppressor. Plug-in suppressors work by limiting the voltage from all
wires to the ground at the suppressor (also illustrated in the example
What you use depends on the risk and the value of what you are protecting.
I agree with others that your dog fence is not protected by a service
panel suppressor. You can have similar problems with a submersible well
pump, but many of the motors include surge suppressors.
They are dirt simple to install. They are attached at the service panel and
have three wires.
It's a small box (~4x4") that attaches to a knock-out on the side or bottom
of the service panel.
One wire, the green one, goes to the earth ground. The other two attach to
the screws on adjacent circuit breakers such that both legs are protected.
The WHSP will do its business LONG before a circuit breaker will trip and
You have this backwards. Whole house surge protection will normally
protect electronic equipment, as long as the surge comes from the power
lines. As much as possible, you want the surge protector *between* the
surge and the equipment. Always add surge protection for incoming phone
and cable tv wires also.
When a well pump is hit it normally takes a surge from lighting hitting
the wire, the well casing, or anything close by. This is between the
pump and the surge protector so the well doesn't get much protection.
I would definitely recommend a whole house surge protector in most
cases. I agree with the dog fence people, it would not have saved
you from the damage from the surge entering the via the dog fence
wire. While you say that had some kind of protection, apparently it
was not very robust as obviously a lot of energy got past it. My bet
would be that it did not have it's own direct connection to earth
The whole house protectors, properly installed, will limit surges to
400-600V, which should be enough so that equipment in the house can
survive. You can get good ones for $75-125. And if you can install
a circuit breaker, you can do the job yourself. Before I'd spend the
$400, I'd carefully check exactly what device they are installing,
check its specs, see how much it costs, etc. For that price you
should be getting a real good one.
Also, while I'm sure it can be debated, if the two panels are located
right next to each other and the connection point is short, say a few
feet, I would probably only install one.
For more complete protection, the whole house unit should be
supplemented with plug in protectors on sensitive equipment,
particularly eqpt that also connects to phone, cable, etc. You want
the type there that pass all those lines through it so that it can
clamp all those lines and limit the potential difference between them.
Whether it's worth it for 6 years depends on how frequent surges are
in your area, how much expensive eqpt you have, etc.
If that was actually true, reality would be very different than it
actually is. For one thing, nature would need to keep a database of
lightning hits, and check it every time.
Of course, nature does no such thing. The statement "Lightening never
strikes twice in the same place" is obvious nonsense.
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