The type that looks like a circuit breaker that fits your panel (called "plug on
in the link below). These have the shortest possible leads so they how a low
impedance to a surge,
but may not last as long as the larger ones that mount through a knockout. You
could use the larger
style if you also want to protect CATV and phone lines through the same TVSS,
and you can probably
find those types at your local home center.
Our local utility leases TESCO Watt Hour Meter Base Surge Arresters -- the
meter is pulled and it is plugged into the meter socket and grounded then
the meter is replugged into it. Tesco also has units to wire into the main
panel for both 1 phase and 3 phase services. http://www.tesco-online.com /
Others make similar equipment too.
For starters, make sure your ground is of good quality - a good
electrician can measure the conductivity of the soil around your ground
rod, measure the difference in potential between the soil and your
ground wire, etc. Make sure you get someone who understands that
grounding for lightning/surge protection is more demanding than just
safety grounding; many electricians I've called know only how to meet
code, which covers only safety grounding.
Lightning has high-frequency components that behave very differently
than the 60-Hz sinewave of normal AC, and long or poor-quality grounds
can be fine for safety, but useless for lightning. As I understand it -
and I'm not particularly electrically inclined, as diespammer can tell
you - the surge suppressor is essentially in parallel with your breaker
panel, and if a surge hits, the suppressor tries to become a better path
to ground than your panel, so that the surge is bled off straight to
ground. But if your ground isn't high-quality enough, or the rod is too
far from the surge suppressor, the suppressor will be useless.
I have a thousand-dollar surge-protection system that failed to prevent
several thousands of dollars in damage during a nearby lightning strike,
probably because my ground rod is 40-50 feet from the surge suppressor,
and may not be buried enough or in conductive enough soil. (My "main
panel" doesn't exist, electrically speaking; my outside service entrance
has a long run to my two "main panels" which are really wired as
subpanels due to code requirements, and the suppressors were attached to
As for the brand of suppressor, every lightning-protection company I've
talked to recommends a different brand, so I'm not sure it matters that
much. I've heard recommendations for Square-D and Leviton among others.
I currently have a Cutler-Hammer, which one company says is not high-
enough quality, but I'm not sure if that's true or just typical we-
And to state the obvious, if you're going to install it outside, make
sure it has a weatherproof enclosure available. Outside may be the best
choice, though, since that will certainly provide the shortest path to
ground. My next one will probably be outdoors.
A surge suppresser is just that, a suppresser for voltage surges or
transient high voltages that come in on your electrical service line.
This is not necessarily the same as the voltage surge resulting from
lightning. If the lightning strike is distant from your home and the
surge just results in a transient over-voltage on your line it will
probably protect you.
However, if you are close to the lightning strike it's another ball
game. Recall that current passing by a wire will induce a voltage in
that wire. This is usually thought of as a current passing through a
coil of wire as in a transformer but a coil isn't needed. A straight
wire in a magnetic field is enough if the magnitude of the current is
high enough. Lightning strike currents can reach millions of amperes.
The consequence of this is that damagingly high voltages can be induced
in wires within your home, 120 volt lines, CAT-5 cables, speaker
cabling, etc. The surge suppresser in an entrance panel can't do much
to protect against these surges. The best you can do is to protect as
close as you can at each device that is at risk.
Jay Levitt wrote:
RB misrepresents facts and posts classic urban myths. If
nearby lightning creates currents in wires, then how much
current. He cannot answer that. Not enough current to even
overwhelm protection that already exists in all appliances.
Specifications on the 'whole house' protectors list numbers
rated for earthing the direct strike. That is what a 'whole
house' protector is for - earthing the direct strike so that
damage does not occur inside the building. Earth the
transient so that internal electronic protection is not
Jay Levitt has accurately summarized what protectors (or
suppressors or TVSS) do. Make a temporary connection to earth
ground. Earth ground - the quality of - determines how
effective a protector would be during the direct strike.
Suppressors do not stop, block, or absorb transients as RB
would have us believe.
Joules is a benchmark for life expectancy of a suppressor.
The suppressor is equivalent to a switch that connects earth
ground to that potentially destructive transient. More joules
means life expectancy of that 'switch' (the suppressor)
increases - exponentially.
Some effective 'whole house' protectors were listed in a
previous post in newsgroup misc.rural: "telephone
wire/lightning strikes" on 30 Sept 2003 or
Introduction to surge protectors and surge protection (they
are separate items) is in "RJ-11 line protection?" on 31 Dec
2003 in pdx.computing, or http://tinyurl.com/2hl53 and
"Opinions on Surge Protectors?" on 7 Jul 2003 in the
newsgroup alt.certification.a-plus or
Check specs, look for High Joules and reaction time in nanoseconds.
Instantanious is best, 0 Nanoseconds. Tripp makes strip units with Zero
response time but not a whole house unit. Tripp offers a good warranty.
Whole house units vary. There is also a lightning arrestor but i dont
now who makes it. Start with your grounding , and strip units try
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