I've been looking at whole-house surge supressors and in my travels I found
something interesting at the Intermatic web site. I noticed this device:
http://www.intermatic.com/?action=prod&pid ‰16, which looks very similar to
something we already have attached to our outdoor electric meter box.
Unfortunately ours has been painted over so I can't read the writing on it
to see if it is indeed a "secondary surge arrestor", but it's shape looks
exactly like this Intermatic unit so I'm guessing it is.
My question is, what does this device do as compared to the whole-house
surge supressor like the IG1240R (also sold by Intermatic)?
One reason I ask is that we had a damaging surge during a close lightning
strike when we first moved in (2001). The house was new in 2001 and the
device above was always attached at the meter box, so I'm assuming it's not
meant to stop lightning surges (either that or it's just not working <g>).
We lost our electronic sprinkler controller, a VCR, and an electronic phone.
The VCR actually smelled like it was burning after the lightning hit! (BTW,
the lightning was close, but did not hit our house directly. We never did
find any evidence of exactly where it actually did strike.)
If this is the case, how do people protect the expensive equipment attached
to cell towers, ham radio towers, TV and radio transmission towers? I have
to imagine these towers get their fair share of lightning strikes. I can't
see the TV stations unplugging their transmitters atop the Empire State
building every time a thunderstorm approaches. <g>
My house (a 150-year old farm house) has a metal roof with two lightening
rods sticking up, and two metal cables running down over the roof and buried
in the ground. Since I'm up on a hill I am sure It's been hit more than once
in the 21 years I've lived here, and there's never been any lightening
'Whole house' protectors are secondary protectors. The
primary protector is that utility transformer earth ground
wire that is so critical to household protection.
Surge protectors do not stop, block, absorb, or filter out
surges. They do as Franklin demonstrated in 1752. He
intercepted lightning that sought earth ground through a
church steeple. Lightning will also chose the shortest path
to earth ground by striking AC power line and using paths,
destructively, through appliances. But effective protection
from direct strikes has long been proven. Lightning seeks
earth ground. The secondary protector shunts (connects,
diverts) lightning to earth IF located at the service entrance
AND IF if it creates a less than 10 foot connection to central
Therein is the protection. Not the surge protector. Earth
ground is the protection. Many locations have sufficient
grounding IF only installing an eight foot ground rod. How
good is the earthing? Geology is a major factor. Some will
install halo grounds around a building just so that they need
not discover the single earth ground rod is not sufficient.
What is that attachment on meter box? If it is a surge
protector, then it must have a connection from every incoming
utility wire to earth ground. If it is an effective surge
protector, then that connection will be less than 10 feet and
meet other earth connection requirements.
Damage is most often due to insufficient earthing. Many
places need very little earthing to be sufficient. Others
require a more comprehensive system. But every incoming
utility, including phone and CATV, must connect to that earth
Described is a classic example of AC electric surge. Surge
sought earth ground. It found earth via sprinkler system,
VCR, and base station to a portable phone. Notice every
damaged item had both an incoming path from AC electric and an
outgoing path to earth ground. For example, incoming on AC
electric, through VCR, and outgoing to earth via cable.
Incoming on AC electric, through base station, and outgoing to
earth via phone line.
Phone lines already have a 'whole house' protector installed
in the premise interface box (often labeled NID). But again,
the protector is not protection. Protector, provided free by
telco, will only be as effective as the protection connected.
That surge protector will only be as effective as central
Too many see surge protector and think that is surge
protection. Then when damage results, they will say, "No
surge suppressor is going to protect you from a close
lightning strike." Ironic that the better a surge protector,
then the less warranty offered. The benchmark in surge
protection is Polyphaser - who offers no warranty. Their
products and application notes are legendary:
Application notes don't discuss their products. Notes
discuss the most critical function of a surge protection
'system' (which is why that ground from utility transformer
is so important for the primary surge protection). Another
less technical discussion about earthing is found in the
newsgroup misc.rural entitled:
Storm and Lightning damage in the country 28 Jul 2002
Lightning Nightmares!! 10 Aug 2002
http://tinyurl.com/ghgv or http://tinyurl.com/ghgm
Even very little earthing can massively increase surge
protection. But the bottom line remains - a surge protector
(the science) is only as effective as its earth ground (the
You suffered surge damage because the strike found a better
path to earth ground via household appliances. All appliances
already have effective, internal protection. But that
protection was overwhelmed because there was no effective
connection to central earth ground at the service entrance -
where utilities entered. You require the 'whole house'
protector and earthing must be evaluated to, at minimum, meet
or exceed post 1990 NEC earthing requirements.
Vinnie Murdico wrote:
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