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Re: [TowerTalk] whole house surge protectors

To: <>
Subject: Re: [TowerTalk] whole house surge protectors
From: John Elsik <>
Date: Wed, 19 Sep 2007 15:06:10 -0600
List-post: <>
It appears I need to do more shopping for the AC protection.
Don't happen to know the GE model number do you?
John wa5zup

> Date: Wed, 19 Sep 2007 16:52:43 -0400> From:> To: 
>> Subject: Re: [TowerTalk] whole house surge 
> protectors> > I had the ICE suppressor on my mains. I had a lightning strike 
> earlier > this summer and the internal parts of the ICE box were fried. The > 
> electrician who inspected the house and did some repairs said it > probably 
> saved us from much more extensive damage (radios, computer, > VCRs, TVs, etc. 
> were dead.) He replaced it with a GE unit that has a > quicker response time 
> and greater Joule rating, and was more expensive> Barry W2UP.> > John Elsik 
> wrote:> > I have been reading this with great interest. I am installing a 
> ground system now. I was going to use an I.C.E 330 for the AC mains (whole 
> house). Would that be adequate? Something is better than nothing. It looks 
> like it is a shunt type also.> > > > John wa5zup> >> >> >> > > >> Date: Wed, 
> 19 Sep 2007 10:34:55 -0700> From:> To: 
>> Su
 bject: [TowerTalk] whole house surge protectors> > I've been doing a bit of 
browsing> Most of the whole house protectors are shunt mode (which, by the way, 
> can actually cause some problems, making things worse)> > Intermatic 
IG1240RC> Leviton 51120-1> Panamax gpp8005> Siemens various models> > etc.> > 
In any case, a shunt mode suppressor will also suppress transients > 
originating within the house.> > There is a case where they will be of less 
effectiveness.. if you have a > transient induced on the branch circuit between 
the panel and your load, > then the transient propagates both directions, and, 
depending on the > relative lengths of the wire, it will get to the load before 
it gets to > the clamp. Once the clamp goes into effect, an inverted transient 
gets > reflected back, so you can calculate the maximum width of the > 
unsuppressed pulse. (you could use something like> > >> > > 2 ns/ft as a > 
propagation speed... so for a 100 ft run, with the transient induced > next
  to the load (or downstream from the load), you get half a > microsecond or so 
before the voltage is clamped.> > > If the transient is induced on a branch 
circuit other than the one your > load is on, the suppressor is between the 
transient source and your > load, so it would clamp the transient before it 
arrives at the load.> > If you put a point of use transient suppressor *with a 
higher voltage* > than the whole house protector, it will take care of the half 
> microsecond impulse before the whole house protector kicks in, and won't > 
have to absorb as much energy.> > FWIW, statistics show that most transient 
damage occurs from transients > originating outside the house, typically from a 
lightning strike or MV > line / LV line fault somewhere (MV = 10-30kV, LV = 
120,240,480V). That > makes the rise time of the transient much slower (it's 
low pass filtered > by the power line), and a> ls> > o makes the whole house 
protector more > effective.> > In the event of a MV/LV short
  (the only kind of line transient I've had > personal experience with in 
Southern California.. we don't have much > lightning here), you've probably got 
a significant overvoltage that > lasts 8-10 milliseconds or longer (until the 
MV breaker trips or fuse > blows). You'd have to hope that the surge suppressor 
can hold on that > long without blowing its internal fuses. Or, ideally, it 
would short, > and trip your main breaker. Since most of these whole house 
protectors > have energy absorptions in the few kilojoule range, I'm not very > 
sanguine about their ability to protect against this kind of fault. > Figure 
the case of a 14.4kV feeder shorting to the 240V drop into your > house (this 
has actually happened to me). If the series impedance of > the feeder, through 
the drop, into the grounding system, is on the order > of an ohm or so, the 
fault current is around 10-20kA.> > If the surge pr> ot> > ector is based on an 
MOV, the 400V MOV is going to > dissipate about 4-8 MW, o
 r, 4-8 kJ/millisecond. If it takes a half > cycle for the breaker to trip/fuse 
blow, that's 8 ms, and about 50kJ > (which is why things literally explode when 
this happens).> > A surge protector based on a spark gap, which, once it fires, 
has a much > lower clamping voltage, will dissipate less energy in the 
protector, so > has better survivability.> > 
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