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Re: [TowerTalk] whole house surge protectors

Subject: Re: [TowerTalk] whole house surge protectors
From: Barry <>
Date: Wed, 19 Sep 2007 16:52:43 -0400
List-post: <>
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: 
>>> Subject: [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
>  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
>  ector is based on an MOV, the 400V MOV is going to > dissipate about 4-8 MW, 
> or, 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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