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Re: [TowerTalk] Whole house surge suppressor's.

To: "Jim Thomson" <>, <>
Subject: Re: [TowerTalk] Whole house surge suppressor's.
From: "Mark Robinson" <>
Date: Mon, 3 Jan 2011 09:54:37 -0500
List-post: <">>
The surge suppressor in the link looks a bit cheap and small for a whole 
house. I would think something like that should be put inside a grounded 
metal box to contain the fire and sparks

Mark N1UK

----- Original Message ----- 
From: "Jim Thomson" <>
To: <>
Sent: Monday, 03 January, 2011 7:11 AM
Subject: [TowerTalk] Whole house surge suppressor's.

> Hi Dale.
> I've been in the fire service for 27 years now and I can't tell you the
> number of surge suppressors of the type that are typically installed on
> a 1/2" or 3/4' knockout hole* *that created
> the structure fire that we were responding to.  On a couple of
> occasions, I've seen them violently shoot green flames out of them in
> every direction as they burned themselves to a cinder.
> My power company installs the meter base style suppressor which places
> it outside of the structure the majority of the time.  I'm sure that's
> probably what you're also looking at.
> 73,
> Jon Pearl - W4ABC
> ##  The Joslyn brand surge protector's are used by the 10's of thousands 
> by telco's  across NA.
> They are mounted below, or close by a main panel.   Conduit  between main 
> panel +  protector.
> The protector's we used at work, were all in steel  enclosures, and those 
> things  were latched
> shut tighter than a drum.   Each of the two  [ 3  movs used for  3 phase] 
> huge movs  are wired
> between hot and neutral [ ditto with 3 -phase].   Each mov had a 20A slow 
> blow fuse in front of it.
> [600V rated... big cartridge fuses.. like the .375" to .5"   x 2" long 
> variety]
> Output of each fuse feeds a  neon.  Output of neon wired to same neutral. 
> A 4pdt relay..with a 120 vac coil
> is also used... one per mov.   120 vac coil wired between output of fuse 
> and neutral.
> ##  OK, with everything normal, all the neons are lit green.    If one or 
> more MOV's  shorts out, the mating fuse
> that feeds it blows open asap, and MOV is  now out of the circuit. 
> Associated neon also goes dark.   Mating
> 120 vac  dpdt relay  also drops out..... bringing in an alarm to the alarm 
> center/NOC etc.  All the relay's of course,
> in normal operation, are always operated 24/7..... except when a mov fuse 
> blows open.
> ##  I never saw one of those joslyn protector's  ever catch fire in 34 yrs 
> I was there. [ no equipment failures  from
> lightning, transients/spikes/surges either].   As long as they are fused 
> correctly,
> I don't see how the mov could burst into flames.   Even if it did, none of 
> it would get past the steel box.  Those box's
> were sealed very good, with a pair of real heavy duty latchs.  They were 
> not like a regular steel electrical box either.
> These things were water proof, fire rated  nema box's.   The seal design 
> was the best yet.   If they were the slightest fire hazard,
> the insurance co  would have been reading us the riot act.  [ factory 
> mutual in the US  is the main insurance co for most of the telco's
> in the usa + canada.]   In some parts of Florida, etc, home insurance co's 
> will insist that whole house protector's are employed.
> Insurance co's  were getting tired of paying out claims in lightning prone 
> areas.
> ##  I have seen some of the whole house protector's..sold at home depot 
> etc.. that use way smaller mov's.... and contain
> no internal fuses... but use a spare 40-60A  breaker position on the main 
> panel.  The box's  they use  look flaky to me.  They also
> use plane romex, etc,  from main panel to plastic box... and no conduit.
> Later... Jim  VE7RF
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