[TowerTalk] WHOLE HOUSE SURGE/LIGHTNING PROTECTION -resp. DAVIS RF Co.

Tue Jan 4 08:45:38 PST 2011

Hello TT'rs,  

There have been some good technicals and experiences pointed out in this thread.  I have sold PolyPhaser entrance panel devices to 
hams and businesses that have mucho dollars tied up in equipment such as audio processing, ISP's, etc.  The protection of this sort  is expensive, but it is a step tantamount to "extra insurance coverage", in that monetary insurance alone will not prevent major down time, lost revenue, or missed DX contacts due to damaged equipment and the time to replace it and/or if need be, getting the insurance proceeds first. 

Gary K4FMX, made an important point, "   "No matter how good a ground system you install the voltage on that ground
system will always rise above true earth ground during a lightning strike". 
Sometimes by many thousands of volts! This means that ALL equipment and
lines connected to that ground system must rise together to avoid damage.  "

I get calls for quotes to replace wire, cable, SPOE's, insufficient protectors, etc  etc  and I find that often when a single point ground was used, close to the station, what was missing was the return from that back to the entrance panel ground.  This is such a simple undertaking....usually a # 6 or # 4 THHN (check your code), which is a std. Home Depot item (DAVIS RF always tells you to get it at Home Depot, the best price and no shipping cost).   And you can simply run it on the ground, next to your foundation.  

  ALso, you never know when you can have a hit, somewhere down the utility line, away from your station, and a killer to your equipment even if no 
lighting attraction at your QTH. 

As the old saying goes, " you can pay me now, or pay me later."    HI  

73,   Steve,    K1PEK 

DAVIS RF Co.,  Div. of Orion Wire Co., Inc.

Wire, Cable, RF Connectors and wire aerial parts.  

LMR, Heliax, Eupen

Commercial / Military

Custom Cable Design

tel:  978-369-1738     Fax:  978-369-3484
www.DavisRF.com

> 
> Message: 1
> Date: Tue, 04 Jan 2011 06:36:14 -0600 (CST)
> From: David Robbins <k1ttt at verizon.net>
> Subject: Re: [TowerTalk] Fwd:  WHOLE HOUSE SURGE SUPRESSORS
> To: towertalk at contesting.com
> Message-ID:
> 	<901970865.1210116.1294144574457.JavaMail.root at vms231.mailsrvcs.net>
> Content-Type: text/plain; charset=UTF-8
> 
> 
> in the grand scheme of lightning protection going from 120v to 200v is MUCH better than going from 120v to 200kv or more.
> 
> 
> Jan 4, 2011 03:27:18 AM, gm3sek at ifwtech.co.uk wrote:
> 
> David Robbins wrote:
>> the most important function of a whole house or similar large arrester 
>> serving a building is to equalize the voltage between all the 
>> conductors so that all the equipment connected to it is as the same 
>> potential.
> 
> We don't truly mean "equalize" and "same potential" here.
> 
> When MOVs conduct, they do not crowbar their two terminals together to 
> equalize the voltages. They act more like bidirectional zener diodes, so 
> they attempt to limit the applied voltage *difference*... which can 
> still be quite large.
> 
> In a typical US home installation, the threshold voltage of the MOVs 
> must be well above 115V AC to ensure that the MOVs will not conduct at 
> the peaks of normal line voltage. When a surge arrives and the MOVs do 
> begin to conduct, the clamping action is quite 'soft' so the voltage 
> difference between the two lines can easily exceed 200V (depending on 
> the source impedance from which the surge arrives).
> 
> When seen against the grand scale of lightning voltages, 200V might 
> conceivably be called "the same potential". But the connected equipment 
> doesn't share that view - it still sees the 200V across its terminals.
> 
> 
> -- 
> 
> 73 from Ian GM3SEK
> http://www.ifwtech.co.uk/g3sek
> _______________________________________________
> 
> 
> 
> 
> Message: 4
> Date: Tue, 4 Jan 2011 06:30:30 -0800
> From: "Jim Thomson" <jim.thom at telus.net>
> Subject: [TowerTalk] Whole house  surge suppressor's
> To: <towertalk at contesting.com>
> Message-ID: <BFEAC5083387478983C99B51CADFB75E at JimboPC>
> Content-Type: text/plain;	charset="iso-8859-1"
> 
> Date: Tue, 4 Jan 2011 03:02:53 -0800 (PST)
> From: AI4WM Bill <ai4wm at yahoo.com>
> Subject: Re: [TowerTalk] Whole house  surge suppressor's.
> To: towertalk at contesting.com, Jim Thomson <jim.thom at telus.net>
> Message-ID: <221129.8587.qm at web57905.mail.re3.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
> 
> Jim,
> I agree with your statement about most consumer grade surge protectors.? Many cannot handle arc flash and the tremendous amount of energy from a strike.? Then many that could are not installed to correctly dissipate what they should.
> 
> Where I live FPL supplies whole house protection at the meter for a small monthly fee and they will pay for damage up to a given amount should their protectors fail.
> 
> After working in commercial radio and seeing the protection used as well as what PP&L used when I lived in PA I cringe at much of the chinese junk being sold as protection. Also as a former fire fighter I am very surprised we did not and do not see more fires caused by the cheap junk out there.
> 
> 73,
> 
> Bill
> 
> AI4WM
> 
> ##  what baffles me is most of these plastic encased  ' whole house protector's'  you see at home depot, etc,  all say to use a spare 40-60A  2-pole breaker in your main panel !    The Joslyn commercial grade units  all use
> a 20A-600 V  rated cartridge fuse... one per hockey puck size mov..inside the nema rated fireproof box.    I don't see the requirement  for a 40-60A breaker  for small size movs.   That's  just asking for trbl....no wonder they burst into flames.  They should be using an internal fuse in the protection box...and not oversized breaker's. 
> 
> ##  The standard deal for the commercial grade joslyn units is just two big puck size movs.... and each mov is wired  from each hot to neutral.  The main 200A panel  will have it's  neutral and GRND  bonded together... which by code... is the ONLY place you can bond the neutral and grnd together... via an internal cu strap.  IF  a sub panel is used... then the sub panel  will  NOT have it's  neutral and grnd  internally bonded.    Reason is... in any sub pane, all fault current  must travel from sub panel back to main 200A panel... via the grnd wire... and NOT  the neutral. 
> 
> ##  By wiring each MOV  in the joslyn arrestors  from  each hot to neutral.......... what u really have when u re-draw it is..... you have 2 x movs  nose to tail across the 240 line... with the center tap junction of the 2 x mov's grnded.  Then you are protected  from transients  from each hot leg to  neutral/grnd..and also  across the  2 x hot legs. 
> 
> Notice in the mouser catalog... these new small quarter /nickel size movs... all have 3 x leads on them these days.   The new style mov's have an internal fuse built into them.  The 3rd wire is what runs the led, etc..and tell's you that the mov is good ..or not.   The 3rd wire on these new style mov's is slightly offset  to one side.   Reason is..so they can only be inserted into the mating PC board one way. 
> 
> If the whole house protector is of the right type..and wired correctly, you probably don't require down stream mov's at all.   The 3 x way protection that you see in the arrl handbook  uses 3 x movs H-N , H-G  and N-G .     Whether all 3 x movs  are required..or just the H-N  is debatable.    Whether 1 or 3 x movs used, at least either install  1/3  correct size fuses  so you don't create a fire..... or better yet, use the new style movs  with the built in fuse.   The mov's  with the  built in fuse have another advantage.... they can't be overfused... or RE-fused.  Internal fuse blows, the mov is no longer in the circuit..and no chance of future mov explosions/fires.    You also don't have any protection.    
> 
> later.. Jim   VE7RF 
> 
> 
> 
Message: 7
Date: Mon, 3 Jan 2011 20:46:38 -0500
From: "Gary Schafer" <garyschafer at comcast.net>
Subject: Re: [TowerTalk] Fwd:  WHOLE HOUSE SURGE SUPRESSORS
To: "'Paul Christensen'" <w9ac at arrl.net>,	<towertalk at contesting.com>
Message-ID: <20110104014652.00FD91B60B74 at dayton.contesting.com>
Content-Type: text/plain;	charset="us-ascii"

I see lots of confusion on this subject. First we should define the
difference between power line surge trash and lightning. They are different
in the way that they are handled.

Power line trash is typically between hot and neutral. 
But since the neutral and ground are tied together at the service panel then
the power line trash is also between hot and ground as well as neutral.
An MOV across hot and neutral and hot to ground will keep all at the same
reference during the trash spikes. (almost)

There is nothing wrong with a 3-mode MOV device. 
It will keep hot, neutral and ground at the same potential (zero
difference)(almost) with respect to the line trash. 
A single MOV at this point, between hot and neutral, would allow a
difference in potential to ground at the equipment during trash spikes. This
of course depends on the distance the equipment is from the neutral/ground
bond in the main panel. The further away the greater the voltage difference
to the ground wire at the equipment. With the addition of an MOV from hot to
ground then the ground will have trash transmitted to it if it is any
substantial distance from the main power panel bond due to the impedance of
the long ground lead

Power line trash/spikes usually are not the problem of killed equipment
although they can be the source of noisy equipment. Lightning is the biggest
concern to do damage.

With a lightning strike whether it is a direct or indirect strike can cause
significant damage. 
Remember that lightning is always trying to find EARTH ground to equalize
itself.
Lightning unlike power line spikes can come in on the hot, neutral or ground
line. Some type of equalization is needed so that the strike energy does not
come into the equipment on the hot line and leave the equipment on the
ground line. That will cause damage to the equipment. Clamping all three
lines to the same level will keep the energy out of the equipment even
though the chassis may rise well above zero volts during the event. 3-mode
MOV's can accomplish this. A single MOV can not!

Where the problem arises is when there are multiple equipment ground points
with multiple pieces of equipment!
An example would be a computer in one room with a data cable running to
another computer in another room. Data cable shield bonded to each
computer's chassis and each computer plugged into their own outlets. Now we
have a loop between the two pieces of equipment with power being fed
individually to each. If the power is fed to each from the same circuit
there is much less chance of voltage differences between chassis.
Or a TV being fed power from an outlet and also connected to the cable TV
line. A place for the energy to enter and another for it to leave.

This gets back to our "single point ground system" that has been discussed
many times here. All power and other cables connecting to a piece of
equipment need to go first through a common ground/bonding point (single
point ground).

A whole house protector is a good idea but be sure to also bond all other
cables such as phone lines, cable TV, and your antenna cables etc to the
same ground point or very near where the whole house protector device is
installed. If you don't do that the whole house protector could make things
worse than not installing it at all because the whole house protector is
going to force the ground leads to your TV, radios etc. up to the same
potential as the hot lead carrying the lightning strike! If your antenna, TV
or phone cables are not referenced to the same place as your whole house
protector then there will be a difference of potential at your equipment.

Here is something to always factor into your lightning protection:
"No matter how good a ground system you install the voltage on that ground
system will always rise above true earth ground during a lightning strike". 
Sometimes by many thousands of volts! This means that ALL equipment and
lines connected to that ground system must rise together to avoid damage.

By the way, I haven't looked at whole house protectors in awhile but lots of
then used to be just a couple of leads to form spark gaps and were filled
with sand to quench the arc. Nothing fancy but effective.

73
Gary  K4FMX