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I'm fishing for ideas - lightening protection

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tkamiya:
Quality of any type of lightening protection varies widely.  I've taken few a part.  Just a couple of MOV, MOV with inductor, and nothing at all.  Coaxial type tends to depend on spark gap.  By the time enough voltage builds up to jump the gap, the equipment is toast.  By the way, MOV is no match for lightening induced transients.  Some of them do good job against other appliances generating spikes.

Yes, I've lost few things to lightening.  At a different location, I lost half of an apartment full of appliances.  At this location, few network ports, gateways, etc.  Electrical power source is fairly robust.  I have layers of protection, and in this area, wires are underground.  Somehow, cable TV infrastructures are rather susceptible.  That may change when fiber optic spreads to my area.

Either way, I don't want to depend others doing the right thing.  I do want my own protection which I can trust.  I have a lot more to lose.  Lab full of equipment and over a dozen computers all networked together.

I forgot about Polyphaser.  They are quite expensive but their reputation is next to none.  Thank you for suggestion.  Problem with this type though is ground connection.  Good ground is on the other side of house, and code calls for ground entrance be done at one location only.  To be effective, Polyphaser needs to be installed close to my modem with short low impedance ground.  I'll figure this out.  There got to be a way.

MarkF:
I will put forth a resource (Mike Holt on the NEC) you can refer to:
   https://www.youtube.com/user/MikeHoltNEC/videos

What I have gathered from his videos is that ALL the systems inside your house should be tied together.
With ONE and only ONE connection to an outside ground.

The goal is that you want to eliminated voltage differences inside by a lighting strike.  If you have multiple outside ground rods, a lighting strike will create a voltage potential between them which will come inside and create a potential between systems inside.

One example:



I find these new GMOVs from Bourns very interesting:
   https://www.digikey.com/product-detail/en/bourns-inc/GMOV-20D111K/GMOV-20D111K-ND/10054803
   https://media.digikey.com/pdf/Data%20Sheets/Bourns%20PDFs/GMOV_Series_DS.pdf

engrguy42:

--- Quote from: tkamiya on June 16, 2020, 11:54:17 pm ---Quality of any type of lightening protection varies widely.  I've taken few a part.  Just a couple of MOV, MOV with inductor, and nothing at all.  Coaxial type tends to depend on spark gap.  By the time enough voltage builds up to jump the gap, the equipment is toast.  By the way, MOV is no match for lightening induced transients.  Some of them do good job against other appliances generating spikes.

Yes, I've lost few things to lightening.  At a different location, I lost half of an apartment full of appliances.  At this location, few network ports, gateways, etc.  Electrical power source is fairly robust.  I have layers of protection, and in this area, wires are underground.  Somehow, cable TV infrastructures are rather susceptible.  That may change when fiber optic spreads to my area.

Either way, I don't want to depend others doing the right thing.  I do want my own protection which I can trust.  I have a lot more to lose.  Lab full of equipment and over a dozen computers all networked together.

I forgot about Polyphaser.  They are quite expensive but their reputation is next to none.  Thank you for suggestion.  Problem with this type though is ground connection.  Good ground is on the other side of house, and code calls for ground entrance be done at one location only.  To be effective, Polyphaser needs to be installed close to my modem with short low impedance ground.  I'll figure this out.  There got to be a way.

--- End quote ---

Not sure why you say an MOV is no match for lightning induced transients. It's what your power company uses to protect zillions of $$ of equipment from lightning and other transients. There's probably one on the primary of the transformer on the pole feeding your house. They're designed to protect against lightning. There's a absolute crap-ton of stuff out there describing their use. For example, here's a nice paper from Littelfuse:

https://m.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_varistor_catalog.pdf.pdf

But hey, whatever you want to believe is up to you.

tkamiya:
Referring to Mike Holt's web page.....

Yes, that IS the reason why I said what I said.  It goes something like this.  You have two sides to the house.  South (S) and North (N) for sake of easy conversation.  Your electrical entrance is on S and your ground is S, and ground enters house from S.  At the point, neutral wire is bonded (connected) to the ground.

When lightening hits somewhere near S, ground potential rises.  Neutral side of electrical outlet potential rises as well by the same mount.  It's no longer at zero potential.  It's elevated by quite a large amount.  Then it propagates from there inside the house.  In the mean time, the lightening energy spreads via ground separately.  By the time it reaches N side, it's less.  Ground is conductive but not as good as solid copper wire. 

Now, if you happen to have another ground rods on N side, potential will rise, according to the ground level at that point.  Now, you have a problem.  Your electrical wiring has risen by larger amount than N side ground.  There is a difference in potential.  Which will cause damage.

This is why I'm being so careful.  I could make situation worse by randomly burring grounding rods.  One method to avoid this is to surround the house with thick ground wire and place grounding rod all around the house.  But I can still only enter the house from one point.

I didn't read about this on web.  I do hold an electrician's license from Japan.  I was professionally trained.

EEVblog:
http://www.eatoncorp.com.au/ecm/idcplg%3FIdcService%3DGET_FILE%26allowInterrupt%3D1%26RevisionSelectionMethod%3DLatestReleased%26noSaveAs%3D0%26Rendition%3DPrimary%26dDocName%3DPCT_361252

MOV's can be used in CAT B and CAT C locations.

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