Roque Lachica Jr on 25 Jun 2015 13:31:18 -0700

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Re: [PLUG] Home wifi access point & router recommendation

I'll remember that for the future.

On Jun 25, 2015 3:32 PM, "Keith C. Perry" <> wrote:
Very good point.  Most of these units just come with a standard DC "wall wart" i.e. no real ground.

Also it should mentioned that UPS' are NOT... I repeat NOT good surge protectors.  They can handle small power surges but NOT lighting strikes.  They are designed to fail when a large enough current  flows through.  Think of a light bulb- putting aside thermal wear, the filament can handle a certain amount of current.  Anything higher and it will burn out so, there will be an open circuit... which is good in this context.  However, when you're talking about a lightening strike there is more than enough current to ionize that air gap so, the circuit will close.  Now you have effectively a wire that the current flows through and fries anything that gets in its way, on its way to ground.  The time it takes for this to occur exceeds the ability for normal electrical protections of overvoltage conditions.

One of the things I have previously installed as part of my network and server power infrastructure were there brickwall devices.  I highly recommend them.

They are pricey- even the two port model (which have) but these devices are designed to take lightning strikes.  Basically its a big inductor which is a current device.  Simplistically that electrically means that current can't ignore it and jump somewhere.  It has to flow through it.  When it does... even with the awesome amount of current delivered by a lightening strike, the brickwall can safely sink that overflow to ground.

From what I understand hospitals use them and as we know hospitals have a ton of extremely sensitive electronics- NOT having clean and safe power is simply unacceptable for them.

After losing two servers in recent years, I finally moved my office away from UPS' in favor of these device for surge protection and another solution I haven't implemented yet for uninterrupted power.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Keith C. Perry, MS E.E.

From: "John Kreno" <>
To: "Philadelphia Linux User's Group Discussion List" <>
Sent: Thursday, June 25, 2015 2:16:09 PM
Subject: Re: [PLUG] Home wifi access point & router recommendation

The small consumer stuff lacks good grounding. Rarely do they have dedicated grounding. When you get transients often a common connection between devices will act as a ground path. In this case potentially the Ethernet connection. Sometimes it's not enough to completely destroy the electronics. Better grounding can help relieve the problem. Make sure your cable line shield is grounded to your electrical ground and make sure all your stuff has a good common ground. Also with inductance, the shorter your runs the better.


On Thu, Jun 25, 2015 at 1:50 PM, JP Vossen <> wrote:
On 06/25/2015 11:08 AM, K.S. Bhaskar wrote:
> What's peculiar is the failure - refuses to connect with the WAN (cable
> modem) and get an IP address.  The light on the cable modem flashes when
> I connect the cable to the router, so evidently there is physical
> connectivity, and the cable is good because it is working now with my
> old backup router. So, it must be a hardware failure on the NIC of the
> Buffalo N300 - most peculiar…

I lost a bunch of NICs to similar symptoms in a near lightning strike a
few years ago.  My wild guess was induction on my Cat5 cable plant.  One
unit had a multi-port NIC and I was able to just swap ports, so that one
was interesting.  Others were more of a pain.

Come to think of it, I lost the WAN port on a WRT54GL some months ago
for no reason I'm aware of, with exactly that symptom.  I just bridged
the whole Ethernet bus and used a different port; the way I have it set
up "WAN" doesn't matter.

JP Vossen, CISSP            |:::======|
My Account, My Opinions     |=========|
"Microsoft Tax" = the additional hardware & yearly fees for the add-on
software required to protect Windows from its own poorly designed and
implemented self, while the overhead incidentally flattens Moore's Law.
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John Kreno

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