[ale] Should I ground a ethernet switch?

Sat Aug 10 17:21:16 EDT 2013

On Sat, 2013-08-10 at 15:53 -0400, Michael Potter wrote:
> Just bought this switch from Fry's because my old switch was zapped by
> a lightning strike.
> http://www.amazon.com/Netgear-ProSafe-5-Port-Ethernet-Desktop/dp/B00002EQCW
> 
> 
> It has a grounding tab.

I've got a couple like that and have never bothered.
> 
> I cannot find any recommendations on the Internet on the benefit of
> grounding the switch.  One reviewer on Amazon said it was for
> electrical noise isolation.  I don't care about noise isolation,
> however, I do care about avoiding more damaged equipment.
> 
> 
> So, my questions are:
> 1) Is there a benefit to grounding the switch in regards to avoid
> "getting zapped" again.

Probably not.  It may convey some protection but there will always be a
level that is going to get you.

> 2) What is the easiest way to ground it?  Can I just salvage a three
> prong plug and use the ground wire while safely terminating the live
> wires?

If you really want to and it's not conveniently near a grounding
conductor like the earth buss in a panel (I have one in my structured
wiring panel that's braid grounded to two earth ground rods through the
basement floor near my breaker panel) then you could just ground it to
another chasis that has a 3 prong cord or ground it to the center screw
of an outlet cover.  When you consider the induction of the wiring
between that and the panel and your "true earth ground", it's probably
not really worth the effort in a residential environment.
> 
> The strike also took out my router, cable modem, receiver, and
> ethernet port on my printer.  I am also having comcast out to replace
> their lightning arrestor.  

Most of the time, it's a common mode strike and the EMP effects are
truly amazing.  Years ago, I did a talk titled "Tales from Ground Zero -
Lightening!" for AUUG.  It documented a direct lightening hit we took on
the house way back in the 90's that caused switches and breakers to
explode and popped chunks of concrete from the basement floor and our
pool deck and what we did to recover.

Make sure your surge protectors protect ALL THREE WIRES!  Don't cheap
out or whimp out and get the good stuff with the guarantee's.  More
joules == better.   KEEP the warranty cards and receipts!  When
something blows, it's cheap additional insurance.

We had a whole house bi-phase 220VAC surge arrestor wired right into the
panel.  (Mine is an Intermatic ElectraGuard and I highly recommend one.
If you are NOT COMFORTABLE doing your own wiring, an electrician will be
well worth the money to install one for you.)  Plus I had large UPS
units with surge arrestors plus surge strips plus the transorbs in the
power supplies themselves on my servers.

Results:  Not a single hard drive failure or failure of purely internal
components.  Blew ethernet cards, ISDN TA's, ethernet switches, video
cards, and PS/2 ports.  Most of the motherboards came right up and
booted but could find no mouse or keyboard ports (and occasionally had
no video).  Anything with a wire hanging out like an antenna got nailed
and nailed good.  Didn't loose a single hard drive or byte of data.
biggest PITA was the EMP, when it hit the basement, magnetized my metal
tables and desks and it took me a good month to demagnetize everything
to the point where I could move my (CRT) monitor without it changing
color and looking like it had leprosy (LCD's are so much nicer that
way).

My stereo in the living room with the long speaker wires (some of which
drove speakers on our deck) was plugged into a surge strip but the
speaker wires picked up the magnetic field from the discharge.  When I
pulled the cover off the amp, I noticed there were missing traces on the
power supply PCB and the top cover was painted with vaporized copper.
Destroyed a couple of ground fault interrupters and the garage door
opener (just a simple circuit board replacement, though).

I now have Toslink fiberoptic cable in the house for the sound system
audio buss and no speaker wires exit the building.

I consider switches and external components to be expendable.  When you
are dealing with a lightening hit, all bets are off.  You just do the
best you can and expect to replace those sacrificial, expendable
components.

> I am also putting a surge suppressor
> (http://www.amazon.com/Monster-MP-AV-800-PowerCenter/dp/B00003CWDH/)
> on the coax connection to the cable tv box, and
>  a surge suppressor
> (http://www.amazon.com/APC-PNET1GB-ProtectNet-Standalone-Protector/dp/B000BKUSS8/) on ethernet cable between the cable modem and the router.
> 
Seriously consider one of these babies...

http://www.amazon.com/WHOLE-LIGHTNING-PROTECTOR-Spike-Ender-Suppressor/dp/B003Z9S974/ref=sr_1_7?ie=UTF8&qid=1376169028&sr=8-7&keywords=whole+house+surge+protector

http://www.amazon.com/Intermatic-IG1240RC3-Type-2-Protection-Device/dp/B003NVLWN2/ref=sr_1_2?ie=UTF8&qid=1376169123&sr=8-2&keywords=whole+house+surge+protector

http://www.amazon.com/Leviton-51110-1-Protection-Commercial-Residential/dp/B002VJKAZS/ref=sr_1_3?ie=UTF8&qid=1376169184&sr=8-3&keywords=whole+house+surge+protector

Those are all newer units than what I have.  Mine is now over 20 years
old and well worth the investment.  It's can't protect you against a
true 3 wire common mode surge, but nothing can.  But, I've taken some
NASTY common mode hits and I've not lost a thing to a differential mode
spike in that entire time.  Must be doing something right...
> 
> -- 
> Michael Potter
>   Tapp Solutions, LLC
>   Replatform Technologies, LLC
> +1 770 815 6142  ** Atlanta ** michael at potter.name  **
>  www.linkedin.com/in/michaelpotter
> 
Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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