VoIP Equipment Grounding [telecom]

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Thanks for reading this. I need information about grounding, and I'd
appreciate your help.

The IEEE 1100 standards have a lot of information on this topic, but
the printer versions cost hundreds of dollars, so I hope there's
someone in the TD world who can provide some less costly advice.

I was recently called to one of my customer locations, where the
Quintum AXM2400 VoIP endpoints had been damaged for the third of
fourth time by what the customer describes as "lightning".

As with previous visits, there was no sign of a lightning strike at
the site: no burned equipment, no reports of fire, no fire alarms, no
melter wire, no displaced cabling in the racks, no insulation burnt
off the wires. Most telling, to my mind, was the lack of damage to the
Mitek surge protectors that are used in place of bridging clips at the
"66" blocks where the dial tones from the Quintum VoIP adapters
appear. The UPS that powers the Quintum units has the usual surge
suppressors, and it's still putting out power and has no scorch,
smoke, flare, or other overvoltage marks.

I asked the site representative to show me the ground rod outside the
telecom room, hoping to find a broken connection or some other obvious
reason for the repeated callbacks. It turned out that there was no
ground rod: the telco room grounding leads, tied together in the usual way
at screw-down strips on the plywood backplane, eventually wound up in
a ground wire which went through the wall to the outside, up to the
eaves, around two corners, through another wall, around another couple
of corners, and into a three-phase electrical panel. The total length
of the ground is over fifty feet counting the interior legs, so I'm
wondering if a power surge or surges might have been prevented or at
least lessened by a shorter and/or more widely distributed ground.

So, the questions: what does the IEEE 1100 standard say about the
gauge and length of ground wires?

1. I've never seen a ground this long: is length unimportant if the
   ground admittance is within spec? If I take a "megger" to the site,
   what are the readings that are within the "good" range?

2. Are there limits on the number of devices placed on a single ground?

3. What's the "official" wire gauge requirement for grounds? The site
   has a mixture of #14, #12, #8, and #6 wires, with no obvious
   pattern: the main ground wire that exits through the wall appears
   to be #6, but I couldn't verify that.

Thank you in advance for your help.

--
Bill Horne
(Remove QRM from my email address to write to me directly)

Re: [telecom] VoIP Equipment Grounding
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Feel free to anonymize and stick in the digest - I'm out of practice
at that. I did COE Power ages ago, and this is how they did it.  There
are Good Reasons why they all have landscaping around the building -
trees, bushes and lawns...  You need a systemic solution.

Don't spend a ton of money on IEEE standards - Look at the grounding &
bonding rules in National Electrical Code.  That is available for far
less and applies everywhere just the same - Some cities like Los
Angeles write far stricter rules that override the NEC, call and ask
and they'll gladly tell you.

Other small towns or counties just say "We hereby adopt NEC 2014 (or
2011, sometimes even further back...) in total by reference as the
City Electrical Codes" and Boom, we're done.  Some take the middle
route and adopt it With Exceptions. Usually after somebody gets killed
by a loophole nobody could plan for...

And if it really is power surges, correcting and beefing up the
grounding network is the only true solution.  Because I've seen lots
of houses and businesses (for instance HOA Clubhouse with Spa and
Swimming Pool) with bad or totally missing grounds, no ground bond
between natural gas and master ground system, and they replumb with
Copper and leave the building ground bonds all attached "in common" to
the disconnected galvanized pipes...

Then the utility neutral line to the utility transformer (AL Wire is
notorious for burning clean off or corroding so it goes bad {Aluminum
Oxide} to a loose and megohm-resistance connection in a split-bolt but
looks just fine...), the ground rod resistance sucks, and you've got
over 100V of phantom power on that building ground.  And since they go
around the building and tie their Telco Ground common with the
building power ground, any surges can go backwards the same way they
go forwards.  ;-) It's a 30 or 40 year old building (Or more) what do
you expect?  Power works, they never touch it till it stops working.

I've gotten calls with reports of "swimmers getting zapped off the
pool ladder" because the building ground is hot, that pool ladder is
bonded through the pool grounds to that energized ground line, and the
pool water is an actual ground, and there's gradient current that can
actually kill if they get across it just right.  And if you don't make
a perfect path you Really Know It. Whooee!

Also happens in Marinas and Docks, and can kill swimmers next to a
boat or dock that is miswired or deliberately crosswired and no
functional GFCI protection, with hot hull fittings or steel conduit
under the dock dipping into the water.

Or you have very high ground resistance - sandy soil in a desert in
drought conditions, and a single 8' x 1/2" OD copper plated steel
ground rod in dry dirt right under the power panel might as well not
even be there at all.  The Utility Neutral line will cover that up for
decades, till it goes bad too.

Get a ground resistance tester and see what you've got - you drive a
few resistance reference rods out 10 to 20 feet and run it like a
Megger.  It'll tell the customer what they don't want to hear - but
they need to hear.

First step to a proper solution is to dig a trench around the entire
building at about 10' out from the walls, and put in a continuous ring
of at least #4 bare on IIRC a 100A service, if not bigger if the
building has a bigger power service - there's a chart in the back #2
for residential 200A service, #1 for 200A 1Ph Commercial, etc.  And a
chart for the minimum sizes and count of ground rods.

And the local utility and local Authorities Having Jurisdiction (IE
City or County Building and Safety) may be more stringent - it may
have been enough grounding when they built that shack as a supply
point for the local Telco workers 60 years ago, but it sure isn't
enough now that it's been converted into a mini Central Office and
they know it - and now you're having troubles.

You may be able to get the AHJ to cite the building owner for
substandard grounding and force them to get it fixed, or the Power
Utility has the Power of the Power Meter, they can pull the meter and
kill the building if it's unsafe, because they know they'll get sued
if someone dies.  "You have 60 days to get this properly bonded and
turn in the Permit sign-off sheet, or we turn off the power, because
Safety" works wonders.

Connect your ground loop to the building power panels, all other
utilities (water, Gas, etc.) and to the Telco main ground
bar. Compression C-taps OK, Thermite Welding more better but a big
pain in the keister. And check all your connections with that ground
resistance tester.

Splices and ground rods should be in handholes so you can find and
inspect them later.  They make handhole lids marked GROUNDING

Then put a tree well about every 10' and plant a ground rod and tie to
the ring, and put a sprinkler line connecting them all and put a
sprinkler head in that corner.  Dig out the sandy soil down about 6'
or so with a backhoe and dump in some real topsoil and a scoop of
Bandini mixed in, and plant a tree, or some bushes, or a lawn.

Place a sprinkler timer that runs those sprinklers at least a few
minutes a day, even after the tree is established just cut it to
minimum, and make it clear to the owners and to the city this is Not
Optional - you're watering the darn ground rods if nothing else.
Heck, if there's Reclaimed Water Mains available make them hook up to
them and buy a pile of the Purple Sprinkler Pipe and a bunch of the
"Reclaimed Water - Do Not Drink" signs.

And be sure to direct the downspouts, HVAC Condensate drains and the
water heater relief valve line into the closest tree wells too, water
is water.  If you have a surplus of water sources all in one place,
run landscape drains in Perf Pipe between the wells to spread the
wealth, and dump at the property line curb at the low end.

Now go check your ground resistance readings again, and I guarantee
it'll look a whole lot better.  Drive by every so often (or get the
phone number of the neighbors, and ask them to call you) to make sure
they didn't let it all die on you, or the troubles will start again.

--<< Anonymous >>--

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