Telecommunications Tech Blog April 2015
Do you put Lightning Protection on your
wait for damage and then put Protectors on?
The answer to including
lightning protection on new systems isn't all that straight forward.
I worked for a large Interconnect in Michigan for a while. They covered most of
the state, including branches in northern more rural areas where lightning was
Before I started working for that company I automatically included the best
Lightning Protection and AC Surge Protector I could get in every proposal, for
all the trunks and any OPXs (Off Premise Extensions) leaving the building.
Then the president of the Michigan company mentioned to me that they normally
offer lightning protection on every proposal, but they didn't push the customer
to take it - and their competition often didn't even mention lightning
protection, so it usually didn't go on new phone systems they installed.
That was shocking to me, until he told me that one lightning storm was like
having two more good salesmen selling new phone systems.
The company stocked equipment at most branches at levels that would get systems
back up and running pretty quickly after a lightning hit. They made quite a bit
of money on service calls to replace stuff hit by lightning. Most manufacturers
won't even try to repair electronics hit by lightning since so many components
get wiped out that troubleshooting is way too time consuming.
Sometimes it took a while to get paid for the parts and service call. Labor was
often on nights and weekends at a premium rate, and full new prices were charged
on the parts. Much more than the proposal listed for the costs for MACs (Moves
and Changes) for X years that went along with a maintenance contract.
A lot of companies don't have insurance coverage on their
phone system or computers for damage from lightning, surges or water damage from
a leaky roof. That often requires extra Electronic Equipment Coverage (EEC) on
the policy at an extra premium. A lot of the customers didn't find out about EEC
Coverage until after something happened.
There are definitely two ways to look at how you handle
Lightning and Surge Protection!
I've done lots of service calls to repair surge and lightning damage. I
witnessed the chaos that comes from having a phone system and computers knocked
out at a company. When we decided to manufacture Lightning Protectors about 15
years ago, we made what I consider the best Lightning Protection out
there. We call it MLP... Maximum Lightning Protection.
MLP Lightning Protector that goes on a 66 Block
We make them for a 66 Block, with a terminal strip for direct wiring, and a
modular version for POTS lines and station ports.
The components we use are beefier than anything else out there. We make them in
a number of low voltage ranges (for audio, data and digital phones), as well as
regular POTS lines and Station Ports, T1, T3 and Ethernet. Any pairs going
outside of a building that don't have lightning protection on them can bring the
surges into the phone system and cause damage if they're not protected properly.
There aren't many companies relying on special T1 Lightning Protectors for their
T1 lines. The phone company uses regular twisted pairs from the demarc, which
has either carbon or gas-tube protection that won't protect a T1 Smart Jack
much. It turns out that the Smart Jack, which the phone company provides, is
used as lightning protection for the phone system or other equipment that the T1
is going to. Most companies think that's OK since the phone company will replace
the Smart Jack for free, until they have to deal with the down time of up to 24
T1 (or 23 PRI) phone lines, or their data connection out of service. By the
second or third Smart Jack that acted as a Lightning Protector, they're calling
The protection that the phone company uses on CO lines going into a building are
either carbon or gas-tube. These react slowly to surges, and don't protect the
electronics in phone equipment very well. They were originally intended to
prevent a subscriber from getting fried while talking during a lightning storm,
and to prevent wooden houses from burning down from lightning brought into the
house on primitive telephone wiring.
Our Protectors are "Dual Stage"... Self Resetting Over Voltage
and Over Current protection.
Over Voltage protection uses electronic components to take any surge over
a certain voltage (like 270V for a POTS line) and send it to ground. Any
lightning protection needs a good ground, or it won't do anything. The second
stage of protection, Over Current, consists of self resetting electronic
fuses which open at 150ma. When the current comes back down the electronic fuse
In the old days some manufacturers used "Sneak Fuses" to protect a line from
high current. They always needed to be manually replaced after taking a hit.
Today, service calls are way too expensive to use a technician to replace a $5
fuse after a storm.
Over the last 15 years we've only had one report of our Lightning Protector not
saving the equipment. It was at a radio station on a mountain top. They sent the
Protector back and there was no damage to it. There apparently wasn't a good
ground going to the Protector. Without the ground the surge goes right through
the electronic components to the device you want to protect. With the good
ground as soon as the voltage gets to the protection value of the Protector, the
surge is redirected through the electronic components to ground, and the surge
doesn't get to the equipment being protected.
If you use a Protector rated for less voltage than is on the phone line it will
always be shorted to ground, and the line will be dead. An example would be
using a Protector made for 50V on a real phone line with 48V talk battery. It
will work just fine on outgoing calls, but when the 90V ring voltage comes in it
will short the line to ground immediately - which answers the line and stops the
ringing. The Protector will self reset, ready for the next outgoing call, or to
divert the next ring to ground on an incoming call - starting the cycle over.
There are some lightning and surge protectors out there that use MOVs (Metal
Oxide Varistors) to short the line to ground, rather than modern electronic
components. MOVs are known to eventually break-down and start shorting, in this
case to ground, at lower and lower voltages. That causes the line to short-out
until a technician replaces the Protector.
The failure mode for our MLP Protectors is to short to ground when it blows up
from something close to a direct hit, or a direct hit. At that point it will
never self reset since it's likely a smelly hunk of melted plastic - but it did
save the equipment by failing shorted to ground.
Click HERE to see our MLP
There is protection for POTS lines that will 100% guarantee that
the equipment behind it will never be damaged no matter what, good ground or
not. These devices have a short piece of fiber optics between the input and
output. Since lightning will never travel over the short piece of fiber, the
equipment inside the building can't be damaged by surges. But, while you can get
a POTS line or analog station port to go between the input and output, they
generally don't pass some types of message waiting and Caller ID, or CPC
(Calling Party Control) disconnect. Because the fiber device is locally powered
there is a possibility that the electronics in the device itself will be blown
up by the lightning, and the line will go dead to the equipment inside. It
will protect the equipment, but if it's blown up it won't reset
automatically - and the equipment it's protecting will be dead until it's
The biggest users of fiber optic protection devices are power plants, where the
AC voltage induced into the phone lines coming into the building can prevent
phone equipment from working - and severely shock anybody working on the
telephone wiring. For worker safety phone companies have a limit for induced AC
on a line of 50VAC, since anything more than that could shock a phone man
working on the pair. While something under 50VAC induced onto a phone line might
be safe for a technician, modern electronic phone equipment seldom works
correctly when there's over .5VAC (half a volt) on the line (normally measured
from tip to ground and ring to ground).
It would be impossible to use a normal protector made for a POTS line at a power
station since there could be 500VAC induced onto that pair from outside. The
500V would never get into the building if there was a 270V protector on the pair
- because the line would always be shorted to ground by the 500V on it.
Click HERE to see our
Grounding Tech Bulletin, which explains why what looks like a good ground
could be almost no ground at all
Click HERE to see our
Longitudinal Imbalance Tech Bulletin, which explains induced AC voltage
problem testing - and how to fix it