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One of the problems which faces anyone trying to work on phone wiring
for their home or business is the wire at the Network Interface or Lightning Protectors. Here are examples of each.
Above is an example of a Network Interface (NI) you're likely to find
on your building. This one was installed by Ameritech here in Illinois before the company was bought by SBC. There
are numerous physical configurations of Network Interfaces but yours should look something like this and will usually say
on it "Telephone Network Interface." So you can't go too far wrong.
This particular NI is fed by a buried drop which enters the Interface
from below via the gray plastic conduit on the right.
This photo above is of a housing for the older type of lightning protectors
in use before the advent of Network Interfaces. It will usually also have an embossed Bell System emblem on it for identification
purposes. You will also notice that this device, like the NI in the picture above, is fed by a buried drop wire through
a plastic conduit. Both of these devices can be fed by either buried or aerial drop wires. In the case of aerial
wire, there will be no conduit and the drop wires will enter the device through the same port as the conduit.
Above: This is what is inside the protector housing shown in the
second picture. This is a two line protector. The four hex nuts you see in the center of the protector with
the Western Electric "WE" in the middle of them are the actual protection units. In this particular device, the
protection units are the older type which consists of a set of carbon and porcelain blocks sitting in front of a spring which, itself, sits on a ground plate at the rear of the protector. On the
newer type of protection units for this type of protector, the protection device is made up of a gas-filled cartridge also
sitting in front of a spring. The difference between the two is easy to tell. The top of the hex nut on the gas-filled
units is painted white whereas the older type is plain brass. The binding post at the bottom center of this protector,
to which is attached the silver ground bond for the buried drop, is for a 14 gauge, solid copper, ground wire which shunts
current to earth upon the presence of a high voltage hit to one or more of the binding posts on the side of the unit.
The ground wire, with its gray insulation, can just be seen to the left and behind the drop ground bond clamp.
Above: This is an example of a very early lightning protector and
is probably about 75 years old. It consists of two binding posts at the bottom of the unit to which the drop wire was
attached. These binding posts are attached to upper posts by fuses. You will also note that these two long, red
fuses have copper straps across them which effectively circumvent the fuses so that even if they blow, service will continue
across the straps to the upper binding posts to which the building's internal wiring would have been attached. I never
did find out why the phone company in later years strapped out the fuses unless they were blowing out regularly and contributed
little to effective safety. The upper portion of the unit not only contains the binding posts to which the inside wire
was attached, but, the center binding post at the very top was provided for the ground wire for the carbon and porcelain protection
units which were housed inside the black screw cap in the center. The brown, cloth covered ground wire can be seen at
the very top of the protector and it is cleated to the floor joist to secure it. The ground was located in the
same area of the protector as the inside wire so that access could be had for use with the inside wire as well. The
early inside wire consisted of three leads - tip, ring and ground. In later wire, when color identifiers were used,
besides red and green for the tip and ring sides of the line, the ground lead was yellow. The ground was used for
the ringer circuit on party lines. Without it, the phone wouldn't ring though you could talk over the line. The
entire lightning protector sits on a thin asbestos plate or sheet. Immediately below it in this picture can just
be seen the white porcelain clamp which secured the drop wire to the joist. This protector was no longer in use
when the photo was taken.
Another common type of lightning protector you may encounter, either
indoors or outdoors in a metal cabinet, is the 98 type protector shown immediately below.
This protector works the same way as the one above it. In the picture
below, the black cap has been removed and you can see the arrangement of the carbon and porcelain blocks which are usually
removed when the phone company installs an NI on the outside wall of the house. These blocks rest on the center
brass post which is grounded. This protector is still active as an NI has not yet been installed.
The pictures below are of just the carbon and porcelain blocks along
with their backplates which rest on the ground post.
Below, another view of the blocks from their side.
It might seem hard to believe but this protector example immediately
above replaces the much bigger ones above it. This type of protector is still in use today as is the two pair protector
shown earlier. In the 1980s, the phone company started using a gas-filled protector which did not have removeable protection
units. In the presence of high voltage, this gas ionizes and provides a path to earth (or ground, if you prefer).
When the voltage is removed, the protector returns to its normal state. The gas-filled units have a great advantage
over the carbon and porcelain protection units. When the carbon and porcelain units blew, they had to be replaced.
In the presence of high voltage, the carbon blocks under the pressure of the spring would be moved to earth after the restraining
glue melted. It was a one-shot deal. But this left the phone line either entirely unuseable or, if only a minimal
amount of arcing occurred across the carbon blocks, the line voltage used to talk over would also try to arc to earth causing
static and noise on the line. Sometimes it would be enough to shunt the ringing current to earth and the phone wouldn't
ring, or, it might ring once and trip the central office equipment which thought the phone had been picked up when it hadn't
or, depending upon the amount of moisture in the air, the phone might ring this time, but, not the next. Which is why,
with the problems, the phone companies went to the gas-filled type of protectors which don't have all these attendant problems.
Gas-filled units also became available for this type of protector as well. Though this one has the carbon and porcelain
blocks, if gas unit had been installed, they also would have painted white to differentiate between the two.
The picture immediately above is an example of a gas-filled protector.
In the area in which I worked for the phone company, these originally came out in black and later in the blue color seen here.
There is no significance to the color. The units perform the same. The two outer binding posts can be used for
attaching both the drop wire and the inside wire (IW). Usually, however, only the drop is attached as will be seen in
subsequent photos. The network interface (NI) module is attached to the binding posts via spade-clipped wiring
(colored green on the left and red on the right) as shown here. In this example, only the module wiring is attached
to the factory pre-equipped NI. Other photos below show the protector with drop wires attached. Not all NIs are
factory-equipped with the maximum number of protectors and IW modules which the unit can accommodate. The center brass
strap is used to attach the protector to the NI by way of the ground lug.
NIs come in different sizes and shapes but these below are representative of what
you should find for your premises.
Before we move on to the Network Interface, there is another type of
protector which you may find on your premises and that is the multi-pair protector, usually referred to as a "six pair can."
Below is a picture of one which has been opened.
In the picture above we see twelve binding posts for the termination
of drop wires and, at either end of the block, two ground lugs, or binding posts, which have larger securing nuts for the
ground wires.
You'll notice what looks like grafitti on the inside of the open cover. These
were drawn by the telephone company technician to indicate the paired binding posts for the various wire runs inside this
terminal or protector unit and denoting the various circuit or lines which are working in this protector.
At the top of the block are screws with caps either of natural brass or painted white.
These are the actual protection units. The difference is that those which are white are of the newer gas type whereas
the ones which are brass are the older carbon and porcelain block type.
The carbon and porcelain blocks in this protector are prone to the same noise problems
as rectangular type mentioned earlier. The gas type are not.
The picture below gives you a better look at the protector units, service binding
posts and ground posts. In this you can a bit more easily see that the drop wire and the Inside Wire (IW) are both terminated
on the service binding posts (drop wires are thicker, IW, thinner) unlike in a Network Interface where the drop wire only
is terminated on the protector binding post and the IW is terminated on the binding posts in the customer module.
The thick black wire coming down and around the right side of the can and into the
grommet in its lower left corner, in the picture above, is the drop wire containing six pairs. Buried drops coming
into a terminal such as this will only have five pairs.
More on NIs
The network interfaces in the two pictures above and the first one on
this page are all a little bit different.
The second, or lower, of the two immediately above is same
size as the one in the first picture on this page.
The first one, or upper, of the two immediately above is larger
than either of the other two.
All of these network interfaces can accommodate up to six lines.
Some interfaces are pre-equipped for all six positions, some for just two and others only come from the factory setup for
one line. It all depends on what the local phone company ordered. But telephone company technicians should be carrying
extra protectors, ground busses and IW modules to finish equipping the NIs for the number of lines to be installed.
The pictures above and below are of the inside of the two interfaces
just discussed. You will note the difference in the layout of the equipment. Normally, the customer can only access
the IW modules as it takes a special wrench (Allen type design with a hole drilled in the center) to open the entire
interface. (See the third picture below of what the customer would normally see with the door to the customer
side of the NI opened.)
In the picture immediately above you will notice on the left side that
nothing appears there which looks like the gas-filled protectors we discussed earlier. The small device shown is the
very latest type now being used in the industry. It is less than half the size of the blue protectors shown above, but,
it performs in the same manner. Again, both the drop wire and the IW module wires are both attached to the protector.
Also in this particular example, we see that the phone company came out and installed
a network interface by cutting into the existing drop wires which originally went into the basement of the home. The
company ran a new drop from the telephone pole to the NI (the multi-pair wire on the left - color coding blue-white, orange-white)
and then they routed the old drop wire to the customer side of the interface so they wouldn't have to run a new piece of IW
into the basement. This is a common practice so you could expect to find drop wire on the customer side of the interface.
Additionally, when the company does this, they like to cut the ground off the protector in the basement. That's so as
to eliminate a line outage or line noise should high voltage hit during a storm, or some such thing, and cause the protection
units in the old protector activate.
Any time you find drop wire on the customer side of the NI there's undoubtedly an
old protector inside somewhere.
Sorry for the quality of the picture below as I just zoomed in on the
original. But this is a close-up of the latest type of protector unit, which has come into service, showing how the
drop wire and IW module wiring is attached.
In the picture above, only the customer wiring side of the Interface
is open. This interface originally came wired with only one IW module and a second line was added later. This
explains why there is a black neoprene boot over the IW binding posts of the lower module and none on the upper.
The boot was later done away with as being unnecessary if the interface is properly closed against inclement weather or anything
else.
The early modules not only had the boot but they also had four termination
screws rather than the two shown on the module above it. The ones in the lower module were painted the standard four
colors of red, green, black and yellow. Only the red and green were connected by spade-clipped leads to the lightning
protector. The yellow and black screws went nowhere and were some times used as bridge points for multiple line and
IW applications.
Now that we've covered Network Interfaces and Lightning Protectors,
we finally come to the reason for this particular page.
All too often, many buildings have multiple Inside Wire runs being fed into and terminated
on the IW modules of the network interface. A recent conversion I did had eight of these wire runs pig-tailed and closed
down on the IW module. The problem with this is that it can be very difficult to make changes in premises service if
multiple lines are in use or additional jack locations need to be added.
Maintaining good wire connections becomes difficult because virtually every time
the screws are tightened on the wiring, it is crimped or otherwise damaged which weakens the wire at the screw and can lead
to failure by the wire just being moved inside the interface thereby causing a failure in service to one or more jack locations,
or, even possibly short out the two sides of the line knocking out service altogether.
The solution to this problem is relatively simple, but, putting it into effect can
be somewhat of a problem. A problem because you can't just walk into a store and pick up the equipment you need to rectify
it. Well, actually, you can. I just meant that there is nothing of which I'm aware made by the industry for this
application. Everything is virtually a jury-rig.
So, in the next series of pictures, is a solution I've been able to implement.
Commentary will be below each picture.
This picture is of the same interface as is shown in the first picture
on this page. What you're seeing now is the finished arrangement. I'm sorry now that I didn't take pictures before
I made the changes. I added the box on the left and moved the considerable amount of wiring you see going into it from
the customer side of the network interface. The wiring originally came out of the crawl-space, went to the right following
a ring-route and into the interface. In this final arrangement, there is only one wire run from the NI to the new
box which now accommodates all of the IW on a permanent basis.
With both devices open you can clearly see the new wiring arrangement
- the single, 4 pair, cat 5 IW between the NI and the bridge block is the feed from the Network Interface and brings the service
to the new terminal I created.
All the wiring from the house is now permanently wired to the block of
the terminal and never has to be moved again. Yet, access is had to all pairs of each wire run.
Regarding the smaller block to the right, I brought the 4 pair wire cross connection
from the NI to the last four pairs of this block. This terminal can now accommodate up to four lines, dial-up or DSL.
The cross connect wire is terminated on the right side of the block and also never has to be moved again.
Both of these blocks are split down the middle. The right side of the block
is independent of the left side.
To bring the lines to the required IW pairs, a wiring cross connection is made from
the left side of the smaller block and looped through to the various IW pairs where the line is needed on the premises.
In this case, there are two lines coming into this terminal. The second line
is being used for Internet access and is only going to one jack location on the premises. To get the service from one
side of the terminal blocks to the other, a device called a "bridge clip" is used - to bridge the gap. Those are the
red devices seen in the picture.
The uppermost location of the block on the left is the wire run for the room where
the computer which accesses the Internet. There are two bridge clips in this location because the house line goes to
the first pair and the line for the computer goes to the second. In the house is a dual port jack; each jack is wired
for one line - one for the house line, the other for the Internet.
The jack location just mentioned can also accommodate two additional
lines should it be necessary if used for, say, a home office or the like.
You'll notice at the bottom of the block is a yellow wire which is wrapped up and
stored. It is from the pink wire run shown coming through the box grommet. This was the original wire run put
in the house after it was built about 45 years ago. At that time, two-party lines were still much in use. And
while the house only had one line and therefore only need one pair of wires, the IW needed a ground lead for the bell circuit
of the phone if the owner had two-party service. As that is no longer the case, the yellow lead is not needed and is
stored. You cannot get service over only one wire and the yellow lead now would only be used if one of the other leads
became damaged. It could then be substituted for it and service restored.
Now that I've covered everything I can think of at the moment, I've offered
this as a solution to a wiring problem if you need one.
The box I used was a Rubbermaid, 1 1/2 gallon size capacity. The dimensions
are 4 1/2 inches by 7 1/2 inches by 14 inches (actually 4.5 X 7.6 X 13.9 but what I gave you is close enough). The box
is clear with metal flecks. I went to Ace Hardware and bought a can of their Premium Enamel, interior/exterior
Sage green spray paint and painted the inside of the box and cover leaving the back of the box clear (so I could judge where
to drill the holes to mount it to the brick wall).
The blocks I purchased from Graybar Electric and should be available from any store
which sells electrical and communications gear. In particular these blocks are --
Left block - Siemon's (manufacturer) Model S66M1-50 (50 pair split block, 25 pair
with bridge clips) mounted on a Siemon's S89B bracket; the type of block is called a 66 block.
Right block - Siemon's Model S66M4-25 (four pins across for a total of 25 pairs on
the block - 12 1/2 pair if used with bridge clips) mounted on a Siemon's S89E bracket.
The bridge clips I used were also made by Siemon's. This was the brand carried
by Graybar in my area and it is good equipment. In your area, the electrical supply houses may carry different brands
but they should all work well regardless of brand.
What these pictures didn't show however is that there are covers available for these
blocks as well if you want an extra level of protection. I didn't think it was necessary because the Rubbermaid cover
snapped so well into place to seal it from the elements. But, in this case, more is not going to hurt anything.
It's up to you.
Well, that just about covers it. This solution is similar to the
section of this website listed in the Navigation Bar on the left as "Have a Wiring Nightmare," except this is for outdoor problems. If you have any questions, please feel free to contact me. The easiest
way is by email because I don't always get phone calls in my household.
Good luck.
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