Perhaps I have misunderstood your answer, but the problem is that the
wire comes in from above -- i.e my concern is the "drop" from where
the line reaches my house at about 15 ft off the ground and then drops
to the level of the basement. My question is about hardening this run
by encasing it in conduit.
Remounting the network interface device internally won't help because
an exposed wire still runs down the side of the house.
firstname.lastname@example.org (Jeffrey J. Kosowsky) writes:
]> Depending upon where the inside hydro panel is located, it might be best to ]> dig down about two feet underground and drill through the basement wall, and ]> remount everything inside the house. Although this can cause some ]> inconvenience later when the telco has to visit to repair the local loop ]> from the GWI to the house, it's nothing compared to the "inconvenience" of ]> being broken into and having the monitoring non functional......]> ]> R.H.Campbell]> Home Security Metal Products]> Ottawa, Ontario, Canada]> www.homemetal.com]>
]Perhaps I have misunderstood your answer, but the problem is that the
]wire comes in from above -- i.e my concern is the "drop" from where
]the line reaches my house at about 15 ft off the ground and then drops
]to the level of the basement. My question is about hardening this run
]by encasing it in conduit.
]Remounting the network interface device internally won't help because
]an exposed wire still runs down the side of the house.
Well, you could have the line go into the house right at the strain relief
attachment to the house. However, the perp with a long pole tree trimmer
could probably still cut it. A cell phone hookup is another possibility,
until they come in with a jammer.
This subject comes up from time to time. The following is culled from
earlier posts I made in reply to similar questions.
You can "harden" the line by enclosing it in galvanized, threaded pipe from
a point that is difficult to reach if it's an aerial drop or from a cement
pad if it's an "underground aerial" (strange, but that's what many telco's
a buried drop). The DIYer (or technician) can install some means of backup
such as a cellular or control channel transmitter or even long range radio.
Another possibility (one which is significantly less expensive) is to harden
the phone line. This is done either by moving the incoming line and the
telco "demarc" (gray box on the side of the house) inside or protecting it
with a heavy metal enclosure. C&C Products makes a fairly secure, tampered
enclosure called VoiceLok for this purpose. Here's a link (my website) to
I have a friend who remodeled and moved the telco demarc inside his garage,
leaving the old one sitting outside (unprotected, as you noted). A few
months later his phone went out, and he called the telephone company for
repair. The telco tech showed up and worked outside for a while, then
finally came to the door and asked "how long has your telephone been out of
service?". The tech had been testing the circuit up to the old
demarc...never thinking that the circuit might have been moved inside.
If it is good enough to fool Bell South, it should be good enough to fool
My understanding is that, if your alarm system is actually monitored,
then cutting the line will cause the alarm co. to react as if the alarm
had gone off, so hardening it is pointless. Is there some reason why
you don't trust the alarm company to answer these questions?
Sir, if you are using a conventional telephone line for monitoring, that is
NOT the case. Your alarm panel is a passive device, only using the phone
line when it needs to send test signals, alarms or other signals such as
openings and closings. Cutting the phone line doesn't send anything to the
central station because there is no phone line to do so.
Your alarm can be programmed to actually trigger the alarm in the event of
loss of dial tone, but this is nothing but a "local" alarm. The central
station doesn't know your alarm may not be working until the panel fails to
send in its programmed daily or weekly test signal. If you are using some
means of wireless backup, then the above doesn't apply, and your CS could
well know of a line cut.
So hardening the phone lines CAN be a measure of additional security worth
doing depending upon your particular situation...
Home Security Metal Products
Ottawa, Ontario, Canada
Unfortunately, that is not the case with any but a very few high end systems
for banks and such. Residential alarms are typically monitored using the
switched telephone network. In somple terms, the alarm makes a phone call
to the central monitoring station's alarm receiver. If the line is cut no
call is made and the alarm company does not know it.
Many years ago it was common to build systems with "line security." A
dedicated copper pair was connected from the protected premises, through the
telephone company central office to the alarm central station. A voltage
was applied to the cable. Two different resistors were wired between the
circuit and earth ground. Shorting one resistor meant burglary or holdup.
Shorting the other meant fire. A line cut showed as a trouble condition.
In another ancient system a loop of cable was connected from the alarm
company, through the C.O. and then through an alarm Mc Cullough (I forget
how it was spelled) transmitter at each protected premises. Upon alarm a
motorized cam wheel would close and open a switch, creating a series of
interruptions in current on the loop. At the alarm company office this was
translated into a series of marks or holes in a tape designating the account
number. A clerk then looked up the account called the local authorities.
If the line was cut an alarm company agent would be dispatched to
investigate. The problem is these loops were long and many properties were
often connected to each loop. It could take many hours just to find which
property has a fault.
Another problem with leased line security is most telco's don't want to
provide the dedicated copper pairs any more. They can make far more
profitable use of that single pair as part of the dial-up system. Finally,
new outside plant lines are gradually switching over to fiber optic which
does not support inexpensive line security devices.
No offense, but the primary purpose of this newsgroup is to provide a place
where people can share information on alarms. The gentleman's query is
on-topic and appropriate.
]Another problem with leased line security is most telco's don't want to
]provide the dedicated copper pairs any more. They can make far more
]profitable use of that single pair as part of the dial-up system. Finally,
]new outside plant lines are gradually switching over to fiber optic which
]does not support inexpensive line security devices.
Except that now they can actually use that copper pair for far far higher
data transmission rates-- eg ADSL modems, etc. Thus one could imagine
putting an ADSL type signal on the line to the phone company-- or if the
user uses ADSL via the user's ISP-- and monitoring that for disruption.
Most homes have two lines (ie two sets of twisted pair) coming in anyway
On Mon, 15 Nov 2004 19:49:22 GMT, email@example.com (Jeffrey
J. Kosowsky) wrote:
Generally threaded iron pipe is used, though normal EMT conduit should
be okay. Most monitored systems respond in the phone line is dead,
and an external alarm bell can be used as well. The best is a
cell/radio backup of course.
That's easy. Disguise your NID by relocating it or burrying it in a
dry spot. Now setup a dummy NID with a very obvious phone line wire
going to it. Wire that dummy phone line to a zone on your alarm.
Burglar cuts what he thinks is a phone line and the alarm goes off.
Cheaper than radio or cellphone backup.
(An alternative is to wire the dummy phone line to 220V so the burglar
gets dead if he cuts it. Just make sure it's not a lineman for the
firstname.lastname@example.org (Jeffrey J. Kosowsky) wrote in message
email@example.com (davefr) writes:
]That's easy. Disguise your NID by relocating it or burrying it in a
]dry spot. Now setup a dummy NID with a very obvious phone line wire
]going to it. Wire that dummy phone line to a zone on your alarm.
As has been said often, in many places phone lines are above ground and run
to telephone or hydro poles. Ie, a dummy is very very easy to see-- it does
not run up the telephone pole. And the line is outside and possible to get
at. The run down the house is hideable-- eg inside the walls (although the
telco is going to be loath to do that-- the line is continuous from the
pole to inside the house usually.
And if an attacker really wants to they could use a tree trimmer with a
long pole to just cut the line, even if it is 15 ft above ground.
]Burglar cuts what he thinks is a phone line and the alarm goes off.
]Cheaper than radio or cellphone backup.
Burglar follows line from telephone pole to house and knows which it the
](An alternative is to wire the dummy phone line to 220V so the burglar
]gets dead if he cuts it. Just make sure it's not a lineman for the
And you get charged with premeditatied murder.
] firstname.lastname@example.org (Jeffrey J. Kosowsky) wrote in message
]> We are installing a centrally monitored, wired alarm system in our]> house.]> ]> I noticed that the Network Interface device sits unprotected at waist]> level on the outside of the house. Even more concerning, the phone]> line enters and exits the box unprotected.]> ]> Other than paying for a radio link backup, what is the best way to]> "harden" the phone line?]> ]> - Would it make sense to encase it in electrical conduit at least]> until the wire is out of reach?]> ]> - If so, What type of conduit and fittings should one use so that it]> is both sufficiently tamper-proof and weather resistant?]> ]> - Any other suggestions?
Put a couple resistors in the circuit. Still 220 VAC, but not enough current
to do real damage. Might be a good idea to hook it up to something, say a
small lamp or garden soil heater, or whatever. There..it's not to kill the
idiot, it's to keep the seedlings comfy. :-)
If you are protecting the phone wire you would do better to run it with UF
cable so it LOOKS like a power line.
Chances are a person cutting a phone wire with power in it would only make some
sparks and trip the breaker anyway.
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