question on security cam: Running 12v on Cat 5?

  • Thread starter Thread starter Tommi Bauer
  • Start date Start date
Hmm, dunno about CAT5, but the original (was that 20 gauge?) phone wiring
was supposed to be able to carry enough current for a solenoid ringer. I'm
pretty sure that's more than a few milliamps. I would guess at least 10s
of mA, maybe even up to 100 mA? but AC in bursts (allowing cooling?).
Those black phone ringers can be LOUD!
I don't disagree about the limited current capacity of CAT5 (24 gauge)
cable. However, many newer cameras draw very little power. Some are
designed specifically to run power and video over CAT5.
Click to expand...

I'm too lazy to find my wire tables to check current capacity. I would
still think it's good for some 10s of mA, at least. This cable must be
good enough to provide power (48VDC) for the electronic phones that are
plugged in, with all their fancy features, even though ringing current
required for electronics (piezo speakers) is not that high anymore.

If you can supply electrical power for a fancy phone, you should be able
to get enough for a small camera, perhaps optimized for low power?
Other cameras can be made to work with category cable by using baluns at
each end. As with any type of processing there is a certain amount of
distortion and noise introduction in a balun. How much is an inverse
function of quality. If you use good quality equipment you will not have
noticeable loss.
Click to expand...

Yes, I'd say. If CAT5 is good enough for 100Mbps ethernet, in both
directions, there must be a way to get a reasonable signal through. As you
suggest, you might have to go "balanced" via the balun. The other approach
is to "go digital" right away, maybe even compressed? Nah, that probably
requires more CPU, hence more electrical power, etc.

BTW, make sure you use wires that are "pairs" for your balanced pairs,
don't just grab any 2 wires in the bundle. The pairs are twisted along
their length within the CAT5. If you use wires from 2 different pairs, you
would be coupling more interference. You (all) probably knew that already.
 
Forgetting Network and IPs, it is used in the CCTV industry alot with
Baluns, Active and PAssive Hubs for real time high quality (near
fiber) up to 1.5 miles. See www.NVT.com for further info.

Rory
 
Jerry said:
CAT5 wire was not designed to run devices that require more than a few
milliamps. Also, if you are going to put video over this type of wire that
is not in digital format designed for CAT5, the pictures will be severely
degraded.
Click to expand...

Um, CAT5 wire is simply 24awg wire.
In metal.

It's twisted pair. I stood in a Wall St control room where they used
CAT-3 wire to send THOUSANDS of video signals down to monitors on a
trading floor 5 floors below. Bundles a wire as big as a fat mans
thigh running down carrying composite video to green screens.

So lesser wire running lots of video with lots of other signals running
with it.


Power? Sorry, running wireless access points at 48VDC and 16VDC
(1/2 amp on that last). Maybe 80' of wire.
If your camera is putting out baseband video, or RF video, you will require
the proper specified wire for the video. As for the power for the camera,
the proper type wire will also be required.
Click to expand...


or not.

You're clearly not posting from experience.
 
Category cables can also handle DC with ease: one of the mainstream
manufacturers has guidelines for using it with DC where they confirm CAT5E
can be used in a 24V circuit with currents up to 1A per a pair or 3.3A
combined total load for all four pairs.

It is also routinely used for Power-over-Ethernet (IEEE 802.3af) devices
that draw up to 350mA @ 48V (15 to 16 Watt)

Therefore, powering a camera through a category cable does not create any
problem.

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------
Jerry G. wrote:



The phone ring is in the very low milliamps of current. It is also not
DC.
Click to expand...




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quartic said:
while it may have some tiny effect on audio or video quality (may have
none), it shouldn't be a problem to run the power and signal in the same
cable, if your video can indeed be piped across a cat5. Communications cable
is described as "power-limited", which means it can only be used on circuits
of 50 volts or less with limited load current. Since your device operates at
12 volts, and very low current, and cat5 is rated as a power limited circuit
cable, then it is well within the design specications of the cable to carry
power.
Click to expand...


And with VERY HIGH END - like $2000 (and lesser) - microphones, we run
power on the audio wires. Audio is AC. 48VDC is, er, DC.

DC doesn't pass through capacitors or transformers.

It doesn't affect audio (20KHz) at all. At the much higher frequencies,
it would also be moot. (presuming your camera is expecting it).
 
while it may have some tiny effect on audio or video quality (may have
none), it shouldn't be a problem to run the power and signal in the same
cable, if your video can indeed be piped across a cat5. Communications cable
is described as "power-limited", which means it can only be used on circuits
of 50 volts or less with limited load current. Since your device operates at
12 volts, and very low current, and cat5 is rated as a power limited circuit
cable, then it is well within the design specications of the cable to carry
power.

cm^4
 
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