On July 25, 2014 at 12:43, Craig Aguiar-Winter said...
Hello everyone.
A client I've done a lot of work for has four cameras installed (came with the house). Their cables are fed to a location beside the electrical panel and I want to extend the cables about 20ft each to a rack I installed in a utility room.
The first thing to consider is that twenty feet is not a lot of distance.
The cable in question is a RG59 Siamese cable.
So you're dealing with plain old composite video plus power for the camera.
I. In the past I would have just attached whatever coax I had on hand but I have been reading the A/V Installer's Pocket Cable Guide (maybe not the exact title) as recommended by Ernie, and if there is one thing I have leaned it's that there is way more to choosing a cable than I previously knew.
Keep in mind, though, that this is the Installers Pocket Cable Guide, not the Extenders Pocket Cable Guide... okay, that's a bit of a joke. What I mean is that it goes quite deeply into what cable to choose to be the best for each situation. The longer you do this work, though, the more you'll find that reality is not quite as stringent as theory, except with digital signals, and you can read about the digital cliff in that book.
In an effort to do the best job I can, I ask what kind of cable should I extend these cameras with?
Best practice: The same cable.
I asked one of my suppliers if I can just use the RG6 cable that I have (quad shield with copper clad steel conductor) and he said no it won't work.
He's wrong. Here's what it is about "the same cable" that makes it appropriate: it's the same impedance and has the same shielding properties. RG6 and RG59 are both 75 ohm cables, so they will handle the video signal almost the same way. The difference is that the steel core of the CCS offers higher resistance to low frequencies, so it's not right for camera signals. Not right, I said? But wait -- it's only twenty feet! Because it's such a short distance and you're passing an analog signal, you should be just fine with RG6, even copper core.
If you notice that I'm going back and forth between saying yes, it's okay, and no, it's not, you're right. The book defines best practice, but there's a lot you can get away with if you have to. So... do you have to use RG6 because you don't have ANY RG59 and don't want to buy a thousand feet of it to make four twenty foot extensions?
Is that what's bothering you, Bunkie? (intermission now: )*
I asked why, he said the larger center conductor in RG6 makes it incompatible.
This is a person who does not understand the implications of the things he knows. Yes, it's larger, but it's 75 ohms. If he understood, he'd talk about the steel core.
My first instinct was that's a load of crap but then I realized I actually don't know if he's wrong.
It's not a huge load of crap, though!
He didn't give me enough of information to back up his statement though so I'm still inclined to think he has no idea what he's talking about.
He doesn't have enough information etc etc.
Unfortunately I don't have any specs on the cameras.
First, any camera for which RG59 siamese cable has been run can use RG59 siamese cable. Analog video is a 75 ohm signal.
Without that can someone tell me what the typical cable used for this application is or can use my RG6 quad and separate power wires to make the extension? I don't plan to get into security so I don't want buy 500 or 1000 ft of cable just for this one job. But if I need to I will.
Gee, just what I guessed.
If you use RG6 and zip cord, your signal will be fine but your installation will look like a complete effing amateur did it. The results for your client will be okay, but if anyone with an ounce of A/V sense (or not, like the client's kids, who know audio/video because they are investment bankers) comes along and looks at it, they will say, "gee, what the hell happened here? Didn't this guy know what he was doing?" I know I would!
So the reason to use RG59 in this case is to maintain your image, both on the monitors and personally, in your client's eyes. I don't know where one can buy siamese by the foot, but I think you can get RG59 by the foot from Home Depot! If not, you can get a hundred foot long cable from some online supplier, cut it to length and install BNCs. If you haven't installed BNCs before, drop me a PM here.
That's another thing -- if you use RG6, it will be more difficult to find BNCs for it than for RG59. You'll use F connectors, then somewhere an adaptor to BNC. And RG6 is stiffer than RG59, so it will be harder to connect to the back of the DVR. Based on my most recent experience with RG59, for that reason alone you don't want to use RG6. EDIT for clarity: Once more recently I experienced how difficult it is to connect a bunch of BNCs on RG59 to the connectors on the back of a DVR, which are really close together; I'd hate to have to do that with RG6 plus the needed F to BNC adaptor.
I'm sure Home Depot has some 18 ga two conductor or four conductor wire that you can buy by the foot and hook up to extend the power part of your camera wiring. You just don't want it to look like lamp cord.
Thanks, Craig.
You're welcome, Ernie
edit: *The Old Philosopher, just one of those things that people who were around in the sixties might have heard once or twice and the name of whom they cannot, for the life of them, think of.
Last edited by Ernie Gilman on July 25, 2014 17:28.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
