we are doing a project with many long cctv runs ,
the longest - up to 300 ft? maybe 250?

we are home running them all to a central location,
we were thinking that maybe we should run the power to closer centralized locations . .

is it an issue if the power is of different distance then the video?

all the cameras would be home run to a closet,
then we would have 4 different power home run closets
so they have enough power . .

does that make sense?

Power from a different location could cause ground loops. 300 Feet should not be that big of a problem if the camera is powered via AC. If you are doing a DC camera then you should take voltage drop into consideration. So DC would not be as good of an idea as doing AC. I have personally done several Grocery stores with cameras all over the store using longer than 300 foot runs and as long as you use an AC camera you should be fine.

RG59U limit is 750'. Power will be the only issue, but with 18/2 and any current cameras on the market - non issue.

We use Siamese RG59 and 18/2 for CCTV.  Have plenty of runs at 300' never had an issue. 

If you are running separate power wire I would go with at least 18/2 and you'll be fine.

It's not an issue if the power is different distance than video.

Like you said, I would just home run them and everything will be fine.

Look at your mapping where cameras to be installed; devide them in groups. Install a power supply for each camera group.

Run RG-59 siameses from camera to power supplies; then splice RG-59 (siamese) at power supplies and run plain RG-59 to central closet location.

Yeah, yeah... You ended up using twice the number of BNC connectors and additional of F to F BNC barrels. Rather have a little video level drop than to deal with voltage drop. Sometimes, not able to power cameras at all.

love it . .thanks guys!

going with the indigo plan.
makes perfect sense.

that way if we ever have an issue in the future
we can do local dvr's if needed since we will have
access to them on each floor via the splices.

Run a CAT5 or several to each cluster, use video baluns and local 24v Altronix power supplies.

This is a good solution if you use Cat5 all the way from head-end to camera because it provides a ready-made upgrade path to IP cameras. The cable is cheaper, too.

Ignorant question: I've seen that AC cameras sync nicely because they are all tied to the power line. How do DC cameras sync so there's no loss of sync when switching from one camera to another?

I think sync and line lock stopped being an issue when DVRs became standard. Back in the olden days of sequencing switchers and multiplexers it mattered. I also find that cams work much better on 24VAC rather than DC when you have a choice.
Siamese is expensive, so are baluns but if the run is any kind of distance we almost always run CAT5. Cams are like drugs, when people get hooked they always want more and when you have a couple of extra pairs waiting they are easy to add.

I just dug this one up and have a question. My longest run is 300 feet and I'm using 24V cameras. Is there going to be much signal degradation at this distance using RG59 - 21 guage?

ac or dc?

ac

[Link: lmgtfy.com]

That's a handy calculator...Thanks