I got to thinking today. Everyone hates wall warts, they are ugly & take up so much space. Then I was looking at a customers DIY Rachio sprinkler system install. He did a clean job on the sprinkler wires & dished then through the wall but again, the ugly wall wary and power cable was dangling there. Then I said to myself, why don’t I start pre wiring for a low volt power cable for sprinklers & everything else? Would look so much cleaner. Then I was thinking, well I’m not even sure you can do that haha, but cameras and alarm panels etc can work, so how long can you actually run? I know it depends on wire awg. But let’s just say 16-2?

Somewhere between you rack and the moon?

Or you can use a voltage drop calculator and figure it out:

[Link: calculator.net]

I figured, thanks though.

How long? Why, for months and months!

So you can figure the voltage drop. How do you know how much voltage drop is a problem? If something says it's supposed to be powered with 12 volts, is 11.95 ok? Must the voltage be higher than 10 volts to work? I don't know of any equipment that specifies the lowest usable DC voltage.

I've thought of providing 12 volts for various little lights in different places in the house. I'd have to install a system similar to a 120 volt AC system though smaller wire would be acceptable. 16-2 is a good start. It would be smart to use the connectors used on most CCTV cameras, too, because LOTS of 12V products use those connectors.

Do you have a specific product in mind that you would use this for, or is this for more of a catch all low-voltage in general type sollution?

I ask because if it's one specific I product, perhaps you could either get a variable power supply, hook up what you are using and drop the voltage until it doesn't work properly, or try for go/no go type wire length. Hook up 200ft of 16-2 and see if it works. If not, try 150. Etc. HEOS speakers might be good to try this wth.

This is getting ahead of things a little, but If you were to run LV from a central rack type location, I would recommend fusing each run based on what that specific wire would be rated for (or less), as far as current capacity, since one large power supply could potentially supply enough current to heat up a single wire that shorted. It would also allow you to pull fuses to reset individual products and trouble shoot.

Craig.

How do we fight voltage drop for security cameras? We use an AC power supply and cameras that can use it but for the few times we need a camera that can't, we use a converter to change to DC. What voltage do you need? How much current is involved?

That's why some cameras are 12v dc, others are AC, different power drop.

No such thing as power drop.

Being AC or DC would have no effect on voltage drop at all.

Voltage drop is purely a function of current flow and the resistance through which it is flowing.

Well, different application- one is fine for shorter distances (based on current) and the other will work for either long or short runs. Voltage drop causes all kinds of problems.

Suspect the standard that one day will come will be POE.

And vendors will build their equipment based on that, with an internal transformer to drop down to their needs. And for those that aren't using a central hub, then a 48v supply will become as ambiguous as today's 12v.

Then we'll have POE switches with ports without ethernet for dumb devices, and/or dedicated supply hubs designed in the style of switches.

For now, their are some POE voltage down converters out there. Most going down to 12v or 5v for things like NEST.

POE to USB C example:
[Link: amazon.com]

I always test voltage with almost any connection, no matter what the lenghth., if I can. Any time I do a splice. Call me ultra-paranoid, but I've had faulty wires cause much undo stress in major installations. better safe than sorry.
Redmond Home Theater

auralenhancer,
what do you mean by "test the voltage"? and "if I can"?

I've seen people here stymied by low voltage at a camera, after they say "I measured the voltage at the end of the 200 foot wire run and it was spot on."

A voltage at the end of a long run won't tell you what the voltage is when a camera is connected. There are no standard connectors or Y cables for wiring up power to check the voltage -- you have to make your own if you intend to check this. That's why I ask what you mean by test the voltage.

What are the conditions where you can't measure the voltage?

Voltage should be tested while the circuit is "under load" (operating).

Just use the calculator. Punch in the numbers from power supply max output figures that came with the device. Example 12v 1 amp and you want the same at 300 ft. Let the calculator provide the wire size. 12/2 should do it. Keeps you from hoping the voltage you feel is high enough at the end of 16/2 is enough

Wow, there's a lot to say. Sorry.

capn, "just use the calculator" will work if we can somehow find out the actual amount of tolerable voltage drop.

"The same" means no voltage drop. "No voltage drop" requires zero resistance, which is impossible. But let's figure out what will happen with your example, using 12/2. In practice, 12/2 seems ridiculously thick for camera power, but the numbers might surprise us.

12/2's resistance is 1.588 ohms per thousand feet. 300 feet has a resistance of 0.529 ohms. There's a hot lead and a ground lead, so resistance is twice that, or 1.059 ohms. At one ampere, the voltage drop is 1.059 volts, so the delivered voltage is 10.941 volts.

We now have the question, will the camera work properly with 10.941 volts? Have you ever seen a "minimum applied power" voltage specification? And we're still making the assumption that the connection points will have zero resistance. (Just for reference, a 300 foot run of 16/2 would deliver 9.59 volts.)


You've still got hoping and feeling in there, instead of knowing and measuring. I'll bet no camera manufacturer specifies the ACTUAL lowest operating voltage of its products, so guessing and hoping are still part of the situation.

The worst situation as an installer would be replacing a non-IR camera at the end of a long run with a camera that has IRs.. It could work fine during the day, but when the sun goes down and the LEDs attempt to turn on, the voltage drop could be too much. The camera could switch on and off repeatedly, or reach some stasis where it's not quite on. I'm not sure.