What amp power supply for "DC12V±10% 500mA" item?

[jobss]

I've got a cctv camera with the following power supply spec: DC12V±10% 500mA.

I'm trying to understand what this means since I have 4 of the above cameras and I'd like to use a 4 way DC power splitter to save space. I'm not sure which 12V DC power supply I should buy as they come in 1-5amps.

Can you help me understand how amps relates to this and which power supply would be suitable?

Thanks!

 

[ubercake]

Those cameras require less power than 1Amp a piece as the are listed at 500 milliAmps. If you could split 2Amps 4 ways somehow, this would do the trick. I don't recommend doing this with some universal power supply though.

 

[molletts]

As Ubercake said, they use less than an amp each (500mA = 0.5A, i.e. half an amp) so you could get away with a 2A PSU.

If you're planning to have some or all of them some distance away from the shared power supply, though, you'll have to be quite careful about the voltage drop in the cables. If you just use thin low-current wire, you may find that the voltage is too low by the time you reach the camera end. You might be OK with 3-5A rated wire, depending on the distance. This, of course, wouldn't be an issue if the cameras were powered "locally", with individual power supplies near each one, which is how I imagine the manufacturer intends them to be powered.

One alternative to get around this might be to use Power over Ethernet equipment and deliver the power over Cat5 cable, even if they're not Ethernet cameras. A small PoE switch with 4 powered ports could act as the shared power supply and you could use something like a TP-Link TL-POE10R PoE splitter at each camera to extract the power and convert it to a regulated 12V supply. Voltage drop won't be an issue because 1) PoE uses a much higher voltage (and therefore a lower current) and 2) the splitter will compensate for any small drop that does occur when it converts the voltage down to 12V.