First post!
My question is straightforward, and NOT a duplicate post. This is meat & potatoes here, less on theory, more on practical application. I know you are all more knowledgeable than I am. Hoping for a quick answer (which doesn't theorize about Johnny or his appetite for apples).
I'm thinking of buying a non-PC power supply to do some stuff with LED light strips. I have read some about series and parallel connection options. I'm good as far as that goes. I can follow pictures/procedures. Here's what I have NOT found an answer to searching all across the web. My project might involve other devices and so my question is:
The power supply is 600W 12V 50A. This will exceed my total need. The question has to do with the number of terminals on the power supply itself. Here's a picture of it:
You'll notice it has 3 terminals +/- on the back.
At long last, my question: WHAT IF I HAVE MORE THAN THREE DEVICES?
As long as each and every device is rated for 12V (USA) and the total will not exceed maybe 400-450 watts tops (honestly, not sure how many amps will flow, but definitely under 50), can I rig up more than one device on each of the 3 terminals?
In my mind, I'm thinking I could strip wires and then just stack them on top of one another, considering and then deliberately choosing which terminal to use to try to "balance the load" <— used here in a logistical sense, not just in terms of numbers of devices to be connected, but also in terms of "equal" power supply per terminal.
Essentially, I want to eliminate wall warts and power bricks. Simple. One plug in the wall, grounded, for everything. Can I do it?
Assuming ALL the components/devices are 12V, don't add up to 600W and won't push anywhere near 50 amps?
Let's say I have 7 or 8 devices, not necessarily just LED light strips. Can I do it? That's all I want to know. Additionally, does it help to try to evenly distribute the total across just 3 terminals?
If I CAN'T do it, can anyone tell me how to achieve my desired result? I've already considered the potential downsides if the power supply fails/cuts out or alternately decides to fry everything. To me, it's worth the risk.
I want to eliminate wall warts. I may buy a power supply so I can hook all sorts of stuff into it. Gentlemen, how should I proceed? No theory; just practice, please. I'm looking for confirmation, yes or no, that I can do what I want. If not, a pointer in the right direction, and thanks for reading my long-winded question!
Best Answer
The only reason there are three pairs of screw terminals is due to the high amperage output of the power supply. If you were to try to carry 50 amps over a single wire, it would need to be very large diameter and you would not be able to safely connect to a single screw terminal of the size used. If you check with an ohmmeter, with the power off, you will discover that all three V+ terminals are connected together internally (same with the V-).
If you wanted to have a single load taking all 50 amps, you could connect it with three pairs of wires, each large enough for at least 16.7 amps.
Similarly, if you had many loads to share the amperage, totally less than or equal to 50 amps, you could connect many wires to the terminals. If you have only a few pairs, you could connect them directly to the screw terminals. If you have more, you could run few large wires from the power supply to a distribution assembly to branch out to all of your loads. This could be terminal strips, buss bars or even a PCB. Take a look at the answer from @xakepp35 for ideas. (I believe it was downvoted because it did not actually answer your question of why.)
By the way, the reason there are three pairs is the same as why an ATX power supply has multiple wires of the same color (voltage) going to the main connector: too much amperage for single wires and too much amperage for single connector pins.