I have a LED COB with 6 strips, 8 A DC constant each, fed by 6 LED drivers (Meanwell HLG320H). They will be driven by the same 1-10 V dimming current.
Can I merge (put into contact) all 6 negative (-) output electrical contacts (8 A DC) or do I have to convey each of them separately? Why?
According to the LED driver terms, I'm wondering if I can connect multiple V- together; the goal is to make the cable set lighter.
I add that the COB has 6 separated strips, each with its + and - contacts.
It's not entirely clear what you mean here, but a couple possible things (drawing just three of your strips and power supplies for brevity):
simulate this circuit – Schematic created using CircuitLab
This is fine, as long as the wire marked "high current" is fine with carrying six times the current of a single LED driver. Just use a thicker wire for the negative side. You can also flip this around and use a single wire for the positive side if you use six separate wires for the negative side, though that would be an unusual configuration that would likely leave anyone repairing it in the future wondering why you did that.
This is fine with wires that can't handle the full six times current, and is recommended for keeping the devices at the same potential, if they're not connected elsewhere. The connection can also be on the driver end of the wires if that's easier. Again, you can also do this on the positive side, as long as it's only one side, but it would be... non-idiomatic, for lack of a better word.
And finally, it looks like this isn't what you mean, but just to be clear:
This is not fine, even if you have high current wires on both positive and negative. Most power supplies are not designed to be put in parallel like this, and will not work (perhaps even damage each other or themselves) if you try. It is possible to design power supplies for paralleling like this, but it takes special design and, in most cases, additional communication between the supplies to ensure they're working together instead of one doing all the work and the others doing none.
Not to mention, this would do nothing to ensure that all your LED strips get the same current, so one LED strip could well take all the current, overheat, and die, followed by another one taking all the current, overheating, and dying, and so on.
