This question has come up before, so let me spend a little more time on it.

How electricity really works:
Devices use what current they need, not what current is available to them -
a device that uses 2A, uses 2A because that's what it asks for, not because that's what it's fed.

A 30A branch circuit does NOT send 30A through everything on that circuit. It has the CAPACITY of 30A - you could say it has the ability to provide 30A. It will still only provide as much current as the device is requiring, no more.

Your Halos will draw only what they need, regardless of whether the circuit they're supplied by has ampacity of 5A or 30A. Either way, they will draw only what they require (1 or 2A).

On the other hand, if your device requires 10A, and you put it on a circuit that only has capacity for 5A, that's when the fuse will blow, protecting the wiring (which cannot handle the 10A that were asked for by the device).

You can put a device that only requires 5mA (.005A) on a 30A circuit, and it still will only draw 5mA.

Voltage is FED, Current is DRAWN.

-------------------------

Think of a simple 12v fuseblock - The battery feeds 12v to the fuseblock directly. Essentially* all of the battery's Current Capacity (Ampacity) is available to the fuseblock. From that point, different circuits leave the fuseblock through different-sized pathways. The larger pathways (10ga wire, for instance) can handle more current. The smaller pathways (20ga wire, for instance) can handle only a fraction of that current. All of those pathways are being supplied with the full amount of current that the battery has to offer. All of them. That's not what determines how much current is flowing through them.

The devices on the far end of each circuit determine how much current is being asked for. They determine how much current passes through. The designers of the wiring harness will note how much current is needed for each branch, and they will size the wire feeding that branch accordingly.

The fuses are there to provide a means of instantly disconnecting that pathway if too much current gets requested - such as in the case of a short to ground. If something asks for more current than the wiring can handle, the fuse will blow, and instantly remove the pathway. All of the available current is still there at the fuseblock, but it's not being asked for any more.


*I say Essentially, because even the whole fuseblock and everything it supplies, will never need the entire ampacity of the battery - not even the starter, the highest-drawing device in the entire car, requires the battery's full ampacity. So the pathway from the battery to the fuseblock is big enough to handle the highest theoretical load the fuseblock will ever require, which is something far less than the battery's full ampacity.