Setting up 2 rooms on a new circuit QB x 240v

[G.W.Bushes]

New to the forum and kinda new to LED.
I’m working in 2 6’x20’ spaces that I framed out in my basement, I want to light a footprint in each at 4’x16’. I have drivers and boards already but I’m having trouble finding info on a couple things concerning setting up a clean 240v circuit to run the lights on.
Rm1 will be 5 HLG-240h-c2100b each with 2 QB288v2 4000K.
Rm2 will be 4 HLG-480h-c2100b each with 4 QB288v2 3000k.
If I understand correctly, running on 240v, the HLG-240 will draw about 1 amp (5 amp for the whole run) and the HLG-480 will take about 2-2.5 amp (10 amp for the whole run). I’ve got a 30 amp 240v breaker, 10 gauge romex, all the appropriate gang boxes to run (straight down) from the breaker to the grow (about 15’), a plug to terminate that run at the near wall in each room, and one box for each driver.
I’m planning on running power from the breaker to the two outlets and mounting them at the end of the room closest to the breaker. From there running wire along the rafters back down the run with a plug end at the plug and gang boxes with splices all the way back.
My questions so far:
Do I need to run the 10 gauge from the plug all the way to the last light? It seems code says I can’t change the gauge of the wire on a 30 amp circuit.
Where do I drop wire size? The drivers have 18 gauge in them, can I tie that to the 10 gauge solid romex? Can I use a lighter wire past the plug since each string will be a lighter draw than the whole circuit?
Should I run 10 gauge the whole way and match the 18 gauge on the drivers and add a plug there? I’m trying to avoid buying a plug and plug end for each light right now because at 9 drivers, that’s pushin $25 each pair plus the 2 pair at the ends of the runs.
Thanks for any and all help, I’ve just about collected all the gear I need and I’m missing the last couple pieces of info to get it started.

[sdfoster22]

I am no electrician, but you only want to go to about 75% of the max rating for electrical wiring. Let's just say each hlg-420 is drawing 220v. Wiring 4 of those in parallel you would be drawing 220v @ 10a you would need something like this
https://www.googleadservices.com/pagead ... 5EQAvD_BwE

It is rated for 300v, 15a. Don't hold me too it, but I'm pretty sure on that.

Same goes with the hlg-240s, just make sure your power cord can handle the volts and amps provided by all the drivers. 75% is absolute max when dealing with electricity. Better safe than sorry.

You need to run the same wiring on the whole 30a circuit to every wall plug on that circuit.

[G.W.Bushes]

Tried attaching a picture of a drawing of what I’m talking about. I have 2 plugs and I want to wire the lights in each room all together onto one cord that plugs into a controller then the outlet, I have gang boxes and everything will be mounted to the rafters though.
The wire to the outlets from the breaker is 10 gauge, can the light strings be wired with 14 gauge (good to 15 amp) because the whole string won’t draw more than 10 amps? Or does it have to stay 10 gauge because it’s plugged into a 30 amp circuit?
At what point does the wire size drop to 18 gauge to match the driver? Everything I read says don’t change gauge, but 18 gauge is too small to run them all together. Do I run 14 gauge to all the boxes and splice 18 gauge down to the driver? Do I splice the 14 with 14 and run that to the driver and splice 14 to 18 there?
Thanks again!

[QuantumMechanic]

New here, but not new to the concept. My opinion, based on a lifetime in industrial maintenance:

I believe that you're looking at this from the wrong direction. Running everything off of one 30A-240V breaker might result in that breaker not tripping when you really need it to. It would be much better to split up the 30 Amp circuit over several smaller breakers in a sub panel. Yes, this costs a little more, but it's much safer.

A 30A-240V circuit has enough oomph to comfortably run a small welder without tripping the breaker. It's also capable of sustaining a pretty good arc for much longer than I'd be comfortable with. Connecting 18 gauge wiring to a 30 Amp circuit could result in fried wires and the potential for fire, if there's a problem in the circuit.

I have to assume the the drivers are internally fused, but what happens if, let's say, the 18 gauge wires somehow get mashed ahead of the fuse?

Odds are everything would be fine with one big breaker, but stuff happens and it's often spectacular stuff when it does.

[G.W.Bushes]

That’s excellent, thank you. That makes a lot of sense.
I’ll probably have another question but that’ll get me going at least.
Thanks!

[LEDG]

New here, but not new to the concept. My opinion, based on a lifetime in industrial maintenance:

I believe that you're looking at this from the wrong direction. Running everything off of one 30A-240V breaker might result in that breaker not tripping when you really need it to. It would be much better to split up the 30 Amp circuit over several smaller breakers in a sub panel. Yes, this costs a little more, but it's much safer.

A 30A-240V circuit has enough oomph to comfortably run a small welder without tripping the breaker. It's also capable of sustaining a pretty good arc for much longer than I'd be comfortable with. Connecting 18 gauge wiring to a 30 Amp circuit could result in fried wires and the potential for fire, if there's a problem in the circuit.

I have to assume the the drivers are internally fused, but what happens if, let's say, the 18 gauge wires somehow get mashed ahead of the fuse?

Odds are everything would be fine with one big breaker, but stuff happens and it's often spectacular stuff when it does.

Great info - thanks for sharing this.