Frozen's 3x3 low headroom COB build

Hi all, this is my first post, please be gentle. I have an electrical background but designing LED fixtures is definitely new to me! I started my first grow a couple months ago and I'm hooked, but I definitely need some lighting upgrades. I have two grow areas but this is the one that needs the loving first. It's a 3x3x42" area, and I'm potting in milk crates lined with weed barrier, so there is 32" from the soil to ceiling.

For this build I have gone through alot of different designs but this is my current idea. 15 Vero18's mounted on 3 x 30" bars, 5 per bar. 3 x 3000K and 2 x 4000K. Run on 3 HLG-185H-C1050B's. It puts me at about 165 watts from the wall per bar, and I was thinking I could fill in the rest of the HLG's 200W with some smaller LED's like xml2's or something (I haven't had time to read up on these types of LED's in depth yet, looking for suggestions here). According to the COB calculator this will put me at 940PPFD before any 'filling in'.
Will mount the Vero's to aluminum plates and mount CPU coolers to the back of the plates. I'm assuming I'll be actively cooling them.

I was thinking of installing switches in parallel with the 3000K COBS so I can short them out and turn off COBs during vegging until the scrog net starts to fill out to save power. Is this a good idea?

Does this layout look good?
Is 3000K/4000K a good combo or would 3500K/5000K be better? Or another combo?
Can I get suggestions for smaller LED's to 'fill in' the rest of the bars? Also since I plan on running at 1050mA can I install multiple of these smaller LED's in parallel with each other if they are rated at lower current? (and install this parallel array in series with the COB's of course). Will current runaway be a concern in this parallel portion?
I'm in Canada, so I have access to futureelectonics, digikey, and mouser. Suggestions for products that are available at these 3 places would be appreciated, unless you know other sources I can buy without high shipping/duty fees. (edit; or long shipping times)
I was thinking no reflectors since I will be 28" MAX from the top of the dirt. Should I be using lenses?

Other suggestions for this build? Will this be an adequate spread you think? Would love to hear your constructive criticisms!!!

Thank you all for contributing to this board. RIU seems to be the leading community among cannabis growers when it comes to COB lighting thats for sure!

edit; please excuse my MS paint sketch. Its not to scale but you get the idea I think!
edit2; I just saw an idea I like which is using vynyl square tubing ducted to the existing room exhaust, would bring up eff. for sure! I already have the aluminum bars so I would just cut holes in vinyl fence posts to accomodate the sinks. Or if I don't connect to the duct I could just have an intake and exhaust on the tube and still only be running 2 instead of 5 fans per bar with decent fans. Does this sound right?

Sorry I keep coming up with more questions as I read and now I have a place to write them down instead of just forget them so I figured I would add a post instead of keep editing.

Vero uses a Molex EZmate connector. You can buy in 6", 12", 18" wire length 28ga or shorter tails fused to larger guage wire (20 or 18ga). Is a 12" 28 ga wire ok to run continuously at 1050ma?? I know it's a short run but really it's 24" per light x 5 lights (min) so 10 feet (lots), I don't normally deal with current ratings for such small guage but google says 226ma for 28ga wire. Is this generally acceptable to run a vero 18@30W?? 1050ma? If I had wired direct I would go with 18ga for everything!!! But would still like to minimize plices so if I can go with longer 28ga cable assemblies I will. Unless there are larger gauge cables I'm not seeing? I only found them on digikey http://www.digikey.ca/product-detail/en/molex-llc/0688014147/WM9592-ND/3880992 Here is the brochure http://rhu004.sma-promail.com/SQLImages/kelmscott/Molex/PDF_Images/987650-8361.PDF

FYI I am planning on using some Ideal push-in compression wire connectors that I know are lying around somewhere... I still prefer twisting my wires and using wirenuts (hence they've been on the shelf for years) or soldering but I will admit for low current like this I think they are great.

You may have noticed I'm trying to use parts I have lying around... Heatsinks, aluminum, electrical/electronics stuff. Trying to keep cost to minimum with this build. When I started growing I told myself I was only going to have 2 plants with 2 lights I got for free in a 3x3 plywood box. This has spiralled thats for sure. Damn ADHD lol

I guess I'll be using this as a build diary as well.

Yes on the wire. Pico EZMates are much easier to work with as well.

In my opinion, for the power you are running, the heatsinks are over kill. If you want to save on build costs, it might be cheaper to just use lengths of aluminum angle from HD. Mount the CoBs to them and see how much active cooling is needed to keep them around ambient temperature at the current you are running.

Putting switches on the DC side of the driver won't work. Well it probably can work somehow but you are playing with fire and putting both the CoBs and driver at risk. Just don't do it. If you want to run multiple arrays, use more drivers. If cost is a problem, you can use smaller wattage drivers per CoB that cost significantly less. You don't have to run Meanwell for everything.

Yes I am concerned about the rating of the switches I would be using, as they are rated up to 277vac but I am unsure of a DC rating. I will probably just spend the time rewiring, again the fewer devices and connection points, the fewer potential failure points.

So you are saying that for 30w that a cpu cooler is overkill? This was also an area I was unsure of as I only briefly researched it.

I really like the idea of the fence posts also because I could close everything in (safer) which I was kind of hoping to do later anyway so killing 2 birds. And I already got the aluminum plates for free I just need to cut to length. The plate will be mounted on the outside of the post but will be grounded, along with the driver casing which will be mounted on the side outside. Also thinking of mounting drivers remotely (beside vent intake).

How about instead of cpu coolers (bulky, heavy) I could get away with decent chipset coolers just epoxied on (small, easy to work, light, plentiful in my junk drawer)? If not I have some pretty massive heatsinks I could cut up to cover all the cobs and then maybe I could just drill holes in the PVC to vent it? Or run 1-2 fans low speed. There will be lots of air movement in the grow room.

It's my policy that I don't cheap out on things that can catch fire. I'm an electrician, I've seen more burnt wiring, ballasts, receptacles, switches, transformers, coils, breakers, insulators, you name it, I've probably seen an electrical fire involving it. Not cheaping out on drivers, especially when I saw the lpc is only 90% EFF. Vs hlg 94% EFF. 4% for a small price savings (25%?), but no dimming, nah. I rather buy all the features I want now even if I only build 1 bar at a time. Yes the Vero 29 or cxb/cxa may be 5-10% more efficient but also at least 200-300% the cost just for the 29. I may only grow 1-2 years so don't want to invest too much so I will take the loss. But not using cheap eBay anything for stuff that is powered on while I'm not home to monitor it unless it is UL approved minimum. At least I try to.

Edit;spelling is hard

Just work out the math for design. Figure out what you are running your chips at and the efficiency at that level, from there figure out the watts wasted directly on heat. Example, 25w @ 59% eff, will give you roughly 10w of heat to deal with.

To put that in perspective, e27 LED bulbs running around 15-20w produce a similar amount of heat. Look at how those handle heat and you will see that a giant CPU cooler is often overkill.

If you plan on running at high currents, eg. approaching nominal, then you do need a much better cooler. Efficiency seekers shouldn't have heat issues and are quite safe dropping weight.

Alright yes I never looked at it that way, so perhaps I might even be able to run passively with cpu coolers or cut up my massive ones, it would also get best airflow if I went to a 1 fan design with that one cut up vs a mix of different style cpu coolers. I just won't have enough for 15 of them, but I'm sure I can source another one cheap/free somewhere.

Also just to mention when I was using cpu coolers, they aren't all massive ones, so you might think I'm using more cooling than I actually am. We might already be on the same page

Disclaimer : I'm pretty stoned.