I got ya now, I thought he was just saying (or rather meaning to say) that the lighting should be run on 120 through a timeclock and that other needs could be put on the remaining circuit. But there's nothing to stop them from running a 30amp 120 circuit. I also see no problem with loading the circuit more than 80%, especially under these circumstances. Unless the end user is a complete jackass. We only make shit idiot proof for the general mass of idiots. The code recognizes and is less restrictive for supervised installations. I have never actually had a grow room, but from what I am reading most experienced growers and respected community members recommend things like replacing the lamp before it's useful life is over, regular cleaning, etc. The user has his/her hands on these on regular basis maintaining or moving them. Any problems will be caught long before Johnny Homeowner would notice a problem with the HID lighting up his driveway. It can be assumed that the lighting is going to be on a routine cleaning/maintenance schedule in these cases. I still wouldn't 100% load the circuits, but I'm not scared to go over 80%. Many times I've seen breakers pefectly happy running beyond their rated capacities.
To be honest I have run circuits past 80% as well. But I know the risk. And yes I have seen breakers go past their capacity as well. At work we had a 20A breaker trip 5-6 times a day. When I looked at what was on the circuit I just could not figure out why it stayed on at all. I did fix it.
But if the breaker is running past its rated capacity, what about the wire? The breaker is there to protect the wire, and if the breaker is not tripping, the wire is carrying more current than its rated for.
But A LOT of growers dont know jack about electric and are with all due respect, the mass of idiots. When they ask questions like , hey can i swap my 20A breaker for a 30A breaker, you have to treat them carefully and explain stuff to them. Lets face it, this board is for people who smoke pot and when they read these posts, they may be high.
You admit to never having a grow room. Well you dont interact with your lights as much as you think. My lights are always on ropes with cleats on the wall so I can adjust the height. I dont touch the hood or ballast often at all. As far as cleaning, at max, that will happen every 2 months because most growers are not going to open the hoods and try cleaning them over flowering plants.
When we tell people they can put 2 1000watters on a 20A circuit, lets just make sure we give them all the info, just not tell them its OK.
If they leave for the weekend, and the breaker trips, their plants get no light for 2-3 days and stresses the plants. A couple times of this and you have hermied plants