48" 4-bulb T5HO setup: question about bulbs

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Hi Everyone,
This is my first posting....I'm new to the board. I have been reading through the threads and learning loads of valuable information. In fact I've read so much I'm feeling a bit overloaded at the moment !!!
I just set up a wire rack in my basement ( picture to follow once I read the instructions on how to do that!!). The rack has four shelves. I have hung a 4-bulb T5HO fixture above the top shelf. The plants are 18" below the fixture. I have a mixed group of Catteleya hybrids and species as well as a few Bc and a few dendrobiums. I hung another 4-bulb T5HO fixture below that with another shelf of plants about 24" below it. That shelf contains a mix of oncidiums, 2 phaps. 2 phrags.a few brassovola and a few other assorted species.

My question is about the type of bulbs that I have in my fixtures, and how close the plants should be to them.
I purchased the fixtures and the bulbs at Home Depot. The bulbs are 54Watts, 5000 lumens, cool white. The packaging on the bulbs also says the color temperature
is 4100K. Im not sure what that means! Since there area 4 bulbs in the fixtures will there be enough light? too much light? what about duration?

I live in Rhode Island and have grown orchids for several years in a greenhouse under natural light and almost all have thrived. I am moving my plants to artificial light because I turned the heat in my greenhouse way down this winter ( 45 degrees at night) to save on heating costs.

Any advise/help would be greatly appreciated. I am so thankful to have found this site!!!

Many thanks!
Sean