Two Items:
1)---- I have an old carbon filament, probably hand blown, with a tip where it was sealed. I know this lamp was in use in 1929. It was in a walk-in closet. It hung on the electric cord and had a Pull-chain switch. I would go in the closet, turn it on, and give it a good swat so that it would swing around or back and forth. It made great dancing shadows.
If my mom was in the closet, I would go in, close the door and do the same thing. After a bit she would leave and let me play. Many years later, I'm not sure how long but it was after I had my doctor degree, I found out she was claustrophobic and would break out in a sweat when I did that. She never told me because she did not want it to affect me. And she would not leave immediately for fear that I would associate leaving with door closing. I was blessed with wonderful parents. Everyone should have wonderful parents---what a happy world this would be.
Myrna just called me to lunch. I will send this and then continue after lunch.
Enjoy,
Jim
OK tummy full, teeth not brushed, however, as usual, I am full of the stuff.
2)----My shop is 24 x 29.5 feet---minus Myrna's laundry, 7 x7 bathroom, water heater and FAU. It contains five, eight foot, twin T-12 luminaires and four, four foot long, twin T-8's. In the house one room contains two 8 foot T-12's and two 4 foot, 4 lamp T-12's. I have one 8 ft unit that is not installed yet.
I prefer the illumination of my 8 footers. They are 3500 degree K lamps. The 4 footers in the shop are 6500 degree K and give hospital surgery cold, almost harsh, illumination.
It sounds like I need to purchase three or four cases of 8 foot lamps. (Why do illuminating engineers call them 8 footers instead of 8 feeters? If you have more than one "foot" you have feet.) Replacing eight twin lamp 8-ft. fluorescents is going to run the price of a nice piece of ww machinery. What a waste of money.
Four foot, twin lamp T-8 fluorescent luminaires sell for less than ten-bucks at Lowe's. Of course they have magnetic ballasts, as all of the older fluorescents did. That won't hurt too much financially. (The electron ballast units run about $37 each in four foot luminaires. Only the US Treasury knows the price of 8 footers.)
Of course I should not complain. I got the 8 foot luminaires from my oldest son, Greg when he remodeled his automobile repair shop. He also gave me a wad of lamps. That was about 40 years ago. I had to start replacing lamps only a 2 or 3 years ago. It would not surprise me if one or two of the lamps are original. So for all of these years illumination has only cost me the electricity. However, I still don't want to buy new eight-foot light fixtures.
Enjoy (It does not sound like I am going to.),
Jim
I've been in the house for 19 years and they were put in 7 years before I bought the house. Figuring that the doors are opened and closed an average of 6 times a day that means the bulbs are lit for 2190 hours per year. 26 years =56940 hours of illumination 
...that works out to 6 hours per day, not 6 minutes. But my guess is that the light is on for 4-5 minutes per open and close, allowing time to get into and out of the car, unload car, then close door. So pick the 5 minutes per episode. 5 time 6 episodes per day = 30 min. per day. times 365 days = 1050 minutes per year. divide by 60 = 182.5 hours per year. times 26 years = 4745 hours. I'll let you figure up how much it cost you to run that bulb for that many hours. 
