T12 to T8 conversion

At my workplace we are wanting to convert our current T12 lighting to T8, and are trying to sort out the options. The majority of our current fluorescent fixtures, troffers I guess you call them, are the three-bulb type with T12's installed, with two separate ballasts in each fixture, the older magnetic rapid start type. Between the various options, we're trying to determine whether we should do either one or the other of the following two options or maybe something else:
Option 1: Go with low-watt "800 series" ballasts along with high-lumen 5000K T8 lamps (keeping three lamps in each fixture).
Option 2: Go with high-output ballasts along with "super T8" lamps (reducing number of lamps from three to two in each fixture).
Any comments/advice appreciated.

 

Deleted comment. Adding to the length................

 

Sounds like the same situation.

http://forum.doityourself.com/lighti...2-inquiry.html

 

I agree.

I still stand by my posts in the other thread. About your questions in this one:

About 90% of the lamps we use are 4100K color. It is the best balance between light brightness and color. 5000K are just too blueish. You can still stay with an 800 series just get a 841.

I would suspect any savings of reducing 1 lamp per fixture would be offset by the HO ballasts and the shortened life of the lamps.

Info from the older post:

 

If I am clear that the recommendation here might be to go with 841 series T8 lamps with 4100K color, would an output of 3100 lumens be a good choice also? And perhaps along with ballasts with a low "ballast factor" of maybe .77 or .78, if obtainable?

 

I would suggest seeing what is readily available at your supply house. That way when it is time to service the fixtures later you won't be left in the dark.

 

Tolyn have the best answer in here the best thing is check with your electrical supply centre to see what they have on stock and what item may end up being specal order and someone will be there whom they are famuair with luminaire set up so they can recomened what type of ballast and go from there.

For myself normally I use standard electronic ballast most case but in few area I will go with high ballast factor if the customer request it.

Merci,Marc

 

I agree with recommendation to use the 4100K color lamp.
Our workplace just went through a 500 fixture T12 to T8 upgrade and the contractor started by using 3500K lamps.
It only took a half dozen fixtures to see they would be too warm.
We sent those back and settled on 4100 K and we couldn't be happier with the look.

We also got rid of our odd color CFL's and standardized everything to 4100K.
You can't imagine what our hospital looked like that had numerous renovations over the years..................kinda like a carnival atmosphere with the variety of lamps that we had.

 

Greg when you speak of the 3500K looking too warm what do you mean actually? Would they not be too good for an office environment or large conference room? Maybe I should at least try them (after ballast retrofit) to see if they'd be okay, or not bother?

 

You would do well to try out a few different types of bulbs before settling on anything.
Lamp K color is not the only thing that will affect the "look" of the bulb.
CRI or color rendering index could be different between bulb models or manufacturers and how it lights up a room will be different even though the color is the same.

The difference between the 3500K and 4100K in the bulbs we tried would have made the 3500's better in a waiting room or cafeteria but for task lighting we found 4100 to be better.
It is possible that the 4100's we chose had a higher CRI making colors look more natural.

Click image:

Image courtesy of bltdirect.com

 

Thank you for the advice, and the color scale.

 

Good rule of thumb is the T12 "cool white" is about a 4100K while a "warm white" is about a 3500K lamp. If you stick close to what you have now everything (paint, wall covering, furniture, etc.) will look the same.