15 Year Old T-12s Question

[Rockford]

So, based on the title, it's obvious I'm out to make a change to save on the lighting expense. I'm currently running 10 8-foot T-12 fixtures with two tubes each.
What I'm trying to figure out is approximatelyhow many watts are these old ballasts burning compared to what the latest electronic ones use on T-8 fixtures. I looked everywhere on the existing ballasts and could not see and wattage rating.
Anyone have an idea?
I just don't want to trash perfectly good working fixtures if the savings isn't significant. If someone has some data comparing old T-12 ballasts to new T-8 ballasts that would be greatly appreciated.

Thanks all!
Rockford

 

[pattenp]

The input amps should be shown on the ballast label.

Edit: Use a clamp on amp meter on the circuit to see what amps they use. Then use some math to figure out the draw for each fixture.

 

[aandpdan]

Are they HO fixtures? What are you replacing them with?

F96T12HO 110 watt X 2 - mag ballast 230.0, energy saving mag 246, electronic 207.5
F96T12HO 95 watt X 2, ES lamps - mag ballast 209.0 energy saving mag 208.7 electronic 170

F96T8 59 watt x 2, ES lamps 101.0 watts.
F96T8HO 86 watt X 2, 150.0 watts.

From Excel Energy.

 

[cybrdyke]

There's variables. There are two different ballasts, standard are the really old ones, and "energy saving" have been around for 20+ years. If your fixtures are truly 15 years old, they could be either. The figures below are with standard ballasts. Subtract about 12 watts from total if you have energy savers. (It will say on the label).
Also, there are two different lamps, standard and energy savers. Standards are 75w lamps. Energy Savers are 60w lamps.

2 lamps F96T12 (75w lamps) + ballast = 175w
2 lamps F96T12 (60w Energy Saving lamps) + ballast = 131w
2 lamps F96T8 + ballast = 107w

68 watts savings from worst case scenario. If you use you're using your lights 3000 hours per year and you pay 10c for power, you would save $20.40 per fixture per year.

Hope this helps.
CD

 

[EOC_Jason]

It's probably not going to be much of a savings to replace perfectly good ones... But if the ballast dies in one maybe it would be worthwhile to replace it with an 8' long quad T8 fixture... (To me it's easier to handle and store the 4' tubes than 8').

But at the same time you would probably get some sort of volume discount if you bought a bunch of fixtures at once...

We have a bunch of 8' T12 fixtures, and buy spare ballasts from Amazon:

http://www.amazon.com/gp/product/B00AET2G1S/?tag=atomicindus08-20

That's for a multi-pack, I think you can buy them one at a time. But I'm happy with the Robertson brand. Cheaper prices than HD/Lowes...

 

[rsanter]

How much do you use them?
If they only get used sometimes, short time, weekends....
It won't matter as it will take forever for the savings to add up.
If you have them on all the time that's different

Bob

 

[Falcon67]

FWIW - My old shop had 12 T-12 4 foot shop light (Lowes) fixtures that I installed in 1997/8 when I built it. I changed them out to T-8 electronic zero start fixtures around 2006. I measured the current draw of the 12 before and after and the T-8s cut the light circuit power draw by 1/3. The T-8 fixtures were also Lowes sourced, basic $17 shop lights.

 

[danfromsyr]

some of us (Me) are changing out Tubes and ballasts for the LED flood/spot lights now on the market. they're waterproof (indoor/outdoor) and in my shop 24x24x12f main bay I replaced (4) 8ft 2tube units with (6) 30W LED units.

see some examples in this thread. http://www.garagejournal.com/forum/showthread.php?t=269983

and no 8ft bulbs to buy/store/replace.

 

[yeldogt]

I have them in one part of my studio ... many of the old fixtures were very high quality (mine are) and I have no plans on replacing. Was able to pick up a couple boxes of bulbs from a place unloading them -- have enough for two replacement cycles at $1 a bulb. I also like the output from the 8' lights.

I was glad to get the bulbs and I have two ballast that I kept from another area -- my concern was getting the bulb .. many places don't carry them anymore.

My don't run 24/7 -- even with our high electric rates the electric saving would never come close to paying for new fixtures ... and I don't like the light out of some of the new HO bulbs

 

[Rockford]

So, what "pattenp" suggested was a good idea- clamp a meter on and do the math. I did that and it's not adding up.
Ten 8 foot, twin bulb fixtures with 75 watt tubes equals, what I thought would be, a minimum 1500 watt load- not counting ballasts.
Well, I clamped right at the panel to the dedicated lighting circuit for the shop and turned all the lights on. Reading 11 Amps and 118 Volts. That equals 1,298 Watts, or 130 watts per fixture.
130 is less than the minimum 150 just for the two tubes??? Even taking out a percent here or there for inaccuracies and maybe age of the tubes, doesn't that 15-year old ballast consume some power??

See, it's the ballasts I'm really concerned about. There's not a huge difference in the T8 to T12 tubes when you do a one-to-one replacement.

Did I miss something really fundamental here?

 

[cybrdyke]

So, what "pattenp" suggested was a good idea- clamp a meter on and do the math. I did that and it's not adding up.
Ten 8 foot, twin bulb fixtures with 75 watt tubes equals, what I thought would be, a minimum 1500 watt load- not counting ballasts.
Well, I clamped right at the panel to the dedicated lighting circuit for the shop and turned all the lights on. Reading 11 Amps and 118 Volts. That equals 1,298 Watts, or 130 watts per fixture.
130 is less than the minimum 150 just for the two tubes??? Even taking out a percent here or there for inaccuracies and maybe age of the tubes, doesn't that 15-year old ballast consume some power??

See, it's the ballasts I'm really concerned about. There's not a huge difference in the T8 to T12 tubes when you do a one-to-one replacement.

Did I miss something really fundamental here?

Maybe. Do you have old magnetic ballasts or electronic ballasts? Can you get a part number off of one of them?
CD

 

[BillK]

Rock,
I am going through the same thing right now. I only have 6 fixtures plus two big metal halide ones. but could use a few more to get the light the way I like it. The one issue to think about is the price and availability of the T12 bulbs. Seem to be getting harder to find, at least in this area. I don't think the savings will be all that much. I might start replacing them one at a time and see what the light difference is.

 

[404]

So, what "pattenp" suggested was a good idea- clamp a meter on and do the math. I did that and it's not adding up.
Ten 8 foot, twin bulb fixtures with 75 watt tubes equals, what I thought would be, a minimum 1500 watt load- not counting ballasts.
Well, I clamped right at the panel to the dedicated lighting circuit for the shop and turned all the lights on. Reading 11 Amps and 118 Volts. That equals 1,298 Watts, or 130 watts per fixture.
130 is less than the minimum 150 just for the two tubes??? Even taking out a percent here or there for inaccuracies and maybe age of the tubes, doesn't that 15-year old ballast consume some power??

See, it's the ballasts I'm really concerned about. There's not a huge difference in the T8 to T12 tubes when you do a one-to-one replacement.

Did I miss something really fundamental here?

The current waveform for these lamps is not a sine wave.. So the meter will not read it correctly. If you could get hold of an old electric meter for example and check consumption over time that would give a more accurate reading.

Another solution that might be less wrong is something like this..

http://www.ebay.com/itm/AC-110V-220...399?pt=LH_DefaultDomain_0&hash=item2343f4e987

But there is no way of knowing how correctly this is designed or calibrated.

The clamp meter should be correct on a resistive load, like incandescent light bulbs, heaters with no fans, stoves, hot plates, things like that.

 

[Rockford]

Thanks all, and that's an interesting point "404" had about the clamp on meters not reading it directly.
Thanks for the input.

 

[BillK]

Thanks all, and that's an interesting point "404" had about the clamp on meters not reading it directly.
Thanks for the input.

A clamp on meter will read correct if it is a "True RMS" reading meter.

 

[mark11]

I can't speak to energy savings but I guarantee you won't believe the additional light if you go to T8's.
Over the past two days we had all of our T12's replaced at the plant I run with T8's. The 8 footers were changed to quad T8's and the 4 footers were just changed over to T8's.
We were running 60W 8 footers and 34W 4 footers, everything was changed to 28W T8's and the light difference is amazing. We used 4100k in the offices (nice temp for the offices) and 5000k in the shop. As they got sections changed out the places they hadn't done yet just looked like the air was dirty. The light output is higher on the new bulbs than the old and we went from 4100k to 5000k, now everyone needs sunglasses till they get used to it.