What is the lowest temperature at which a T8 lamp will operate?

How much light do they produce at sub-zero temperatures when they don't operate properly?

I'm looking at an equipment shop on a farm. It might never be used in the winter or it might be heated when it is used.

Low bay HID hang too low for the equipment and T5 HO in an enclosure that will work are too expensive for something that might never be needed. Is T8 even an option?

A good place for info on lighting IMHO is RUUD Lighting.
THey sell direct to contractors, and have good quality products IMHO

Based on a quick search, T-8 are OK to zero degrees F.

My past experiences in cold facilities were that HO lamps worked the best.Check out RUUD is you want.

www.ruudlightingdirect.com

Thanks.

I was hoping someone in a northern climate had some in a garage and could tell me how they behave below freezing. Like flicker but get better as they warm up or are dead at a certain temperature. It seems if you put a protective sleeve over them, they warm up and work at colder temperatures. I think my customer wants them, but I need to know what I need to add for the really cold days.

Just a side thought. The application engineers at RUUD were more than helpful over the years that I was an active contractor. You may consider running your situation by them. Last I heard it was a free service.

I've installed a number of box-store T-8's in places like unheated garages. In Reno,winter temps often typically to around +20F; the coldest I ever encountered (in Reno proper) was -3F.

The results? All cold weather does is extend the 'low light' period, before the bulbs reach full bright. Perhaps as long as 15 minutes of gradually increasing light.

Hi there twh,
Sorry to come in on this thread so late.
Fluorescent lighting of any kind is pretty temperature dependant.

When you lower the temperature of a fluoro tube, it affects how the ions inside the tube strike the internal phosphor coating that produces visible light.
One way around this is to use an enclosed fitting, this gives you two things, all control gear emits at least some sort of heat, this will keep the tubes warm enough so that they will give optimum light output.

Also, with colder temperatures you usually have more humidity, an enclosed fitting keeps this humidity out (provided the conduit to the fitting is sealed/glued) and saves you needing to replace fittings that have corroded to bits in a very short space of time.

Regarding your question of T8 vs T5, T5 fittings give you a higher light output from the start, for a comparitive length of tube, vs the T8.
Even in so much that some places over here in NZ are starting to replace their low and high-bay lighting with the T5's.
I've used quite a few of the newer T5 fittings in various places and I must say, they are a significant jump in light output over the T8 fittings.

The only real caveat to what I've said above though is in when you're using them as a suspended fitting (hung from the roof with chains), they can swing quite a bit if there is a lot of wind around, due to their light weight.

I hope this is of some use to you.

Thanks guys. Your input does help. In the end, the customer liked the idea of several types of lighting for different purposes.

He opted for one circuit of flood lamps to get him in and out quickly. They are instant on and cheap. He can change to LED bulbs later, if he wants.

For work light by the overhead door, he has four 400W MH yoke mount, high on the walls and directed at the work area. Think of it as where you would have a friend hold a trouble light when you work under the hood of your car. It wouldn't be above the hood.

The overall lighting will be T8. It's fairly inexpensive and he can live without it in the very cold. He doesn't plan to do a lot of work in a freezing shop.

The goal was to hit emergency lighting levels to walk to the equipment, parking garage levels for checking oil and mechanic's garage levels for repair work. I hope that either he likes it or is forgiving if he doesn't. When it's done I'll try to remember to take pictures. They might be a good lesson of what not to do.

twh:

Adding a personal 2¢ to the previously posted Messages...



I have mentioned the following scenario before, so in the spirit of redundancy I proudly mention it again!

Per the Design-Build of a large Industrial Cold Storage Warehouse, an Illumination Maintenance follow-up was performed by myself and another EE. The tasks involved taking Foot-Candle readings at various points / locations, at a work plane of +2.5 Feet above Floor level.

Target Ambient Temperatures per Function Area:

A: Loading Dock: 4.4°C (40°F) Apx. 15,000 Sq. Ft.
B: Cold Storage; Warehouse Freezer: -20°C (-4°F) Apx. 65,000 Sq. Ft.
C: Cold Storage; Spec. Freezer: -40°C (-40°F) Apx. 1,000 Sq. Ft.

Per Design, the Installed Lighting for the Loading Dock and the -20°C Warehouse Freezer was built around our typical F54 T5HO 5000K Lamps, installed in 6 Lamp High Bay Fixtures, driven by Programmed Start Ballasts.
400 Watt Pulse Start Metal Halide High Bay Fixtures with Magnetic Reactor Ballasts, were used in the -40°C Spec. Freezer

Several Months after Final Commissioning and Start-up, the Client's Maintenance Staff installed several Eight Foot Fluorescent Reflector Strips in the Loading Dock and the Warehouse Freezer.
These Luminaries used T8 Standard Medium Bi-pin Lamps (265ma-430ma) with 4100K Color Temperature, driven by standard Electronic Instant Start Ballastry.
A mixture of Luminaries using (4) Four-Foot F32T8 Lamps, or (2) Eight-Foot F96T8 Lamps had been installed in both areas.

At the 40°F Loading Dock, the Quantity of Light Output for the T8 Fixtures was noticeably lower than the "Perceived Normal Output" of a given F32T8, 4100K Color Temp.
There was at least a 25% reduction in output Lumens from the T8 Cold Cathode Operation in the 40°F Ambient, as evident by Foot-Candle readings, and in comparison with an equivalent Lamp operated in a nearby Office; where the Ambient was +70°F.

The F54 T5HO High Bays were performing at, or better than our original target design prediction of 35Fc avg.
Quite impressive for Fixtures in operation for 18 Months! Lumen depreciation was less than expected, but this Facility is for Food-Based Logistics, so routine Maintenance keeps the dust from building up.

BTW, the T5's were Ceiling mounted at +24 Feet A.F.F., and the T8's were Chain Suspended at +10 Feet A.F.F., so the T5's likely had more Heat surrounding the Fixtures.

Lamp operation at the -20°C Warehouse Freezer was much different for the T8 Lamps, but the same for the T5 Lamps.
The T5 High Bays operated as per design, with a target of 30Fc avg.

The T8 Lamps could not achieve a stable Lamp Plasma in this very cold Ambient, and as result, suffered from Hypothermia.
Clear indications of this were the extremely low Lumen output (at best, 10% rated Lamp Lumens), and the constant "Cork-Screw Swirrel" of Gases springing across the Lamp.

As to mounting heights, the T5's were Ceiling mounted at +40 Feet A.F.F., and, as with the Loading Dock, the T8's were Chain Suspended at +10 Feet A.F.F.; so once again, the T5's likely have more Heat surrounding the Fixtures due to their mounting height and location, than the T8 Fixtures would have.
The warmer, lighter Ambient Air being at Ceiling Height (Buoyant forces plus Solar Heat Gain), and the colder, heavier Ambient Air settling close to the Concrete Slab Floor.

FWIW, the output Lumens from the 400W MH in the Spec. Freezer was reduced apx. 30% by the extremely low Ambient Temperature.

Some important points here are:

1. Cold Cathode (Instant Start) Lamp Operation was used to drive the 265ma - 430ma T8 Lamps in the Suspended Strip Fixtures,
2. Hot Cathode Lamp Operation - via Programmed Start was used with the T5 High Bay Fixtures,
3. In addition to the Hot Cathode Lamp Operation, High Output or "HO" (800ma) Lamps were used in the High Bay Fixtures,
4. Area Lighting for the High Bays was divided into separate Occupancy Sensor Controlled Zones, where Four of the Six Lamps were turned Off after 30 Minutes of inactivity.
   The outer Two Lamps remained On until the end of the work day (16 Hours On, 8 Hours Off via Lighting Control Time Clock).

Man, that Warehouse was COLD!!! We would periodically run out to the 40 degree Loading Dock to warm up!!!

--Scott (EE)

Thanks Scott.

The first option I presented to the customer was T5 and he rejected them outright based on cost. He also rejected lo-bay HID because they hang too low.

T8 will work in the summer and in the winter only if he heats the building.

What else is there?

A bunch of these

Seriously, that is what I had on the motion detectors in my garage in Md for when it was too cold to fire an F40-T12 before you were done walking through..

I agree and I have a full circuit of incandescent floods.

Has any thought been given to LED 4 foot tube lights?

The customer rejected T5 because of the cost. I don't think LED is cheaper than T5.

The T8 ballasts are rated to -17 C. They might not produce any light at that temperature, but a couple can be re-fitted to LED if/when needed. Thanks for that idea.

Plastic sleeves cost about the same as lamps. I'm tempted to throw a couple in to see how they work.

"FWIW, the output Lumens from the 400W MH in the Spec. Freezer was reduced apx. 30% by the extremely low Ambient Temperature."

Wow, that is surprising to me! as hot as the lamps get i would think they could overcome that.
I've always been dissapointed with how fast metal halide lamps drop off in lumen output over time, the color temp drops and lumens drop.
In fact I have best results with open fixtures where the heat can't build up because they are always on. Lights are a major pain in my back. I'm lovin LED's