Another lighting question on T5HO

[bfr57]

My garage has 16' ceilings and is 32' x 80' with skylights and white insulated roof. From what I'm reading here, I need high bay lights. Looking at a lighting display at HD, the T5HO stated high bay and are far brighter then anything else. Is there any downfall to these fixtures? How long do the bulbs ususally last? I don't want to have to rent man-lift every year to R&R bulbs and ballasts!

 

[madosta]

T5HOs would be awesome for that height.

You MIGHT want to check your local electrical/lighting supply (Graybar or similar) for some T5HO 4-6bulb fixtures at 4' and 8' as their prices differ over what HD has.

They also can provide you with a different selection of bulbs - e.g. personally I like 5000K color temperature and they can get you that in T5HO.

The bulbs last a LONG time. I have yet to replace any T5HOs, but someone might be able to chime in on the commercial/daily life of the bulbs.

 

[2ManyProjects]

My garage has 16' ceilings and is 32' x 80' with skylights and white insulated roof. From what I'm reading here, I need high bay lights.

Maybe.

The term "High Bay" is nebulous, at best; and there is no hard-and-fast definition of same. The closest thing to such a definition you'll ever find is that a "High Bay" fixture concentrates more of its output directly downward, as opposed to letting it spread out to the sides. Hence, the illumination is brighter directly under such a fixture than it would be with an otherwise equivalent non-"High Bay" fixture; but DIMMER once you move a few feet off-center. IOW... It's a trade-off.

As a VERY general rule-of-thumb, because of their above-noted "more focused" output, you will want the fixture mounting height (which may or may not correlate to the ceiling height) to be at least 12-15 feet before even considering anything designated as a "High Bay" fixture. And even then, there is no rule which states you MUST (or even "should") use such fixtures.

Looking at a lighting display at HD, the T5HO stated high bay and are far brighter then anything else.

Be VERY careful when attempting to make such judgements in retail stores and similar; it can be quite misleading. The fixtures are rarely (if ever) installed in such a way to even roughly approximate the way they'll actually be used. And staring directly at a light fixture mounted (even relatively high) to the side of an aisle display will often give a VERY distorted impression of "brightness" (and one which probably actually correlates more to "intensity" than the actual total light output -- i.e., the physically smaller source makes the light SEEM brighter than it really is).

Is there any downfall to these fixtures?

See above. The main "down side" is that they MUST be mounted relatively high in order to permit them to cover a reasonable-size area at working height, which in turn is why they so often use a large number (4-6, sometimes even 8) of high-output tubes). That in turn means more electrical power to run the fixture, a major chunk of which is effectively lost due to the relatively large source-subject distance. If you're trying to light up a large open space (think aircraft hangar, or large factory floor), they MAY be just the ticket. But for more intimate workspaces, they are often far from ideal.

All of which is a round-about way of saying that the ideal lighting scheme for YOUR shop/garage will depend greatly on EXACTLY what you will be doing where, within the space.

How long do the bulbs ususally last?

Per typical ratings (see http://www.1000bulbs.com/search/?q=F54T5HO), about the same as other common types of linear fluorescent tubes. But remember, these are STATISTICAL averages. With enough tubes installed, the odds are good that at least some of them WILL fall well outside that statistical norm.

I don't want to have to rent man-lift every year to R&R bulbs and ballasts!

Ballasts shouldn't be a problem, unless you "cheap out" too much on the fixtures. But periodic bulb/tube replacement SHOULD be considered. Anything mounted that high off the floor will require a SAFE means of access.

 

[Charles (in GA)]

The facility I work in has hundreds of Lithonia 8 bulb, high bay, T5HO fixtures mounted in it. Most are mounted about 95 to 100 ft off the floor. All have Phillips 4100K cool white bulbs installed in them, and all have photo cell sensors to turn them off if enough ambient light is available. Truthfully, they operate most of the time, less in the summer when the sun is bright and the doors are open. These were installed in Jan/Feb of 2011 and have operated ever since then, 24/7/365 on the photo cells. In the summer they are exposed to extreme heat that builds up in the roof area of the building. A few presently have 4 bulbs out, indicating a ballast failure, and there are one or two bulbs out here and there, but by and large, they are working just fine. No bulbs have ever been replaced. The ballast are, high input voltage ballasts, designed to operate on 347/480V as these fixtures replaced old sodium fixtures.

It sounds like you have a steel building, with the vinyl backed insulation inside. This is a very good reflector of light, and possibly the best choice (and probably the cheapest) is simple open strip lights.

Charles

This pic was taken during the lighting change over. The Lithonia T5HO fixtures are the three rows on the left, except for a few odd 400w sodium light pairs that were skipped over. the entire facility now, including the hallways, are T5HO lamps now, with the exception of a the loading dock and a couple of areas that have 400w metal halides that were "too new" to replace at the time.

 

[madosta]

Cool pic!!! That's a ways up there!!!

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