Re: T5HO vs T8


jeremy_ho@xxxxxxxxxxx wrote:
> - some fixtures are sold with optional acrylic plates available to
> protect the bulbs, I guess they are more or less a diffuser. Some kind
> of diamond /pyramid pattern, would these reduce the light output? By
> how much?

They diffuse the light only if it is already controlled - a bare lamp
is pretty much diffuse anyway. They diffuse the source more though, so
if you had a small diameter lamp like a T5HO, then it would work well
to reduce the glare. They absorb between 8 and 30% depending on the
type, so it's easier simply to buy a bigger diameter lamp.

They do offer a little protection for your lamps - if you're moving
around some two by four and hit the fitting, the shield will break
instead of the lamp. (basic economics, the lamps cost a couple of
dollars at the nearest shop, the shields cost ten times that if bought
as an accessory and you have to order them through a wholesaler).

> - if a 6 bulb T8 fixture cost $160-$200. Would I get equavalent or
> similar results buying 3 pieces of 2xT8 shop lights from home depot (by
> lithonia) for ~$20 each, they use electronic ballast as well Maybe
> the 6 bulb one has a better designed reflector, but let say I put the 2
> bulb shop lights close each other for a direct comparison, seems like I
> saved alot of money if they provide similar results.

The only reason to buy the big unit is if you need the optics - but in
a low ceiling like yours, it's going to restrict the light to a small
area, where the lithonias will fill the space with light, and
importantly, light the vertical surfaces. (The majority of the
perception of brightness in a space comes from the illumination of the
walls)


> - disregarding the cost difference, do I get better results spreading
> out multiple 2 bulbs units in a garage? Seems that I will not have as
> much dark spots this way.

Distribute the light. If you want to boost vertical illumination, a
white panel behind the fitting will kick a reasonable portion in the
direction you want it to go. Alternatively, get a shop light with a
reflector (like an upside down V of metal) and cut off one side. There
are dedicated single direction units, but they aren't so common in
retail stores.

> - how high to suspend fixture from the ceiling is ideal? I think the
> ceiling is 9 ft

At that height, you could fix it on direct, or suspend it up to 18
inches. Much less than that and it'll feel like it is on top of you.
If you want softer light (slightly) then suspend it upside down and
you'll have more indirect and less direct light and the body of the
fitting will give the lamps a little protection from the aforementioned
two by four.

> - what kind of T8 bulbs (4 ft) should I get? I read there are chroma
> coated or something along those lines that are really good.

You should look for ones with an 80+ CRI. These will typically be
described as 830 or 840 or such like that. The 30 or 40 is the first
two digits of the color temperature. Personally, I tend to use 3000K
lamps (warmer) rather than 4000K lamps (cooler). They don't seem as
crisp or white, but they feel softer too.

> I still have not ruled out the T5 HO yet, originally I thought about
> getting one because I wanted a bright focused light near the engine
> bay. (as opposed to a 500W halogon flood) But I imagine when coming
> back from crawling under the car I would have to stare at the 4-T5
> might not be pleasant. The 6xT8 might be more ideal to look at while
> providing similar lumens.

A large source like fluorescent is better than a 500W halogen, as the
500W would cause strong shadowing. Try a T8 shop light with a
reflector shield (still just bent metal painted white, but it'll give
you enough kick. Remember to position it so that the hood doesn't
shadow the engine when open. If you want to really eliminate shadow,
you can use two T8 battens in a cross motif.

> Thanks very much,

You're welcome.

.

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