"Edwin Pawlowski" wrote in message
...

"Bob Adkins" wrote in message
...
On Sat, 15 Jul 2006 21:34:46 GMT, "C. Massey" wrote:


They why does my employer change out the fluorescent lighting about every
5
or 6 years even when they are all burning good? When they do, the rooms
are
so much brighter. Makes a huge difference.

I'm betting the replacement was wasted. That's because the lamps were
changes individually as they failed. In other words, the average age of
the
tubes they were changing out was far less than 5 years!

No, that is the reason to change out all the bulbs. At home we usually
change a bulb when it is gone. No big deal. In a factory or large
office, getting the lifts, scaffolding or whatever together, two employees
+ overhead costs, they often find it cheaper just to sweep through an area
and change 100% of the bulbs at one time. That way, there are few, if
any, changes between, thus the average is still very high at 5 years.

If one bulb goes, all the others at that age are probably not far behind.
At work, we don't change the entire plant, but will do a section at a
time. When you have 20' ceilings, it is cheaper to change what you can get
at once the equipment is in place.

Agreed. The use of 'group relamping' (replacing all bulbs at once even
though many are still burning) has some advantages even though some bulbs
are replaced prematurely. Since bulb life is pretty predictable, most of
the replacements will not burn out too soon. All the bulbs are from the
same stock (usually), so it avoids mixing up different 'colors' such as
'cool white', 'softwhite' and 'daylight' in an area. And as you mentioned,
the 'overhead' of getting crew, tools, and equipment scheduled. If 'group
relamping' is done on a performance basis (for example, whenever 10% of the
bulbs have burned out), then large areas of burned out bulbs are usually
avoided.

'Spot relamping' has the advantage that maximum use of each bulb is attained
and only a small quantity of replacements are needed to keep on hand at any
one time.

daestrom