my hubby and I are remodeling the kitchen

we're debating about whether to put in rheostat lights or just regular
lights in one area.  My experience with rheostat lights is that they
always seem to buzz at low levels.  Is there any way to avoid this? 
Is it the bulb, or the fixture?  Would a higher quality of either do
the trick?

thanks

ts

While people use word 'rheostat' for any device which dims lights,
there really is  a difference between rheostat and dimmer.
http://www.factsfacts.com/MyHomeRepair/DimmerSwitch.htm

So, first suggestion is, do not buy a rheostat, buy a dimmer.
Rheostats  turn energy into heat, while dimmers  reduce your bill
and make your light bulbs last longer.

Some people use term 'rheostat dimmer' to mean a dimmer may be confusing.
The word rheostat, sometime called   'resistance rheostat' is described here:
Q: Does lowering the brightness of lights via a dimmer cause less
electricity to be consumed? If so, is it proportional to the degree of
dimness (i.e., does lowering the brightness by 50% lower the
consumption by 50%)? --RT Lennox, Strongsville, Ohio


A: Yes, dimming lights--with a modern dimmer switch-- consumes less
electricity. Years ago, dimmer switches used a variable-resister
(called a rheostat) to dim lights and these switches did not reduce
electricity consumption. They also generated much heat.
http://www.wonderquest.com/bugflip-collidingblackholes-dimmers.htm

When properly selected, modern dimmers will not create buzz
(they use solid state switching. The buzz was usually the
'transformer buzz' - not present in solid state switch)

Selecting a 'proper' dimmer can be tricky if you use fluorescent lights
(which are 5 times more economical than light bulbs).
  It may be a good idea to have electrician select the right one.

It is also important to know that dimmer is not the most effective solution.

Thrre way bulb is more efficient, (and guaranteed quiet).

http://www.dulley.com/tip/t1023.shtml

Often, buzz is caused not by dimmer, but by the 'ballast' used which
fluorescent lamp

http://www.faqs.org/faqs/electrical-wiring/part2/section-9.html

There was great progress in flurescent fixtures (fast start, quiet, dimmable)
but it may be complicated and more then you want to know.
http://members.misty.com/don/f-dim.html

So, to keep it simple:

Consider three-way bulb.

With regular (incadescent) bulb, you shoulf have no problem, no noise
with dimmer you buy at regular store - like radioshack.

Do ask if you want more info.

---

Request for Answer Clarification by timespacette-ga on 29 Nov 2004 16:39 PST

Hi hedgie,

I forgot to mention, I REALLY like to use full spectrum incandescent
bulbs. I'm not aware of where I can find them in the three-way
variety.  These are lights that are installed in a ceiling, with a
wall switch; are there three way wall switches?
Also, how do I know I am buying a dimmer that won't buzz?

If you can find any online sources for these items, I would be happy
to add a tip to this question!

thanks!

ts

---

Clarification of Answer by hedgie-ga on 30 Nov 2004 23:35 PST

First, I want to appreciate Guzzi's contribution of lot of small
points on LEDs and fluorescents etc.

I will limit myself to incandescents - since that's clearly customers preference. 

Three-way bulb is a bulb with two filaments.
It works like 50W bulb when one filament is used, and has same spectrum as
ordinary 50W bulb, or it uses 100W filament, or both.

I have found Froogle (a variant of Google, specialised to products) best way
to look what is on the market - and at what price.

Gere is Froogle response to the search term : Three way light bulb

http://froogle.google.com/froogle?q=three++way+light+bulb&btnG=Search+Froogle

and here for three way light switch:
http://froogle.google.com/froogle?q=three++way+wall+switch&btnG=Search+Froogle

So, three way light switches are on the market.  They are just like
ordinary switches in one housing. Three way way needs extra wire from
fixture to the switch. You did not stated if you are doing the
instalation yourself, or having an electrician to do it. Either way,
general remodelling may be good time for adding that extra wire.

The question : Also, how do I know I am buying a dimmer that won't buzz?
Hes really easy to answer: You do not. Not for sure. The issue of buzz is 
complex and no one can guarantee 100% that a circuit will not produce
a buzz. It may have to do something with the ground loops or radio
interference and it
can be fixed but requires some measurements. 
Here you can see that even the " ultimate deluxe .." dimmer switch ad warns:
 
      ....... may produce a subtle humming sound.......

http://store.yahoo.com/smarthomeinc/lightingx10.html

BUT  note: this applies to motors and other INDUCTIVE loads (which includes
fluorescent lights and electronics). Your case has only RESISTIVE load and
chances of humm are - a guess - less then 1 in a million. 

So, I suggest you do not worry about it. You neighbours may have and old
style (variac) dimmer which are not being sold anymore. Here is a somewhat
technical Application Note, which explains a bit about the 'inductive' vs
'resistive' loads and ground loops. 
http://www.dataforth.com/catalog/bb/221_550299873.pdf

Since you are adding purely resistive load, chances of creating an
inbalanced circtuit are very very small.
 When it happens, circuit may have a one 'noisy' component - but
sometimes it is hard to pinpoint the source - since the current
oscillation is  a condition
of the whole network. However, almost always you find some components like
motors, transformers, chokes .. which add 'inductive' loads to that network. 
So,
I would conclude that the 'buzz' of dimmed circuits, which you remember had
some such loads, motors or ballast of fluroresscent lights, and you will not
have that problem when you go with incadescent bulbs.

Hedgie

---

Clarification of Answer by hedgie-ga on 01 Dec 2004 00:16 PST

I want to add a link on use of dimmable light in concert hall


Lighting fixture and lamp type selection was reviewed by the lighting
consultant (Fisher & Marantz, New York City) and the acoustical
consultant to make sure that the incandescent lamps used in the
concert hall and other noise-critical areas would not "buzz" when
dimmed. The selection was limited to "A" lamps, "R" reflector lamps,
and tungsten-halogen, endprong, reflector lamps. No ballasted fixtures
are located within the noise-critical spaces.
http://www.ecmweb.com/mag/electric_controlling_building_noise/



and a specific source of parts (but do visit your local Home Depo as well):

source:
http://doityourself.com/store/electricalandlighting.htm

ballasts (to be avoided)
http://doityourself.com/store/fluorescentballasts.htm

three way bulbs (to be used)
http://doityourself.com/store/3waybulbs.htm

three way switches (to be used)
http://doityourself.com/store/3wayswitches.htm

What are these R-lamps theu used for a concert hall?


ERCO Guide - R and PAR lamps - Properties 
http://www.erco.com/en_index.htm  (good source of ideas and technical info)

 in particular
 ... reflector and parabolic aluminised reflector lamps. The
continuous spectrum of the incandescent lamp results in an excellent
colour rendition. ...
http://www.erco.com/guide_v2/guide_2/lighting_te_94/r_and_par_l_1616/en/en_r_and_par_l_pr


Gaudy - but extensive description of light sources:
http://maxpages.com/durotest/Incandescent_Lighting

Abd - just be fair - new CFLs with electronic ballasts are beter behaved than 
the old fluorescents - and can be dimmed quietly. Spectrum and CRI
improved too in some cases
http://www.betterbulbsdirect.com/productSubCfl.html
http://www.sunalite.com/

What is CRI?
. A lamp's color rendering ability is measured on the Color Rendering
Index (CRI), a scale from 0 to 100 (although negative values are
possible). Incandescent lamps have a CRI rating of 100. The higher the
CRI rating, the better the lamp's color rendering ability is. The
rating is provided in the lamp catalog. CRI ratings are only useful
when comparing lamps with the same color temperature.
http://www.lightsearch.com/lightnow/articles/indoor005.html

thank you very much for ALL THAT INFO!

cheerios!
ts

Couple of small point. The buzzing associated with dimmers comes from
the interference suppression choke. Some do it, some don?t.
Technically the solution is quite easy but it adds a wee bit to the
cost. On the basis of the more you pay, the better the product. Were
life so simple.......

If you are considering halogen bulbs, whilst dimmers are often
recommended for them, they tend to shorten the life of the bulbs.
Reason being that the small glass envelope must be maintained at a
high temperature for the evaporated halogenated tungsten to be
de-halogenated and allowed to redeposit on the filament.

Probably more info than you require, but the bulbs aren?t too cheap.

If you *really* want to get cool, white LED lighting is coming on
line. Not sure if dimmable units are available yet. Still very
expensive but economical and will last maybe 100,000 hours.

Best

hi guzzi!

I really don't like halogen bulbs!  Don't know about LED lights . . .
don't they give off a slickly green color?  What I want are full
spectrum bulbs, that would be best . . . see clarification above.

thanks for looking at this,

ts

Hi. Obviously hedgie has to present the official answer but since I?m
here at the mo....

Full spectrum bulbs are a bit ?difficult?. Apart from arc lamps,
nearest one can get to it are photoflood lamps but they last for a few
hours. Halogen are not bad, especially since the eye adjusts, but
still a bit short of blue. Standard incandescent are actually very
short of blue, as can be seen on photoes taken under that light.
Fluorescents come out bad too though some claim daylight, including UV
:-

http://www.avitec.com/avihealthN.html

Metal halide are possibly best, but usually only in high power and
they need special connection:-

http://www.plantlighting.com/growlights/growlights_207.php

http://www.plantlighting.com/growlights/growlights_207.php

You may have come across the ?daylight? bulbs intended for artists and
the like, which are standard incandescent with a blue coating. Problem
with them is that when you change rooms, unless they are all lit the
same way, everything looks like it has a colour cast.

http://www.lightbulbs-direct.com/search_results.asp?svalue=day&show=near

Some white LEDs are indeed greenish, some bluish and some with a mix
of both. But they are getting better. Could give the low-down but too
much info I think. Only thing you can do if you are considering all
alternatives, such as LED, is look for those which claim daylight.
Daylight colour graphs are readily available. They are sometimes
overlaid by light manufacturers graph to indicate how close their
bulbs match the spectrum. Daylight is of course a variable thing but
there are ?standards?. Here?s an interesting link which offers
daylight bulbs and graphs :-

http://www.outsidein.co.uk/solux.htm

Daylight lights are generally specialist application though. Most
lighting is not required to do a particularly good job because cost is
the defining factor and eyes adjust.
Interesting specialist site with dimmable daylight fluorescent :-

http://www.bhphotovideo.com/bnh/controller/home?A=details&Q=&is=REG&O=productlist&sku=248905

and....

http://www.datacolor.com/products_lighting_tru-vue2.shtml

Daylight LEDs and other LED bulbs are going to be big. Dimming is in
theory simple but it would generally require a completely different
type of dimmer unless the LED bulb was specifically designed to
?interpret? the standard dimmer signal.

http://www.wattbusters.com/LED_Lighting-p-1-c-263.html

http://www.kassoy.com/lamps/lamps002.html

https://secure530.sectorlink.com/led-bulbs/eShop/10Browse.asp?Category=Mains

Dimmable LED system

http://www.tmcnet.com/usubmit/2004/Oct/1088474.htm

The apple cart is likely to be tipped in the near future by LEDs but
at present they are still getting their legs. Maybe hold off these in
the meantime unless you are really keen to spend time and money on
them. So if you want daylight(ish), the most practical is either
(some) fluorescent or halogen but compact fluorescent can?t be dimmed.
So that leaves halogen which can shorten life. Also, when a halogen or
standard incandescent is dimmed, the colour becomes extremely
non-daylight.

As for which dimmers are noisy, I would suggest you see what friends
and neighbours have. One can take them to bits and ?cure? them but
this is specialist stuff.

By 3 way switches, do you mean a single 4 position switch which
switches off and one, two or three lamps (tongue twister) or a bank of
3. If the latter, they are around, but not the former as far as I am
aware. You can get remote control bulb holders too BTW.

Perhaps the best thing to do is decide upon priorities and check out a
lighting store. Take along coloured (colored) material and see what it
looks like at a window then try it under the lamp. You?ll probably
find that most LED lamps lose red. Avoid these. Incandescent always
lose blue and fluorescents are variable; sometimes losing, sometimes
enhancing green.

Confusing isn?t it. Can discuss further if you wish, and of course I
defer to hedgie.

Best

hey guzzi,

thanks for all this; it'll be a while before we digest it all . . .

if I have more uncertainties about it, I'll post another question

this is exhaustive!  (and remodelling is exhausting!)

ts