mm wrote:
On Wed, 25 Jul 2007 12:23:07 -0500, bud--
wrote:


Jeff Wisnia wrote:

Chris Lewis wrote:

According to Jeff Wisnia :



When you are replacing the dimmer, go to Rat Shack and pick yourself
up an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the
fuseholder in series with the hot feed to the dimmer (it should fit
inside the dimmer box) and you'll be pretty well be protected against
a future burnout. You may have to replace a burned out fuse, but the
dimmer should be OK.




That's just what I did with the four table lamps in our home which
are fitted with "touch dimmers". After the second dimmer blew I added
2 amp fuses to all of them. I've probably replaced six fuses in the
last five years, but all the dimmers are still alive and well.


I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.

Thanks, I realized too late that I forgot to mention that.

Not to be pedagogical, but I sized the fuses for my lamps by looking up
the specs of the triacs in my lamps' touch dimmers, the ones which were
punching through, and found on their maximum I^2*t rating. (eye squared
times tea)

Then I looked on Buss' website and found that the blowing energy (also
expressed as I^2*t) of their 3AG 2A fast blow fuses was somewhat less
than that of the triac, so I figured it should work.


I am sincerely genuinely impressed. The application is specific to the
triac and type of Buss fuse used, but has a good chance of working in
general.

Nitpicking - also check the fuse voltage ratings, and fuseholder ratings.

There may be more room to install a fuse at the light fixture.


Right, but in the dimmer, there might be room for a glass fuse without
a fuseholder. Either one with pigtails (wires soldered to the ends)
or small endcaps that are barely bigger than the metal ends of the
glass fuses. I don't know what Jeff actually used.


Well, as long as you sort of asked....

All four of the table lamps with touch dimmers in our home are Asian
styles with "full metal jacket" brass bodies. I installed the touch
dimmers in all of them myself, inside the lamp bases.

When the time came to add those fuses I Installed panel mount 3AG fuse
holders through holes I drilled in the side of the lamps bases, near
where the lamp cords exited.

Things being what they are, every few years we get a new cleaning person
and it sometime takes a little time for them to get used to those touch
switches. So, after the first few housecleanings (we're absent when
those happen) I'l maybe find the original manual switch on a lamp's bulb
socket turned to the OFF position, and once a lamp wouldn't turn on when
I touched it because the lady thought the fuseholder cap was a switch
and twisted it so that it sprang out enough to open the circuit. G

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.