Conference 7.286::home_work

    
    
    	Hello,
     I am getting ready to do the finish electric on my house. I am
    going to be using single pole dimmers in four places and would like
    to have a three-way dimmer circuit in two seperate locations.  I am
     thinking of using the Leviton(hope I spelledthat right) touch
     dimmers. They make single pole and also a three way pair that will
     allow you to turn the lights off,on, and fully dim to bright at
     eather location. Now for the questions, are they reliable?, how
    long will they last?, do any of you have them in your home now?
    
    
    
    				Thank you in advance,
    
    				      Joe
    

>     a three way pair that will
>     allow you to turn the lights off,on, and fully dim to bright at
>     eather location. 


I may be wrong, but this sounds a lot like the X-10 3-way light 
controller.  it actually has a switch at only one location, and the 
other location sends a signal to the 'real' switch to control the 
lamp.  If so, you may pick it up for less at radio schack.

Re: .1

	I think he's talking about the device that looks like a little 
metal plate on the wall that you touch to turn the lights on or off, and 
toch and hold to make the lights dim.  It's not an X10 device.

Re: .0
	If that's indeed what you're talking about, I used to hang out 
with some people who had one of those in their kitchen.  It always 
worked and was still working after 5 years when I left town, so I guess 
it's fairly reliable.  I never liked the idea of having a touch plate 
next to the sink, but I don't know how it's isolated.  Nobody ever got a 
shock, and many wet hands touched it.
					>>>==>PStJTT

    I'v had this type of dimmer in my house for about three years. 
    No real trouble yet, although they seen to respond to warn hands
    better than cold.  One thing about them is the price ~$18.00 for
    a single pole.
    
    Mark
    

    I installed several of these dimmers in my parents house about 8
    years ago when leviton first released them. I was working at a supply
    house and the leviton vendor GAVE me 10 to install to see how they
    worked. The do work very well and I haven't had a single failure
    on any of them. I belive the called them sensitron dimmers.
    I love DEC but I sure do miss those freebies.
    
    -j
    

    How do you add a wall switch alongside an existing switch in a
    finished room?
    Normally the boxes would gang together, but you can't unscrew the side
    of the existing box when there's sheetrock all the way around it.
    You can't hold the new box in with a moly-bolt since one side is
    right up agains the existing box.
    Any ideas?
    
    

    
    	Last time I did it I got a two switch box, cut the sheet
    rock out accordingly then jerked out the existing box and
    replaced it with the new one. The new box was the type that 
    clamped on to the sheetrock.
    
    

    
    	If the box currently in the wall is the fiberglas type
    	it is very easy to break it into manageable pieces and
    	remove it (I just did this last weekend) and neatly
    	enlarge the hole for the new box. Or, you could always
    	butt a box up against the existing box if you use the 
    	type that clamp onto sheetrock (I love those things, 
    	they make retrofitting so easy!).
    
    						* MAC *

I did exactly that; added a second switch (in this case, a fan
speed control) along side the 3-way light switch. The power feed
was at the base of the stairs so I was able to fish a feed to the
fan. I removed the switch, found which side of the box was nailed
into the wood.

I removed the box by using a hack saw blade to cut the nails
holding the box in place. I cut the dry wall to fit the double
box and used the drywall screws to hold the new box in place
(after removing the nails).

If you have a recipacating saw, the job would be a lot easier.

cal hoe

      Another  posibility  is  to get a double switch -- on that has two
      switches on a single mounting strap.  You use  a  standard  duplex
      outlet  plate  to  cover  it.  In fact it looks much like a duplex
      outlet, except  that  it  has  switches  instead  of  outlets  and
      differently  arranged  terminals  on the back.  Most/many hardware
      stores sell these with two single pole switches or with one switch
      and one outlet. If you go to an electical supply house I think you
      can also get them with "three way" switches  (for  controling  the
      circuit from two switches).
      
      The only problem with these is that its pretty easy to end up with
      more wires in the box than code allows. This is especially true if
      you have 12 ga wiring.
      
      As  to looks -- thats a matter of opinion.  Some people thing that
      the smaller switch plate is neater; other people  thing  that  two
      switches in half the "normal" space looks crowded and sloppy.  But
      its surely less work than retrofitting a larger box -- maybe a lot
      less work.

    If the box is metal, you can add another box along side of it. the
    first thing to do is to cut out a space next to the current box
    in the sheetrock or plaster. Next you want to remove the side plate
    from the existing metal box. There is only one screw to loosen,
    this is the hard part, take a pair of long nose pliers, offset if
    you have them and turn the loosen the screw from the top. You may
    have to make the hole on top of the box bigger to fit the pliers,
    just don't make the hole too big to be covered by the plate. Another
    trick is to use a heavy pair of linesmans pliers and bend the side
    plate in to release it from the box. Once the side plate is off
    take your long nose and back the screw off a couple of turns, not
    too far, you want to leave a few threads left on the screw inside
    the box. Take your new box, remove the side plate from it and make
    sure there are a few threads left on the screw that held its side
    plate on. When you join the two boxes, there will be a screw on
    the top and bottom to tighten. Remove the knock out for your wire
    and strip and insert it in the new box before you put the box in
    the wall. Now slip the box in at an angle into the hole, take your
    long nose pliers and pull out on the bottom of the existing box
    and line up the tabs, one tab will be on the new box and will slip
    under a screw on the existing box, one tab will be on the existing
    box and will slip under the screw on the new box. Do the same for
    the top.  When the boxes are together (this may take a minute or two),
    tighten up the screws holding the boxes together from the inside with 
    your long nose pliers on the couple of threads sticking down from
    the outside of the boxes. You are done. One hint- Try this with a 
    couple of spare boxes out of the wall to get an idea of how they 
    join together before you start.
                             
    
    							Chris

I attempted to install a light dimmer this weekend and ran into a problem. 
When I turned it on, a humming (fairly loud) started coming out of the electric 
doorbell/intercom one foot above the switch on the same wall. The humming got 
louder as I increased the lighting. 

Two questions (which will probably give you a pretty good idea of how little 
I know about wiring):

1. The light switch that I removed had a ground wire attached to it. There 
   was a screw on the metal face of the switch box, seemingly there for the 
   ground wire to be attached to it. The dimmer had no separate screw, so I 
   wrapped the ground wire around one of the screws used to hold the dimmer 
   in the wall box. Is there something else I should have done with this 
   wire?

2. The two wires coming out of the wall look identical to each other; the 
   two on the dimmer I bought also look identical to each other. Does it 
   make any difference which is paired with which?

Thanks in advance for your help.

					Jack

    
    	Dimmers are really just a fast switch, they switch power
    on 60 times a second and create a lot of transients in doing so.
    These transients radiate energy ( noise ) from the audio on up
    into the RF range. I've found that by turning off all the dimmers
    in the house I can get another 5db gain out of my SW reciever.
    I can't remember the brand name but there are dimmers that seem
    generate less noise but cost more ( $10 to $12 ). 
                       
    
    

    	I may be wrong but I thought that light dimmers (especially
    since we're talking about such low current) are nothing more than
    variable resistors ?
    
    	At any rate, it does seem as though you are getting some sort
    of noise from the dimmer as I assume you didn't have the problem
    with a regular switch. One quick question, is the dimmer mounted 
    in a plastic or a metal junction box ? If it's in plastic box, you
    may be able to minimize the noise by replacing the plastic box with
    a metal box and using a metal faceplate. 
    
    	If you use a metal box, you can attach the ground wire to the box 
    and it will be connected to the dimmer electrically when you secure
    the dimmer to the box.
    
    	Ray
 

A dimmer is definitely NOT a variable resistor, most models can handle 500
to 700 watts (that's not low power).
    
If I remember correctly a modern dimmer is actually a Triac, which uses a 
variable resistor to regulate the firing voltage. If you were to examine the
wave form, you would see the sin wave being cut vertically, thus the output
at 50% power would look something like this...
    
   
          ****
        *    *
      *      *
     *       *
    *        *
   *         *
  *          *
 *           *
             *
             *     
             **********           *
        	      *           *
    	               *          *
        	        *         *
    		         *        *
        	           *      *
    			     *    *
    			       ****
    					
If you are dimming close to the rated maximum wattage in addition to
Transmitting electrical interferance , the dimmer and even the filaments in
the bulbs may buzz. 
                  
Try a better quality unit available at a commercial electrical supply dealer.
                  
    Using a metal box, as previously suggested, may reduce the transmitted
    interferance.                                 
                                                  
                                                                            
Cheers,                                                                     
                                                                            
Peter                                                                       
                                                  
                                                  
                                                  
                                                  

If I'm not mistaken, the waveform in the previous note is reversed. That is, the
triac or whatever is controlling the voltage turns on at some time into the 
start of each half cycle rather than off. The sudden change in voltage at the
turn-on is what contributes to the radiated (RFI) noise. However, there is
another noise that I've noticed, and that is an audio noise which emanates from
the bulbs themselves. I'm not certain, but I believe that the filaments of the
bulbs actually vibrate at 60 hz due to the varying magnetic field surrounding
them. The degree of noise seems to depend on the actual brightness setting. 

Dave 

I don't remember the brand name of the dimmer (Luton or something like that) 
but it was the only one I saw at Somerville Lumber (regularly $16 on sale 
for $9). The dimmer is made up of a black plastic box with two wires coming 
out of the bottom and a front plate that is made out of something that feels 
like a very light metal. 

When I installed it I wrapped the ground wire around the screw that was used 
to bolt the unit into the box unit in the wall. The box unit in the wall is 
metal so even if the front plate of the dimmer isn't, wouldn't the metalin 
the box ground it???

    I made the same mistake....   They have dimmers that make NO noise.. 
    Go to a lighting store that electrical contractors go to  and tell
    them your situation..  They sell dimmers just for that... I went to 
    Ralph Pills   it cost about $20 for the dimmer and we haven't heard a
    Bzzzzz since...  Your better off spending your money on the right
    thing once....

    
    	I said 60 but actually the power is switched on 120 times
    a second ( every half wave ). A metal box probably won't do
    much good unless the wiring between the dimmer and light is
    also shielded, the wiring acts as an antenna.
    	I took a "good" dimmer apart once ( died for another
    reason ) and found a couple of coils inside, looked like
    RFI suppresion.
    
    

I have some questions concering adding a 110v outlet as show below
to a current 220 volt line which feeds my well pump.  I added the outlet
between the white ground wire and one of the black hot leads.

                                                       /
                                                      /20A Breaker
       <------ black -------------------------------o/|  o------------<
                                                      |
       <------ white -----+-----------------------o   |
  Pump                    |                       |   |ganged    (Panel)
  Motor                  --- 110V Receptacle     ---  |
                         ---                      -    /
                          |                           /20A Breaker
       <------- black ----+-------------------------o/   o------------<

questions:

1.  Is the effective rating of the 220v line 20 Amps?
2.  Will a load of more than 20amps in the outlet trip the double pole breaker?
3.  How do i ground the receptacle if i only have 2 wires: 1 hot and 1 return?
4.  Can i connect the white wire to also the green screw to ground the outlet?
5.  Is the above configuration legal?  I simply added the receptacle in-line
    in a already existing metal box located near the waterpump.  It was 
    just convenient.

6.  In a normal 115v circuit using 14/2 with ground wire, i notice that in the
    panel, both the bare ground wire and white wire attach to the ground 
    bar.  why thus, is another wire needed to ground the circuit if both the 
    wires are effectively shorted together?

Thanks.

-jim

    As per the usual points, I don't think that your configuration is to
    code. The 220 breaker should have both legs tied together, so if one
    leg trips, the other should also be tripped, but except for cost
    savings, this setup (a 220 V and 110 V on the same service) is not the
    greatest idea.
    
    As to grounding, the only place the neutral and ground are supposed to
    be tied together is at the service entrance. They must run independent
    after that point. The neutral is a current carrying conductor while
    the ground should not be.
    
    Eric

    	This is probably covered else where but I do not believe this
    is legal (to code). Although the white and ground are tied together in 
    the breaker box, this is the only place they should be. 
    
	It will work but should a fire result you can kiss your insurance
    goodbye. A licenced electrician would not wire it that way and it
    would not take a genius to figure this out if something happens
    as a result.
    
    	The white wire is considered the return wire. It is insulated
    and designed to be a current carrying conductor under normal operating
    conditions and designated to be that way. The ground is designed
    and designated (by it's lack of insulation) to be a current carrying
    conductor in abnormal circumstances. Electricians (that I've seen)
    tend to do a lot of work with the power on. If you sold the house and 
    the new buyer had an electrician come in to work on something connected
    to this, they would not expect this. You could be liable for anything
    that happened around this. 

    	If your going to do it yourself, at least do it the best way
    known (not always the easiest way).
    
    	There are probably other reason but these are the first to come
    to mind.
    
    	Ray
    

    BTW - The 20 amps on the breaker is I believe 20 amps per hot wire.
    20 amp wire would be 12 awg.

>    As per the usual points, I don't think that your configuration is to
>    code. The 220 breaker should have both legs tied together, so if one
>    leg trips, the other should also be tripped, but except for cost
>    savings, this setup (a 220 V and 110 V on the same service) is not the
>    greatest idea.
    
They are.  The 220v Breaker are actually two 20A breakers tied together
with a bar on the handles.

-jim

    	Looking at your reply again I noted you indicated the ground
    WAS insulated going to/from the pump. This negates one of the
    conditions I thought you had. 
    
    	It still leaves an issue of whether or not this is to code
    (which I suspect it isn't). The code is to be followed for reasons
    of safety and consistancy (which relates back to safety).
    
    	If the hot lead going to the pump (which happens to be the hot
    lead other than the one you're using for the outlet) shorts to ground, I 
    believe you will create a condition which will momentarily put 220v 
    across whatever you have connected to your outlet. You are also drawing
    more current on one leg of the pump breaker than the other. In and
    of itself this may not hurt anything but it may trip the breaker 
    depending on the combined load (i.e. what you plug into to outlet plus 
    the pump may be greater than 20 amps). A well pump typically draws 
    a healthy current, especially at startup, and I would expect to see 
    healthy voltage spikes on the outlet everytime the pump turns on.
    
    	There are probably other reasons (like what happens if the pump
    gets hit by lightning) but you probably get the general idea by
    now.
    
    	Hope this helps......Ray

>< Note 3604.0 by CIMNET::MIKELIS "Just browsing through time..." >
               



What you wired "may" be code legal.

NEC 210-4 Multiwire Branch circuits.

(c) Line to Neutral Load. Multiwire branch circuits shall supply only line
to neutral load.

Exception No. 1: A multiwire branch circuit that supplies only one utilization
equipment.

Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit
are opened simultaneously by the branch-circuit overcurrent device.
***************************************************************************
Questions to ask yourself:

Is your breaker double pole, single throw?

Do you have a "grounding" conductor in your circuit? (bare copper or green
 insulated)? You can't use the neutral (grounded wire) to ground your pump.

What is the total load on this circuit? What is the other equipment?
Running a pump  motor has complicated things a bit (motor load is calculated 
at 125%).
***************************************************************************
FWIW, I don't like this kind of circuit. It may be legal if wired properly,
but it's not good practice. (short cut).

Ross

    re: .1  Affect on insurance of code violation
    
    This keeps coming up so I'll repeat what has been said before:
    According to an insurance exec neighbor, presence of a code violation
    is unlikely to cause an insurance company not to pay, even if the code
    violation appears to be the direct cause of the loss.   As he told me
    it's more cost effective to simply pay up rather than face a complex
    litigation to determine who violated what code and where.  Where they
    draw the line is if the code violation was undertaken in order to
    deliberately cause a loss - this they treat the same as you burning
    down the house to collect the insurance - i.e., no pay.
    
    You are most definitely taking risks by not following code, but at
    least according to one major fire insurance company, it's not likely
    to affect any claims.

What .0 describes looks a lot like the way many 220v lines to appliances
work, that is, a 220v two-legged feed with some 110v usage in the appliance.
Clothes dryers, for example, have 220v heating elements and 110v motors
and lights.  Electric ranges have 220v elements and 110v lights and convenience
outlets.
Is this substantially different from what .0 describes?

- tom]

    .0 is not legal but your stove is - here's why:
    
    The use of common ground and neutral for 110V fixtures in 220v
    appliances is indeed, from a logical standpoint, what is proposed
    in .0.   There is some language in the code to cover these as
    exceptions - for one thing they have to be dedicated circuits - so in
    fact if you broke into the 3 wire line leading to your range outlet
    and put in a 110v receptacle the circuit would no longer be
    dedica(to the range).   The common enclosure of the appliance
    seems to be what counts to qualify for the exception.  As I read
    the proposal, it would only be legal if the 110V outlet was enclosed
    in the pump housing or a direct mechanical extension thereto.
    

>Is your breaker double pole, single throw?

 Yes, why?

>Do you have a "grounding" conductor in your circuit? (bare copper or green
> insulated)? You can't use the neutral (grounded wire) to ground your pump.

  No, the original pump circuit has 3 wires, 2 hot (black) and one 
  neutral (white).  i just wired in the duplex using the white and black
  wire.  The duplex is not grounded as is.

>What is the total load on this circuit? What is the other equipment?
>Running a pump  motor has complicated things a bit (motor load is calculated 
>at 125%).

 The only load on this circuit is the pump motor.  The reason i wired in the
 duplex outlet in the same line, was that i needed an outlet near a sofa 
 for a lamp.  Rather than wiring a new circuit, i did indeed take a shortcut.  

I don't mean to drag this out, just want to understand the possible 
implications of doing this sort of thing.

-jim

    NEC allows use of "combined" groundED and groundING (white & bare
    in type NM cable) for certain appliances such as ranges and dryers.
    To qualify, you must use at least #10 wire.  If you use cable
    (rather than conduit) you must use service entrance cable with
    two insulated conductors and a third non-insulated conductor.
    Also, the feed for the circuit must originate at a main panel,
    not a subpanel, since only at the main panel are the groundED
    and groundING conductors connected (the neutral busbar in a
    subpanel MUST be isolated from the subpanel enclosure, rather
    than being bonded to the enclosure as in service entrance).
    
    If the pump is 240 volts, then it sounds like someone used the
    white wire as a groundING conductor, which is against the NEC
    in this case.  Of course, it also depends on whether or not
    the wires are run in conduit, which itself would serve as a
    groundING conductor (although I'm not sure why they need a
    white goundED conductor for a 240 volt pump).
    
    I'd be safe and run your outlet off some other branch, and also
    check with a licensed electrician to see if your pump circuit
    really does meet the code.

>< Note 3604.9 by CIMNET::MIKELIS "Just browsing through time



Jim, If you re-read my reply (re:5), you'll see that I typed the
pertinent National Electric Code chapter. (Multiwire branch circuits).
And if you further notice, Exception #2 is what applies to your situation.
You must have an interupting device (circuit breaker) that is capable of
opening all ungrounded wire "simultaneously". This is why I asked if
you had a double pole, single throw breaker.

However, You are in violation of the code by wiring in an ungrounded recepticle.
See NEC chapter 210-7, 210-8.

Ross

>< Note 3604.10 by VINO::DZIEDZIC >
>                       -< Sounds like a violation to me >-
>>
>    NEC allows use of "combined" groundED and groundING (white & bare
>    in type NM cable) for certain appliances such as ranges and dryers.
>    To qualify, you must use at least #10 wire.  If you use cable
 
Be careful. NEC chapter 250-60 states #10 copper/#8 aluminum. Also, This
is *not* true for mobile homes.

>   (rather than conduit) you must use service entrance cable with
>    two insulated conductors and a third non-insulated conductor.
>    Also, the feed for the circuit must originate at a main panel,
>    not a subpanel, since only at the main panel are the groundED
>    and groundING conductors connected (the neutral busbar in a
>    subpanel MUST be isolated from the subpanel enclosure, rather
>    than being bonded to the enclosure as in service entrance).
 
This isn't pertinent to the originator's question. Since we're not talking
range or clothe dryer, the violation is: not having a grounding conductor
in his circuit.


Ross

    Re: .6 I don't think it's good to say don't worry about the insurance
    companys. You may have gotten some bad advice from this guy. It
    does matter. Negligence cannot be excused or accepted. If something
    is illegal it shouldn't be done. That's why electricians must get
    a license, to know the what's legal and what's not (in this case,
    definitely NOT.)

  I might get slapped on the wrist by the moderator for asking this, but:
  
    To pursue the issue of connecting the white neutral to the ground being
    allowed only at the service entrance, tell me if something is wrong with
    this connection:

     
     Clothes Dryer:  No spare breaker locations in service entrance, so use
                     a subpanel with 30 amp, double throw breaker.  Tap off
                     220 at lugs in service entrance with 10-3 with ground
                     Romex, tying white neutral and gnd to gnd busbar; 
                     run the wire to
                     subpanel, 2 hot wires to breakers, and neutral and ground
                     together on bus bar; run other side of breaker to hot
                     terminals of dryer outlet; run white neutral and ground 
                     from
                     subpanel busbar to third (center) terminal of dryer outlet.


          If this is against code, please tell me how to connect the neutral a
          and gnd wires after they leave the service entrance.  

          Did an earlier note indicate that this connection is ok for dryers?

         Thanks,  Steve

    I think the set-up you're describing would NOT fall under the
    classification of a subpanel in the NEC (I'd have to check the
    code to be sure), since the feed to the "box" is taken from a
    source which is not controlled by overcurrent protection (other
    than the main breaker).  BUT, I don't think you'd be allowed to
    use cable as a feed between the two boxes; a metal-to-metal
    connection boxes (conduit, nipple, etc.) would be required.
    
    With a REAL subpanel (with floating neutral) you'd need to use
    a 4-wire cable (two hots, a goundED, and a groundING wire).

>< Note 3604.14 by MFGMEM::S_JOHNSON >
>                        -< ground/neutral connections? >-


What you're proposing is a feeder tap. (see NEC 240-21). Yes, It can be done
in accordance with this article. (I typed the criteria and lost my line).

-	tap conductors less than 10 feet in length

-	ampacity of conductors = control device they supply

-	"	"	"	load they supply


_	protected in a raceway

-	don't extend beyound overcurrent protection device

NEC 250-60 states you can use the  grounded conductor as a grounding conductor
in a clothe dryer circuit.

re .15, .16


    So, what you're indicating to me is that this is okay, except that I need
    to enclose the "feeder" between the service entrance and the overcurrent
    protection device in conduit?

    This would make sense, since if that Romex wire got damaged somehow, and the
    hot wire shorted to ground, the only protection would be the main
    serice entrance overprotection device, which would be much higher in 
    ampacity than the capacity of the 10-3, which could result in a fire.

    Right?

>< Note 3604.17 by MFGMEM::S_JOHNSON >
>
>
>re .15, .16
>
>
>    So, what you're indicating to me is that this is okay, except that I need
>    to enclose the "feeder" between the service entrance and the overcurrent
>    protection device in conduit?

Use an "offset nipple" with bushing caps. Also make sure the feeder taps are
on their own lugs in the service panel.

>    This would make sense, since if that Romex wire got damaged somehow, and the
>    hot wire shorted to ground, the only protection would be the main
>    serice entrance overprotection device, which would be much higher in 
>    ampacity than the capacity of the 10-3, which could result in a fire.
>
>    Right?


That's one idea.

Does a subpanel in a different building need to maintain the separate neutral
and ground?  In other words, if I wish to add a breaker box fed with 220 in a
detached garage, do I need 3 or 4 conductor wire to feed it?

-Mike

    You feed the subpanel with 3-conductor wire; 2 hots and 1 neutral.
    The neutral bus bar is isolated ("floating") from the subpanel.
    You run a separate groundING lead from the ground bus bar in the
    subpanel to an earth ground (grounding rod).

RE:20 is correct. 3 wire, separate neutral and ground bus at the garage.
Also need a separate grounding electrode at the garage.
NEC 250-23 and 250-24 spell out the details:


250-23 states that A grounding connection shall not be made to any grounded
circuit conductor on the load side of the service disconnecting means.
(separate neutral and grounding bus)
And 250-24 states that two or more buildings supplied by a common service must
have an grounding electrode at each site.

Ross

Thanks.  At least I can use a piece of the 350' 3 conductor service cable I
have rather than having to buy more...

Doing it the way the code words it means the ground conductor of an auxillary
building is never connected to the neutral anywhere (except through the
ground itself), correct?

-Mike

    In that case, the only place the ground is connected to the neutral is
    at the service entrance of the main panel.
    
    Eric

>< Note 3604.22 by RAMBLR::MORONEY "How do you get this car out of second gear?" >
Mike, The intent of the code is to eliminate the effects of "ground loops".
This condition puts a potential voltage on the ground bus.

Ross

     Here's another NEC question:

     In income producing residential property -- an old house converted 
into a college dormitory -- are there any requirements about switches for 
private living areas being within those areas and not in public hallways?

    I also had a problem with humming noise from my track lights.
    Regardless of the setting of the dimmer, the bulbs themselves were
    making a very audible noise. I was using a $10 dimmer, Lutron or
    something, bought at Sommerville Lumber. I did what a previous reply
    suggested and bought another dimmer at a commercial electrical supply
    store. The humming was less but still there.
    
    I noticed that my recessed lights, using the same model dimmer, made no
    noise. They used a different type of bulb. So, I went and bought new bulbs,
    from a different manufacturer than my current bulbs and voula`, no
    humming on my track lights, even with my original dimmer!
    
    The bulbs were 75Watt R30 bulbs used in track lights. The original ones
    (the noisy ones) were bought at Light and Leisure (don't remember the
    brand), were I bought the track lights. The replacement bulbs were
    made by Sylvania (GTE) and cost the same.
    
    So, if replacing the dimmer doesn't work, try replacing the bulbs.

    Definitely the bulbs ..... we have 2 dimmer lights.  Both dimmers are
    identical, but the bulbs in the lights are different.  The one in the
    kitchen is a 'good' bulb (sylvania I think).  The one at the top of the
    upstairs is one of those 10 bulbs for $1.00 deals, and drives us a
    little nuts sometimes.  BUT, since it's at the top of the cathedral
    ceiling, it'll hum till it burns out.  I notice that it's a lot louder
    when the light is dimmest, and I can't hear it at all when the light is
    full bright.  Not sure what causes it .... I always thought it was the
    filament vibrating (don't know why I think that ....)

    
    It is the filament vibrating. I'm not sure whether this is related to
    the relative expense of the bulb, but a filament that has a shorter
    unsupported span will vibrate less. Some of the more ornate bulbs
    (clear glass or large globes) have very long, straight filaments and
    will absolutely sing.
    
    The dimmer works by chopping off the normally clean AC sine wave at
    varying point in each half-cycle - the earlier in the cycle, the less
    energy gets to the load. At full bright, the wave looks pretty normal,
    but at dim, it gets pretty spikey. My theory is that this causes
    either thermal shocks or an electromagnetic response in the filament.
    

    I've found a dimmer at Spag's that does not make the bulbs buzz at all
    (or I  have gone deaf).  It is styled like a regular light switch, with
    a small toggle,  rather  than  like  a  regular light dimmer with a big
    round knob.  I  can't  remember the brand name right now, but I'll look
    next time I go to Spag's. The price was $7 if I recall correctly.
    
    gjd
    

re: -.1

	You went deaf. :-)  I've got those switches and my very cheap .25/bulb
bulbs hum.

-Bob

    RE: -.1
    
    Do you really have the same part? 
    Power Controls # 143-131 Toggle Dimmer, $5.98 @ Spag's.
    
    The dimmer I had before, a leviton?, made the bulb buzz, but this one is
    quiet, and I have the same bulb in the lamp.

yup.  I found one still in the pack that I've not yet installed and that
is what it is, and that's what I installed in the house.  The humming 
won't keep you awake but is annoying if you're reading and yes I do buy
my bulbs when the cheap ones go on sale at 4/$1.

-Bob
          <<< Note 3217.14 by RUNAWY::QUEDOT::DVORAK "dtn 297-5386" >>>
                  -< It's possible, with the planer running >-
    RE: -.1
    
    Do you really have the same part? 
    Power Controls # 143-131 Toggle Dimmer, $5.98 @ Spag's.
    
    The dimmer I had before, a leviton?, made the bulb buzz, but this one is
    quiet, and I have the same bulb in the lamp.

    I had a cheap dimmer connected to my track lights when I lived in an
    apartment and it wasn't bad when turned up from about 75% to 100% full
    power, as far as buzzing goes, but anywhere under 75% or so and the
    dimmer hummed pretty loud.
    
    Question....(maybe stupid).... Once the dimmer is on are you using the
    same amount of energy when its low as when its turned up all the way?
    
    My assumption is that the brighter the lights are on the more energy it
    takes to get them that way.  i.e. if using a 100 watt light bulb with
    the dimmer half way up is it using only 50 or so watts?

                As you turn a dimmer down, the lights use less energy,
        but not as fast as you might think. Half brilliance is still
        about 2/3 (rough estimate) power consumption. BTW - a dimmer
        turn all th eway down but not OFF is still consuming
        electricity. It takes a bit of energy to ge the bulb hot enough
        so that you can see some light being given off.
                
                /s/     Bob

    Moreover, the lower you turn the dimmer, the less efficient the
    bulb becomes because of two factors ... first that as the light becomes
    dimmer, teh spectrum emitted becomes more red and effectively looks
    like less light .. and second that as a light is dimmed, its electrical
    resistance drops (it's a non-linear device).  So, a 100 watt bulb dimmed 
    to give the same amount of lumens as a 15 watt bulb will use significantly 
    more electricity than a 15 watt bulb.  And a 100 watt bulb dimmed to
    give the same amount of apparent light will use even more electricity.
    
    So, if you want a night light, a 5 watt bulb is a lot cheaper to use
    than a dimmed 60 ... on the other hand, the 5 watt bulbs do seem to
    burn out a lot more often with their ridiculous cost.
    
    Stuart
    

A while back, I was absolutely lambasted for suggesting  counter top
outlets be spaced no more than 24 inches apart. Well I'm finally taking
the electrical code update for 1990 and guess what? Article 210-52 (c)
Counter tops, has a change stating "Recepticles shall be installed so that no
point along the wall line is more than 24 inches", ...


FWIW, other significant changes: outlets in unfinished basements or crawl
spaces must be ground fault and washing machines in a bathroom must be on a 
ground fault circuit. If I come across any other important changes, I'll post 
them.


Ross

Just a nit:

24" apart <> "No point further than 24 inches"

No point further than 24 inches means that the outlets can be 48" apart, and
any point between them is no more than 24" from one or the other.

Pau

><<< Note 2966.32 by VMSDEV::PAULKM::WEISS "Trade freedom for security-lose both" >>>
>
>Just a nit:
>
>24" apart <> "No point further than 24 inches"
>
>No point further than 24 inches means that the outlets can be 48" apart, and
>any point between them is no more than 24" from one or the other.
>
>Pau

Correct, That's what the code requires as a minimum standard, but I still
favour even tighter spacing. Who knows, maybe in 1993 the code will require
even tighter requirements.

Ross

    I had a problem over the weekend with a dimmer switch and I was 
    hoping that someone out there could help me out.  I installed a
    new bedroom light which was controlled by a dimmer switch.  The
    light I installed held 3 (75 watt max.) bulbs in which I used
    Sylvania halogen bulbs (these are made to replace incandescents).
    I changed the light, but as I turned on the dimmer, I immediately
    heard a loud pop from the dimmer.  Needless to say, the lights never
    went on.
    
    Is the problem in the dimmer switch, or in the light?  I heard
    (after the incident) that halogen lights should never be used
    with dimmer switches.  Is this true?
    
    /Tony
    

I'm aware that the Sylvania halogens say don't use them with dimmers, but
I've got five of them running off a Lightolier dimmer in my kitchen and
they've never given me a problem.  You may just have a defective dimmer.

			Steve

BTW, if you plan on running the bulbs at a low level, you'll seriously
reduce the life of the halogen bulbs.

			Steve

    I don't have a choice of a dimmer.  After the loud pop, there
    was no electricity going to the light.  I'm wondering whether
    I have a bad light (short) or bad dimmer.  Any thoughts?

I'd suspect the dimmer first.

	Steve

Also check all of the wiring around the dimmer.  When we were doing our
living room, we had a problem with some bare wiring touching the metal
box and blowing the dimmer switch.  Tightened wiring (fixed insulation
problem) helped solve the problem.

Ed..

I recently tried to install a speed controller on a ceiling fan.  I bought a 
wall mount dimmer (speed controller) at Somerville that explicitly said "for 
ceiling fans".  However, upon installing it, I get a noticable HUM from the fan.
I got the fan from BJ's, I believe the brand is Northern.  (It does contain this
warning:  "To avoid the possibility of electrical shock, do not use this unit 
with a solid state dimmer."

For now, I replaced the dimmer with an on off switch, and attached a long chain
to the fan to use it's built in 3 speed switch.  But I would like to control the
speed with the dimmer on the wall.  It's gotta be possible, I've seen other 
installations.

    
    The motor has to be set up for it. I believe your's isn't. I have a fan
    on my wood stove that's the same way. I'd love to put it on a 2 speed
    switch, but can't.
    
    Mike

    re .25 
    
    Just curious.  What speed did you leave the fan on when you tried the
    dimmer?  The fastest speed I presume?  Did you try the middle speed?
    
    again just curious,
    Steve

I tried all 3 speeds.  High speed made the most hum.  Low speed the least, but
it doesn't go fast enough.  All speed made an audible hum.

Is there any way of telling what kind of motor it is.  There is no indication
in the papers.  Let me put it a different way:  What kind of motor works with a
dimmer, and what kind does not?

A correction, by the way, the brand is Northman.

re: .27, .28

About 6 years ago I installed a ceiling fan and was warned of the humming by
the retailer who sold me the setup.  After installation, it did hum on all
settings (variable speed control), but not to any great degree.

Today, there's so little hum, that I can't say I hear it.  That could be for
one or more of the following reasons:

1. I'm getting older and my hearing just ain't what it usta be.

2. Whatever was humming in the motor got all hummed out or has gotten stuck
   somehow.

3. It's still humming at the same intensity, but, I'm getting older and I
   just don't care.

Some other considerations also... the fan's in the family room and I've got
three kids, 7, 5 and 2.  They are quite adept at making high level humming noises
themselves.  The TV's in there and, because of the kid-noise, is running at a fair
dB level itself.  Maybe if I slept in there, I'd find the humming intolerable.

Chris

    I have the same problem described in .25
    
    I bought a Casablanca fan which my electrician said was a very high
    quality brand. I also installed a light on the fan so I am using a dual
    dimmer switch, one for the light and one for the fan.
    
    I noticed the humming also. The humming is at its loudest when the
    dimmer is at its lowest setting. I also noticed that when the fan pull
    chain is used to select the lowest speed, and the dimmer is moved to
    the lowest setting, the fan seems to run *faster*. This doesn't seem to
    happen, or at least, be as noticable at the higher speed settings.
    
    	In any event the dimmer only seems to control the fan speed
    *within* the setting on the fan itself. The fan has three speeds, when
    it is on the lowest speed I can use the dimmer to select various speeds
    all in the low range. At high speed I can lower the speed with the
    dimmer somewhat but not lower than the middle speed.
    
    	All in all I like the dimmer for the light but for the fan is
    wasn't worth it.
    
    
    
    

    I also experience the hummmmmmmmmm with the dimmer/fan combo.
    I figured I needed a motor speed control and not a standard
    incondecent light dimmer control.
    
    Has anyone gone the motor speed control route and eliminated the hum?
    
    Dave'
    

	Ref .31

	I just went through all this. I first started off with the variable 
control "fan" switch and got the hum at low speed. My son the electrician 
purchased a three speed switch for the fan. It had an OFF, HI, MED, and LO on 
the dial. It clicked at each setting. It too hummed! I gave up and put the 
toggle switch back on and it eliminated the humming. All of the above switches 
were for fans, not lights.

Mike 
    

Some motors can be used with speed controls, some can't.  I don't know what
it is about the design that differs.

			Steve

    Typically, fans are driven by shaded pole motors (oversized record
    player motors) ... the motor, unloaded, will operate at a fixed
    speed depending on the number of poles.  In a fan application,
    the motor slips under load.  One way of controlling the speed is
    to control the power applied to the motor field windings.  When
    insufficiently powered, the amount of slip increases dramatically
    and hence lower speeds.  Another way is to essentially change the
    number of poles by applying power to more windings ... the more poles
    the faster the motor.
    
    The problem with speed control via a dimmer is that the shaded poles
    are in essence "tuned" for low frequency operation.  A typical dimmer 
    introduces a strong 120 Hz harmonic component into the power feed
    which will cause a vibration that you hear as hum.
    
    There are some types of motor that will work with this kind of speed
    control, but the shaded pole motor is not one of them.
    
    Universal motors as used in drills etc are best for this kind of dimmer
    speed control.
    

    You can vary the speed of an induction or shaded pole motor by
    varying the frequency of the AC voltage from something other
    than 60HZ, but that requires a fairly elaborate circuit to pull
    off.  Basically, you have to change it to DC then fake it back
    to a pseudo-AC at the desired frequency.

    But Steve, you'd never get the required amount of circuitry in a
    switch box!  And when you rstore it to pseudo AC, it shouldn't be
    a wafefor with a high 2nd or 3rd harmonic ... otherwise you'll hear
    HUMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM! :-)
    
    Stuart

    Right, it's totally impractical for this application.  It's used in
    industrial applications to control the speed of machinery that's
    driven by induction motors.  Warner Electric makes a nice solid-state
    unit to control 3-phase motors up to 1hp, I believe it is...a mere 
    $500 or so.
    

    And in general, in those applcations, it would be rare for anyone to
    care about a little extra hum from the motor!

	   Back when I worked in an electical supply store, the Casablanca
	fans had a very high return rate.  Something on the order of half!
	They may have been improved upon since then but you'll never con-
	vince me of that.  IMHO, I'd go with Hunter for best quality and
	quietest operation.  I bought their bottom of the line and it's
	very quiet (a priority for me).
	   As for speed control, I've never had a problem with the three
	speeds hard wired into the fan from the factory.  If low speed
	isn't slow enough, you probably don't need to be running a fan.
	BTW, even dimmer controls make noise.  Light bulbs don't resonate 
	the vibration as well as a big paddle fan so it's not nearly as 
	noticable.
 
					Tim

The fan is totally quiet, when it's running on a switch.  I was hoping to be 
able to get speed control from the wall switch, rather than having a 4' long 
chain hanging down in the middle of the porch, which is what I have now.  On a
dimmer, the fan hum is loud enough to be heard over the stereo (which we don't
play too loud, but...).

    I don't know if this will work with your fan, but NuTone sells a three
    or four speed wall switch which seems to work fine without any buzzing. 
    We have two of their fans, and each one has one of these and there is
    no hum on any of the settings.  I don't know how the internals of the
    switch are wired, but maybe they have balanced the frequencies at
    specific speeds so you don't hear it?
    
    In any case, try it, and if it doesn't work, take it back.
    
    It may be it's designed to work only with NuTone fans.
    
    /greg
    

    OK, what am I missing here??  I read this whole note, and didn't really
    see that the initial question was answered!  I have a dimmer with two
    wires coming out of it that I want to install in a PLASTIC box with
    three wires coming into it (neutral, power and ground).  Although the
    front of the dimmer is all metal, there is no place to attach a ground
    screw.  Is it legal to just not ground the dimmer, put a wire nut on 
    the ground wire coming into the box, and call it a day?  Or do I need
    a different dimmer (one with a ground connection).  Thanks in advance,

					Peter

The metal plate is a heat sink - most dimmers (and indeed many switches)
aren't intended to be grounded.  Just cap the ground wire.

			Steve

    Wouldn't it be correct to attach the ground wire to the metal box with
    a grounding screw? That would make the dimmmer switch grounded since it
    would be attached to the metal box with screws.
    
    Thats' what I would do. 
    
    (the other) Steve 

    .14 is perfect if you're using a metal box, but not with a plastic box.
    
    If the coverplate depth will allow it, I usually wrap the ground wire
    around a mounting screw and trap it between the device and the box..
    
    ...tom

>>    If the coverplate depth will allow it, I usually wrap the ground wire
>>    around a mounting screw and trap it between the device and the box..

This is, of course, not a legal ground (but you don't really need one).  The
method used to ground a device can ONLY be used for grounding - if its used for
something else (for example to hold something in place) - its against code.  

A common example of this I used to see is homeowners wrapping the ground wire
around the same screw that was clamping the RX wire in the box - and of course
cutting the extra so there is no way to get a good ground anymore...

bjm

The metal box is not necessarily grounded - my house is mostly wired with
14/2 wire and no ground, the metal boxes are just boxes.

				Steve

    On a related note, what's the deal with light fixture mounting straps?
    All the light fixture boxes in my house connect the incoming ground to the
    metal box, and have a pigtail available for connecting to the fixture.
    Is it legal to just connect the pigtail to the light fixture, and not 
    bother grounding the mounting strap?  If not, and both the strap and the
    light fixture have to be grounded, is it legal to simply screw both the
    pigtail AND the ground from the fixture under the mounting strap ground
    screw?  Or do I have to create two pigtails, one for the strap and one for
    the light fixture?

    Also, interestingly enough, I've found that I don't need a mounting strap
    with most of my fixtures, since the screws in the fixtures lined up
    nicely with the holes in the box itself.  Or did I violate an obscure
    section of the code by omitting the strap...!?

    Thanks,

				Peter

    Does anybody have the answers to those questions?  (If they were really
    stupid questions, please let me know too!  Any info. would be helpful,
    since I'm replacing every fixture in the house).  Thanks.

I don't think the strap is required, but I think you're supposed to attach
a ground wire to the box somehow.  Some boxes have screws for that purpose.

				Steve

I belive there are some silly rules (may actually be local, but they may also
come from the rule about the method of grounding can not be used for anything
else) about when the fixture is NOT mounted, it still needs to be grounded -
that is, if for some strange reason the screws holding the fixture onto the box
let go, the fixture would be haning in the air, still grounded via the ground
wire to the ground screw on the mounting strap and then to the grounding wire
that is part of the house wiring.

If you are not using a mounting bracket and the fixture has a ground wire for
it, you should connect it to the house ground - somehow - usually via a wire
nut.

I do NOT think the code gets into mounting methods of various fixtures - just
into the flow (or potental flow) of electrical current.  It most likly has
details about "when this mounting method is used, a seperate ground must be
required" - but I don't think details of ceiling fixtures would covered.  
   (disclaimer - its been several years since I've even held a NEC book, 
    never mind read one).

bjm

Yes, cheap switches.  I have some which also do this.  Replace them with
"Spec grade" switches - will cost a buck or so, rather than 49 cents.

				Steve

    do they say "Spec grade" on the package?

Yes they do, and on the switch itself (stamped on the metal or on the switch
housing).

				Steve

    We just recently had granite countertops installed.  At the same time,
    we had the same (3/8 inch think) granite placed on the walls as a
    splash.
    
    The problem is that when we went to put back our switchplates and plug
    covers, the screw isn't long enough to reach all the way back to where
    the electrical hardware is (now that the switchplates are 3/8 inch
    farther forward).
    
    Is there an easy way of moving the electrical hardware forward by 3/8
    inch?

No easy way to move the boxes forward - if they were put in as new-work, they
are nailed to studs and won't move :-)

You can get longer screws - you want screws with an 8/32 thread.

But the other issue is "covering" that 3/8 of an inch.  I think the code has
something in it about devices (ie the outlets) should be mounted "in" the
boxes, when you have them hanging out 3/8 of an inch, you don't meet that
requirement.  But of course, its done all the time.

If you want to cover the area, the best was I've heard described it taking a
new plastic outlet box, cutting 3/8 of an inch off the front and use that as an
extention to the recessed box.

bjm

I have seen devices for this:  A shallow box with no top or bottom that's
placed over the existing box and screws into it where the device would. 
The outlet/switch/whatever screws into this box.  No idea what they're called.

    They're called box extenders, and you can find them at Home Depot, etc.
    
    			Steve

Hmm - they make them now huh?  The only ones I have seen for sale were metal
and for either 4" square boxes or handy-boxes (the single-gang metal box on the 
side of your furnace is a handy-box - at least that is what they were called
'in the trade' 10+ years ago).

bjm