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Conference 7.286::home_work

Title:Home_work
Notice:Check Directory (6.3) before writing a new note
Moderator:CSLALL::NASEAM::READIO
Created:Tue Nov 05 1991
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2100
Total number of notes:78741

286.0. "Wiring, Metal vs. Plastic Boxes" by BCSE::JAHNS (Dean Jahns ZK03-2X07 DTN 381-0739) Tue Jul 26 1988 23:05

Well, I've been looking at the notes concerning wiring ,fans and switches.
I've answered alot of my questions already, but still have a few.

I just installed a whole house fan.  Everything seems to be working, 
properly, at least no breakers blew.  The fan includes a variable speed 
speed control.  Since I was not able to wire the control "in line", I 
followed the instructions in on of my books, running a wire down thru 
the wall to the control and connecting the black and white wires to the 
two black wires on the controller, after wrapping black tape around the 
end of white wire.  

Question #1 :  		While doing this I noticed a detail 
that had escaped my first reading of the fan instructions; it called 
for a metal box to hold the controller and I had bought a plastic box.  
Should this be a problem?  Since there is no green terminal on the control,
does it rely on being attaced to a grounded metal box.  If using a plastic
box is OK here, what do I attach the ground wire that came down to the box
with my (now) 2 black wires.  Below is a drawing of what I did.

               	       New junction box  
				   in attic
        	 black        |================|
existing	---------------------------o---------------->
circuit          white        |            |   |               on to existing
(14-2)		-------------------o-------|---------------->   outlet
                 ground       |    |       |   |               (14-2)
		----------------------o----|---------------->
                              |=== |  |\   | ==|
                                   |  ||   |
                                   |  ||   |     new wiring |
                                   |  ||   |      (12-2)    V
                                   |  ||   |
      white                        |  ||   |
     ------------------------------|  ||   |
      ground                          ||   |
     ---------------------------------||   |
FAN   black                            |   |
     ------|heat switch|------------|  |   |
                                    |  |   |
                              black |  |g  | white(now marked
                                    |  |   |       black)
                                    |  |   |
                                    o  V   o
                             black  | ?#1  | black
				    |      |
				  ==============
       			          variable speed
			              control
                                  in plastic box



Question #2:  Although I've seen it referenced a few times, no one seemed to
explicitly put the issue to rest of whether the fact that I have extended
the existing  14-2 wiring with 12-2 cable for my wiring, is within code. 
The circuit is still protected by 15 AMP breaker.  However, a friend said
an inspector had made him rewire in the same situation.

Question #3: How necessary is it to twist before using wire nuts?

As I said, it seemed to work fine last night, but I left the breaker off 
today just in case anyone here spots a screaming no-no!  I never tried to
do a wiring schematic on a vt220 before, lots of fun, hope it makes sense!

Thanks,

-dj-
    
T.RTitleUserPersonal
Name
DateLines
286.9I like Plastic!TRACTR::DOWNSTue Dec 08 1987 10:249
    I like the plastic, but do perfer the metal in areas like a workshop,
    because they are probably out in the open where they can get hit
    by something. When I wired my house I used all plastic with no ill
     effects. Most new construction I've seen use plastic. Another plus
    about plastic is that a wire cannot short out against the box (plastic
    is a non-conductor while metal is). As a result, you don't have
    to worry about grounding the box. I'd choose plastic under most
    conditions!
    
286.10What type of plasticLDP::BURKHARTTue Dec 08 1987 12:5615
286.11another person for plasticPSTJTT::TABERAlimentary, my dear WatsonTue Dec 08 1987 13:1410
The electrician just finished rough wiring in the area of my house 
that's being renovated.  I was a little surprised to see that he put in
plastic boxes, but they're not like the cheapie plastic boxes that I've
found in stores.  (Or used myself.) These are hard like phenolic. 
There's no chance that the three-switch box is going to lozenge. 

Like others, I've had no problems with the plastic boxes, and even 
prefer to use them when they're going to be covered up.

					>>>==>PStJTT
286.12SMURF::DIBBLED&H Travel AgentTue Dec 08 1987 18:173
    I found that installing a plastic box in an existing wall was pretty
    easy. You just cut the hole, and use a couple of sheetrock screws
    to fasten it to the 2x4.
286.13SCOMAN::RUDMANLet me tell you about my dormer...Tue Dec 08 1987 19:176
    The electrician ("Bob") used yellow plastic boxes which were firm
    but a little flexible, fastened to the stud by one angled 16D (or
    20D).  I thought they were quite sturdy.  After the plasterer was 
    done there didn't seem to be any difference...
    
    						Don
286.14where to get them?NETMAN::SEGERthis space intentionally left blankWed Dec 09 1987 16:254
So now the question that remains is what quality are the ones at SPAGS?  Are
there better places to get them?

-mark
286.1some commentsREGENT::GETTYSBob Gettys N1BRM 223-6897Wed Jul 27 1988 01:1911
                I have always been of the understanding that extending a
        15amp circuit with 12 guage wire was not correct. However, there
        are times when a 15amp circuit MUST be run with 12 guage wire if
        the run is longer than a certain length. Can someone quote the
        code here??
                
                The metal box is probably for added heat sinking. Speed
        controls often get warm (some might be called hot) when used. If
        it calls for a metal box, it probably requires one.
                
                /s/     Bob
286.2I may be overreacting, but...ARCHER::FOXWed Jul 27 1988 02:048
    What type of speed control do you have? I just installed my WHF,
    and used one made by Broan (same manu as the fan). It has some
    good size fins the extend out from the wall - not the prettiest
    piece of wall decor, but effective in dispersing heat. I'd rather
    have that taking place outside of the wall as opposed to using
    the box to do it.
    
    John
286.312g ok for 15ampCADSE::MCCARTHYI fixed it yesterdayWed Jul 27 1988 10:228
    RE:.1
    	I do not think it is against the code to use 12 guage wire for
    a 15 amp curcit, its when you put a 20 AMP fuse on a 15 AMP wire
    that is a no-no.  12 Gauge is harder to work with (in boxes/devices).
    
    	I would agree that it would be smart to use a metal box.
    
    bjm
286.4More opinionVIDEO::DCLDavid LarrickWed Jul 27 1988 12:0822
We're all still waiting for somebody to quote the Code, rather than just 
give an opinion.  But since my Code book isn't handy, here's _my_ opinion:

#12 wire on a 15A circuit is fine, and indeed required for long runs. 
Using #12 for a short run also allows you to upgrade to a 20A circuit later 
if your needs change - _if_ that circuit is _all_ #12.  If it has a stretch 
of #14, you're stuck with 15A forever (with a few exceptions specifically 
called out in the Code).

I suspect that the inspector in .0 objected to an instance of apparently
random mixing of #12 and #14, not to the general concept of using #12 on a
15A circuit.  I can see his point; seeing #12 and #14 mixed on a circuit
for no good reason wouldn't give me a lot of confidence in the rest of the
installation.  So I think the inspector was enforcing consistent, workmanlike 
practice rather than Code in this case. 

If you have a good reason for mixing #12 and #14, go to it, but be prepared 
to recite that reason.  A couple of those reasons are given above.  Another 
is that you plan to switch the whole-house fan over to another, 20A circuit 
later.

"I ran out of #14 and had plenty of #12 around" probably isn't a good reason.
286.5...still wary...BCSE::JAHNSDean Jahns ZK03-2X07 DTN 381-0739Wed Jul 27 1988 13:1320
    re: .2  
    
    	The speed control switch was included with the Sears fan, as
    well as the heat switch.  Yes, it extends from the wall and is ugly,
    especially so since I mounted it very high to be out of reach of
    children.
    
    re: .4
    
    	My thought is to one day run a dedicated circuit to the fan,
    all 12 gauge, since it is a BIG fan.  But I thought I'd wait until
    I finish my basement when I probably bring in an electrician to
    do the main box work.
                         
    The wiring plan must be OK then?  You can read as much as you like,
    but us first timers are still a little skitterish, ya know.
    
    -dj-
    
    
286.6use a B-I-G boxLITLTN::CAHILLJim CahillWed Jul 27 1988 14:2525
    One thing you should check is the junction box you used to tap into
    the existing circuit.  You now have at least six 14-gauge wires, three
    12-guage wires, and three wirenuts (not counting the possible three
    mounting devices to attach the cables to the box and a grounding strap
    for the box itself).  All the above are included in the formula which
    the code uses to determine the maximum capacity of a junction box.
    Is your box big enough to satisfy this part of the code?
    
    To answer your third question, normally you do not twist the wires
    together before putting on the wire nut.  Just make sure the insulation
    is trimmed to the proper length on all wires to be joined, and the
    stripped lengths are also the same.  Hold the wire ends together and
    twist on the wire nut, letting the twisting action pull the nut onto
    the wires.  When done properly, no bare wire should be exposed.  If
    any is, I usually just wrap electrical tape around the wire nut to
    cover it up, but this probably isn't the "right thing to do".  (I'm
    just too lazy to take the nut off and retrim the wires, I guess!)
    
    The one other thing no one else has yet mentioned is the answer to
    the question about what to do with the ground wire that comes into
    the controller switch box.  Given the answer is to switch to a metal
    box, that ground wire should be attached via a little jumper wire to
    a screw fastened into the box.  This will not only ground the box,
    but the speed controller as well, through its mounting screws.
    
286.15Boxes for exterior outletTOKLAS::FELDMANWeek 3: Raising the RoofFri Jul 14 1989 00:5314
    What type of box should be used for outlets mounted on the exterior of
    the house, where the box is inside the wall.  Obviously weatherproof
    boxes and wiring needs to be used for outlets that are removed from the
    house (e. g. at the far end of a large patio), and all outlets I've
    ever seen mounted on a house used the weatherproof flip-up outlet
    covers, but I'm not sure what type of box to use.  I suppose I could
    remove the cover from our existing outlets, to see what's there, but
    that assumes they were done correctly -- an assumption I'm never
    willing to make.
    
    Also, are special outlets required, or is it just the cover and perhaps
    box that needs to be special?
    
       Gary
286.16standard box, special cover.REMEDY::KOPECnow I try to be amusedFri Jul 14 1989 11:348
    A standard box is fine. Outdoor outlets should (must?) be on an
    Ground Fault Interrupter. 
    
    The only special part is the cover, unless you want something that
    is weather-tight when something is plugged in.. then you get a whole
    box that mounts outside the house, etc etc...
    
    ...tom
286.7Ganging up on plasticGIAMEM::RIDGEMon Mar 05 1990 11:569
    I need to add a single box to an existing box. The existing box is
    plastic. I have done this with the metal boxes but never had to do this
    with a plastic box. How do you do this when there is a plastic box that
    you need to double up on?  
    BTW the box currently holds a wall switch and I would like to add a 
    switch for a ceiling fan. No problem with the instalation except for 
    this. I would like to have a double box where there is a single.
    
    Steve
286.8Replace entire boxVINO::DZIEDZICMon Mar 05 1990 12:149
    You don't double up the existing box - you break it apart, remove
    the pieces and mounting nails, then use a double box designed for
    renovation work.  FWIW, The Family Handyman had a short blurb on
    this in a recent (past 4 months?) issue.
    
    Of course, you COULD simply use one of the double switch units
    which are two switches stacked vertically; the cover plate is
    identical to a standard duplex outlet.  This might save some
    trouble installing a new box; may not "look" as good.
286.17Fiberglass revisitedSTAR::DZIEDZICThu Feb 21 1991 13:168
    My personal preference would be the tan fiberglass moulded boxes
    manufactured by Allied Moulded; M&M Electrical in Nashua, NH
    carries these.  They are VERY sturdy and stand up to accidental
    hammer blows and seem to survive the router bits used to cut
    out drywall openings better than PVC.
    
    These boxes are also 2 hour fire rated, if you care about that
    sort of thing.