I am finishing my basement and need some tips on how to do a few things for
rough in. I am in Gwinnett County, GA if that matters.
1) I definitely will have some sort of drop ceiling, probably acoustic tile but
there is a small possibility it may be sheet rock. The ceiling will drop about
a foot or so from the bottom of the joists.
a) I assume that any electrical runs to lighting in the ceiling (cans, etc)
will require armored cable since the wire is unsupported/unprotected from the
joist to the tile?
b) I also assume that this means I will need to terminate the NMB cable into
a metal junction box, and run the armored cable from there to the fixtures?
c) for rough-in there will be no actual fixtures...so how do I terminate the
armored cable? Or do I not run any armored cable at all until fixtures are
2) What is used to rough-in wall lights (for example the bathroom), a standard
circular fixture box like they used for the ceiling?
3) Will the inspector examine only what I have done? ie if he/she sees
something that is sloppy but was done by the home builder, could I be required
to fix it? That would seem rather unfair since THEY were supposed to get it
inspected to get the CO...
Save yourself at lot of worry. Formalize your intentions and try to meet
with the inspector at his office before you start work. Explain what you
plan to do and ask if that is correct for your area. I have never found any
inspector unwilling to work with a homeowner who cares enough to want to do
Why do you want to drop the ceiling?
Now to try and answer a few of your questions. These answers are based on
this locale. Each area has their own little quirks even though they all use
the same code.
1. There can be no junction boxes concealed above a drywall ceiling. All
junction boxes must be accessible. I don't know about armored for the one
foot drop. I do know that nm can not run across a metal grid for a dropped
ceiling. In a normal situation without the drop NM is run to each can
2. yes or possibly a switch box it depends on the fixture. For some fixtures
you just have the wire there for the rough in and make the final connection
inside the fixture.
3. Normally yes
Because I have to. Duct work, gas lines, water lines etc run all
across under the joists.
I had thought about this because I knew junction boxes could not be
enclosed. I guess the only way to do this correctly (ie dropped
drywall) is to run armored cable everywhere? I don't know how I could
do that logistically, and it would require significant rework.
Most drop-in fixtures (cans, flourescents, etc.) have a builtin box
or box-like connectors so that the junction is made inside the
fixture (i.e. armored to first can - wired to first can and armored
to second can. Armored to second can wired to second can and
armored to third can.) You would just run NMB to each light
locations and leave an extra two or three feet of wire in a loop
there. Then when installing the fixture, cut the loop, make the
connections inside the fixture, finish the install, and go to the
next. If you are not sure about wanting a light at a specific
location, leave a loop anyway. Too many DYIers worry about
'wasting' wire and wind up not leaving enough to make a proper
connection. In the total cost of the project, NMB is cheap.
1) In order to add enough circuits in my breaker box, I may have to double up
some of the breakers. We had a new heat pump system installed and the HVAC guys
stole a lot of space!
I really only have one breaker space left, and 2 more circuits to run (1 20A for
bathroom and 2 15A for bedrooms), BUT some of the other breakers are single and
could potentially be converted to two small breakers. What are the rules
regarding this? I am wondering why some are single and some are double...why
not just make all of them double to leave space?
2) Does the bathroom circuit have to be dedicated to the GFCI outlet ONLY or can
it also feed the vanity lights?
3) Can NM cable be run diagonally under the joists, or must it follow the inside
of the joist or through holes? (remember I will be doing a drop ceiling)
When you buy a box, its listed max capaciy usually is with double breakers.
In most later model boxes, a double breaker will be fed by one phase of the
240V. In some older boxes the double breaker might actually be fed by both
phases (as if they were seperate breakers). This differentiation really
only becomes important if you are using 3 conductor romex and trying to use
one neutral for two hot branches. In that case, the two branches should be
fed by different phases in the breaker box. If all your branch circuits are
wired on 12-2 romex, you probably don't have to worry about which phase you
are connecting to.
Run 20A to the bedroom unless the wire is 14# If you have 12# wire give it
all the juice it deserves. In many areas, AFCI breakers are required for
bedrooms. These usually only come in full slot size (no doubles). AFCI are
not available in receptacles like GFCI and must be in the box. Check your
city to know if it is required. I like GFCI in the bedroom also.
If you trip the breaker, you'll be fishing around in the dark looking for
the reset. Not sure of the code on that one. Can wire the light to the
bedroom lighting ckt. If the fixture has a plug, it should be GFCI also.
If the joists are in an inaccessable area not likely to be touched or
stepped on, it would be OK. If the cieling is suspended in such a way that
one could not put a nail through a cable it should be OK. Concieling the
wire is a better practice. Check with your city, they might want you to use
armored cable in that situation.
The little "Code Check Electrical" book is a very concise resource
containing all the answers you seek and can be purchased at most big box
if you use the tiles instead of the sheet rock to drop the ceiling then
you will be able to access the junction boxes as well as the ducts and
pipes and all the other things that may need service up there.....
Your box will indicate somewhere what its max circuit capacity is; this
will probably permit some but not all of the breakers to be doubles.
For example, if the box has 50 slots it may permit 60 circuits, so 10
of the breakers can be doubles. Be aware that you may need to add extra
neutral (and less probably, extra ground) bus bars; unless the panel
says so explicitly, don't try to put more than one neutral wire under
one neutral bus screw. I *think* you can usually double up the ground
wires but I'm not certain. On this topic code says to do only what your
panel's manufacturer says is ok.
I've heard the answer to that and I forget it, partly because Canadian
and US codes are different on that question. Search other postings in
this NG and you'll find it.
In general NM should be along the faces of joists and through holes,
never across the undersides of them. At your ceiling-mounted light
fixtures (octagonal boxes or recessed pot lights) you staple the NM to
the nearest joist and then it can run to the box; there should be no
need for armored cable unless your local code requires it (as I'm told
Chicago, NYC and some others do).
You *might* get away with stapling the NM to boards that are fastened
across the undersides of the joists; this is permitted in certain
circumstances where you're sure there will never be drywall on the
joists. I think it's the inspector's call.
I'm wondering how you'd do a dropped drywall ceiling. I guess you'd
have to build a whole framework of joists at the height you wanted it.
Of course you can never have any electrical junction box hidden insde a
drywall ceiling; there are metal access panels you can build into the
ceiling if you have to. If you plan to avoid junction boxes by making
your connections in the pot lights, ie feeding one pot light from
another, be aware that the little boxes on pot lights may be used as
junction boxes only if they're marked as such. Some are, some aren't. I
think it's a matter of how big they are.
Long answer from another current thread:
UL, as I understand it, in their standard for panels limits the number
of 'poles' that can be installed in a panel. (a 220V breaker is 2 poles,
a 12V breaker is 1 pole, a 120V tandem breaker is 2 poles.) The maximum
number of poles in a 100A 120/240V panel is 20. (In a 200A panel 40.) If
a panel has positions for 16 full sized poles it could have 4 more poles
and stay under the 20 limit. These can be installed as 4 120V tandem
breakers. To prevent more than 4 tandem breakers from being installed, a
tandem breaker has a hook to install it on the panel rail instead of the
normal SquareD U shaped clips. Only 4 positions on the rail can have a
slot to accept the hook. These breakers are called class CTL (circuit
limiting). (A 100A panel may be designed so fewer than 20 total poles
can be installed.) Previous to the class CTL panels tandem breakers had
the normal U shaped clip and could be installed in any position (or all
the positions). Last I heard these non-CTL breakers were still
available. As indicated in the quoted post, a panel on its label should
have a list of breakers that can be installed in that panel. A class CTL
panel will not have non-CTL breakers on the list and it is a code
violation to install a breaker that is not on the list.
From aother current thread:
NEC 2002: 408.21 allows only one neutral per lug.
"Explicitly" is right.
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