On Tue, 23 Aug 2011 10:27:04 -0400, "Mike Marlow"
wrote:

Bill wrote:


I was thinking in terms of the "wire space" of the box (as in how many
wires can be in there, not how much wire can I pack in there). As you
know, most/all electrical boxes have their cubic inches written
inside. I'll have to get out my chart to do the calculation.

If you feel you must...

Bill is our token _serious_ AR guy here. Of course he must.

But I think the NEC wants him to mess up his ceiling further, with
individual races for each of 3 circuits. I wonder if he'd get dinged
for running the extra 2 through two of the center light fixtures...

--
It is characteristic of all deep human problems that they are
not to be approached without some humor and some bewilderment.
-- Freeman Dyson

Larry Jaques writes:
On Mon, 22 Aug 2011 18:47:55 -0400, Bill
wrote:

Larry Jaques wrote:
On Mon, 22 Aug 2011 04:17:46 -0400,
wrote:

Larry Jaques wrote:

Ceiling box surface mounted with fmt to in-wall box might be my
choice. Romex in wall, stapled to stud. http://goo.gl/UYFER


You would be using all of the fixtures as "electrical boxes", correct?

So, if I understand your design correctly, I wouldn't need any more
boxes other than the "switchbox".

Correctamundo. There are usually lots of knockouts in fluor fixture
bases for connecting EMT fittings. Use those for runs for all three
switches. Check the NEC for congestion. I think 3 pairs will be OK in
1/2" EMT with a single larger ground, but check.

Yes, there are *lots* of knockouts on the fixture bases. I need to
check the "wire space" of the fixture bases and of other pertinent
specifications. If the fixture bases aren't large enough that will
create mucho extra work.

I've never seen a fluor box which didn't have ample space for wiring.
Mine are for T-12s, so there's room for about 150 extra 14ga THHNs in
each.

--- Begin Quote ---

Section 410-31 of the NEC (1999 Edition) states:

Fixtures shall not be used as a raceway for circuit conductors.

Exception #1: Fixtures listed for use as a raceway
Exception #2: Fixtures designed for end-to-end assembly to
form a continuous raceway or fixtures connected
together by recognized wiring methods shall be permitted
to carry through conductors of a 2-wire or multiwire
branch circuit supplying the fixtures.
Exception #3: One additional 2-wire branch circuit separately supplying
one or more of the connected fixtures described in exception
#2 shall be permitted to be carried through the fixtures.

Branch-circuit conductors within 3 inches of a ballast within the ballast
compartment shall have an insulation temperature rating not lower than
90 degrees C such as Types RHH, THW, THHN, THHW, FEP, FEPB, SA and XHHW.

--- End Quote ---

Most consumer grade flourescents aren't listed as raceways. That pretty
much leaves exception #2 as the guidance for this application. It also limits
you to 2 two-wire or 1 three-wire and 1 two-wire branch circuits for the
string of fixtures.

Do note the "recognized wiring methods".

Please also be aware that the temperature rating of the conductors being
passed through must be at least 90c (THHN should suffice, but never use NM or NM-B)

scott

On 8/23/2011 11:02 AM, m II wrote:
It would be a little ridiculous to worry about the little protection EMT
provides over Romex when you have surface mounted lighting fixtures
exposed to bashing with lumber. Things need to match and not get
ridiculous. Like Mike says...put Romex in the ceiling and forget all the
fuss. A little surface exposure is not a big deal. If you listened to
Dougy you won't be getting an inspection anyway.

What on earth are you talking about? I never recommended omitting an
inspection.

Scott Lurndal wrote:

--- Begin Quote ---

Section 410-31 of the NEC (1999 Edition) states:

Fixtures shall not be used as a raceway for circuit conductors.

Exception #1: Fixtures listed for use as a raceway
Exception #2: Fixtures designed for end-to-end assembly to
form a continuous raceway or fixtures connected
together by recognized wiring methods shall be permitted
to carry through conductors of a 2-wire or multiwire
branch circuit supplying the fixtures.
Exception #3: One additional 2-wire branch circuit separately supplying
one or more of the connected fixtures described in exception
#2 shall be permitted to be carried through the fixtures.

Branch-circuit conductors within 3 inches of a ballast within the ballast
compartment shall have an insulation temperature rating not lower than
90 degrees C such as Types RHH, THW, THHN, THHW, FEP, FEPB, SA and XHHW.

--- End Quote ---

Most consumer grade flourescents aren't listed as raceways. That pretty
much leaves exception #2 as the guidance for this application. It also limits
you to 2 two-wire or 1 three-wire and 1 two-wire branch circuits for the
string of fixtures.


Scott.

There is only 1 15A branch circuit. However, I had planned for it to
"split" through 3 switches in the switchbox and pass the resultant 5
wires--3 hot, 1 neutral, 1 ground, through the fixtures as necessary to
power them. If I understand correctly, this would qualify as a single
2-wire branch circuit, wouldn't it?

TYVM!
Bill


Do note the "recognized wiring methods".

Please also be aware that the temperature rating of the conductors being
passed through must be at least 90c (THHN should suffice, but never use NM or NM-B)

scott

Mike Marlow wrote:

That's not what I was referring to Bill. I was talking about all of the
fuss (if I understood it correctly) with hitting a flush mount box while
also having surface mount boxes right there as well. It seemed to me that
you were trying to make too much of the job by trying to get conduit into
the flush mount.




Mike,

Your earlier comments made me think a little more. See if you think the
following idea makes things easier/better:

I could just bend one piece of EMT to run from the switchbox, up the
stud, and finish with a 90 degree bend coalescing with the ceiling,
attaching one those C-type EMT connectors to the end. This eliminates
the "middle" box in my earlier drawing (so no surface-mount boxes).

What do you think; pretty good, no? There's power in numbers (working
together)!

Bill

Bill wrote:

Mike,

Your earlier comments made me think a little more. See if you think
the following idea makes things easier/better:

I could just bend one piece of EMT to run from the switchbox, up the
stud, and finish with a 90 degree bend coalescing with the ceiling,
attaching one those C-type EMT connectors to the end. This eliminates
the "middle" box in my earlier drawing (so no surface-mount boxes).

What do you think; pretty good, no? There's power in numbers
(working together)!


So, am I understanding that you'd remove the current flush mount box and
install a gang box there and run the conduit up the inside of the wall,
along the stud, and then break through at the ceiling? I'm not sure I have
that right because that would pretty much require you cut out sheetrock in
that stud pocket and then refinish it afterwards - not necessarily the worst
solution though. Just don't know that I'm understanding your plan
correctly.

--

-Mike-

In article , Bill wrote:
Scott Lurndal wrote:

--- Begin Quote ---

Section 410-31 of the NEC (1999 Edition) states:

Fixtures shall not be used as a raceway for circuit conductors.

Exception #1: Fixtures listed for use as a raceway
Exception #2: Fixtures designed for end-to-end assembly to
form a continuous raceway or fixtures connected
together by recognized wiring methods shall be permitted
to carry through conductors of a 2-wire or multiwire
branch circuit supplying the fixtures.
Exception #3: One additional 2-wire branch circuit separately supplying
one or more of the connected fixtures described in
exception
#2 shall be permitted to be carried through the fixtures.

Branch-circuit conductors within 3 inches of a ballast within the ballast
compartment shall have an insulation temperature rating not lower than
90 degrees C such as Types RHH, THW, THHN, THHW, FEP, FEPB, SA and XHHW.

--- End Quote ---

Most consumer grade flourescents aren't listed as raceways. That pretty
much leaves exception #2 as the guidance for this application. It also
limits
you to 2 two-wire or 1 three-wire and 1 two-wire branch circuits for the
string of fixtures.


Scott.

There is only 1 15A branch circuit. However, I had planned for it to
"split" through 3 switches in the switchbox and pass the resultant 5
wires--3 hot, 1 neutral, 1 ground, through the fixtures as necessary to
power them. If I understand correctly, this would qualify as a single
2-wire branch circuit, wouldn't it?

Absolutely. It's still one circuit, and it's still a "two-wire branch circuit"
despite there being four wires (the ground is not counted) because your three
hots are derived from the same point.

In any event, since the exception permits a multi-wire branch circuit, that
particular point is moot anyway. It's clearly a single circuit: there's only
one single-pole breaker.

TYVM!
Bill


Do note the "recognized wiring methods".

Which would include, presumably, being connected by a properly-installed
section of EMT.

Please also be aware that the temperature rating of the conductors being
passed through must be at least 90c (THHN should suffice, but never use NM or
NM-B)

scott

Mike Marlow wrote:
Bill wrote:

Mike,

Your earlier comments made me think a little more. See if you think
the following idea makes things easier/better:

I could just bend one piece of EMT to run from the switchbox, up the
stud, and finish with a 90 degree bend coalescing with the ceiling,
attaching one those C-type EMT connectors to the end. This eliminates
the "middle" box in my earlier drawing (so no surface-mount boxes).

What do you think; pretty good, no? There's power in numbers
(working together)!


So, am I understanding that you'd remove the current flush mount box and
install a gang box there and run the conduit up the inside of the wall,
along the stud, and then break through at the ceiling? I'm not sure I have
that right because that would pretty much require you cut out sheetrock in
that stud pocket and then refinish it afterwards - not necessarily the worst
solution though. Just don't know that I'm understanding your plan
correctly.

Thank you for your interest. Yes, that just what I am prepared to do.
I've still working with drywall compound anyway, and I haven't primed
anything yet, so that part is no big deal. The only thing left about it
that seems unorthodox to me is having the EMT come through the wall (6
inches before the ceiling) without some sort of fixture to guide it.
However, it will be securely clamped to the stud befind the wall and to
the ceiling after it exits. You could think of it as an "all EMT"
solution--except part of the EMT lies behind the wall.

Doug Miller wrote:
In , wrote:
Scott Lurndal wrote:

--- Begin Quote ---

Section 410-31 of the NEC (1999 Edition) states:

Fixtures shall not be used as a raceway for circuit conductors.

Exception #1: Fixtures listed for use as a raceway
Exception #2: Fixtures designed for end-to-end assembly to
form a continuous raceway or fixtures connected
together by recognized wiring methods shall be permitted
to carry through conductors of a 2-wire or multiwire
branch circuit supplying the fixtures.
Exception #3: One additional 2-wire branch circuit separately supplying
one or more of the connected fixtures described in
exception
#2 shall be permitted to be carried through the fixtures.

Branch-circuit conductors within 3 inches of a ballast within the ballast
compartment shall have an insulation temperature rating not lower than
90 degrees C such as Types RHH, THW, THHN, THHW, FEP, FEPB, SA and XHHW.

--- End Quote ---

Most consumer grade flourescents aren't listed as raceways. That pretty
much leaves exception #2 as the guidance for this application. It also
limits
you to 2 two-wire or 1 three-wire and 1 two-wire branch circuits for the
string of fixtures.


Scott.

There is only 1 15A branch circuit. However, I had planned for it to
"split" through 3 switches in the switchbox and pass the resultant 5
wires--3 hot, 1 neutral, 1 ground, through the fixtures as necessary to
power them. If I understand correctly, this would qualify as a single
2-wire branch circuit, wouldn't it?

Absolutely. It's still one circuit, and it's still a "two-wire branch circuit"
despite there being four wires (the ground is not counted) because your three
hots are derived from the same point.

In any event, since the exception permits a multi-wire branch circuit, that
particular point is moot anyway. It's clearly a single circuit: there's only
one single-pole breaker.

TYVM!
Bill

Thank you for your confirmation Doug!




Do note the "recognized wiring methods".

Which would include, presumably, being connected by a properly-installed
section of EMT.

Please also be aware that the temperature rating of the conductors being
passed through must be at least 90c (THHN should suffice, but never use NM or
NM-B)

scott

Bill wrote:


Thank you for your interest. Yes, that just what I am prepared to do.
I've still working with drywall compound anyway, and I haven't primed
anything yet, so that part is no big deal. The only thing left about
it that seems unorthodox to me is having the EMT come through the
wall (6 inches before the ceiling) without some sort of fixture to
guide it. However, it will be securely clamped to the stud befind the
wall and to the ceiling after it exits. You could think of it as an
"all EMT" solution--except part of the EMT lies behind the wall.

That would be a fine solution.

--

-Mike-

Bill writes:
Scott Lurndal wrote:

--- Begin Quote ---

Section 410-31 of the NEC (1999 Edition) states:

Fixtures shall not be used as a raceway for circuit conductors.

Exception #1: Fixtures listed for use as a raceway
Exception #2: Fixtures designed for end-to-end assembly to
form a continuous raceway or fixtures connected
together by recognized wiring methods shall be permitted
to carry through conductors of a 2-wire or multiwire
branch circuit supplying the fixtures.
Exception #3: One additional 2-wire branch circuit separately supplying
one or more of the connected fixtures described in exception
#2 shall be permitted to be carried through the fixtures.

Branch-circuit conductors within 3 inches of a ballast within the ballast
compartment shall have an insulation temperature rating not lower than
90 degrees C such as Types RHH, THW, THHN, THHW, FEP, FEPB, SA and XHHW.

--- End Quote ---

Most consumer grade flourescents aren't listed as raceways. That pretty
much leaves exception #2 as the guidance for this application. It also limits
you to 2 two-wire or 1 three-wire and 1 two-wire branch circuits for the
string of fixtures.


Scott.

There is only 1 15A branch circuit. However, I had planned for it to
"split" through 3 switches in the switchbox and pass the resultant 5
wires--3 hot, 1 neutral, 1 ground, through the fixtures as necessary to
power them. If I understand correctly, this would qualify as a single
2-wire branch circuit, wouldn't it?

Yes. The extra wires in this case do not matter[*], since they'll sum to the
maximum branch circuit current (15a, in this case). This is would not be
considered a multiwire branch circuit, however, per article 100 and 210-4, which
requires a potential difference between the ungrounded conductors.

In other words, you have multiple paths for the same branch circuit.

scott
[*] subject to raceway fill guidlines.

Mike Marlow wrote:
Bill wrote:


Thank you for your interest. Yes, that just what I am prepared to do.
I've still working with drywall compound anyway, and I haven't primed
anything yet, so that part is no big deal. The only thing left about
it that seems unorthodox to me is having the EMT come through the
wall (6 inches before the ceiling) without some sort of fixture to
guide it. However, it will be securely clamped to the stud befind the
wall and to the ceiling after it exits. You could think of it as an
"all EMT" solution--except part of the EMT lies behind the wall.

That would be a fine solution.


TYVM, I con't get too many replies to my posts like that! : )