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Re: Short Plenum Run Question
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That's the same solution that came to mind as I studied your diagram. =
Just put a piece of metal over the wires to isolate them from the air =
circulation area. You might it easiest to do using a couple of 14.5" =
lengths of light gauge metal stud material. You should just be able to =
drop them in with the legs pointing down between the drywall. (Upside =
down U).
| __ |
||X || =20
The outer lines are the wall or grates. X is the wire. The lines on both =
sides and above the X is the piece of metal stud. The underline is the =
baseplate.
From:Theron
scary_penguin@xxxxxxxxxxx
> Frank Olson wrote:
>> Theron wrote:
>>> L. M. Rappaport wrote:
>>>=20
>>>> On 29 Nov 2005 01:06:59 -0800, robertlbass@xxxxxxxxxxx wrote (with
>>>> possible editing):
>>>>=20
>>>>=20
>>>>>> In addition to Robert's coments, building codes may allow you to
>>>>>> run=20
>>>>>=20
>>>>> standard FT-4 as well (for communications and network)...
>>>>>=20
>>>>> NOT in a duct. This is a duct -- not a plenum -- and US code
>>>>> does not permit any cables within it except those necessary to
>>>>> operate the duct.=20
>>>>>=20
>>>>>=20
>>>>>> In Vancouver (for instance) you don't need to run plenum
>>>>>> rated wire in a plenum if the total length of the wire run
>>>>>> (from panel to device) doesn't exceed 9 meters...
>>>>>=20
>>>>> Same here although the distance isn't the same, but that rule
>>>>> does not apply to ducts.
>>>>>=20
>>>>> Regards,
>>>>> Robert L Bass
>>>>> www.BassBurglarAlarms.com
>>>>=20
>>>> While you're right about those cables not being allowed in a duct,
>>>> I am still not so sure it's a duct and not a plenum. I've read and
>>>> re-read his post and it still isn't clear to me. It doesn't sound
>>>> like everything is enclosed in tin and the wires may be below the
>>>> tin part. That sounds like a plenum, not a duct.
>>>>=20
>>>> Theron - do the wires go through a channel enclosed on all sides by
>>>> sheet metal or is the only sheet metal on the top?
>>>>=20
>>>> No flame, just trying to visualize what he has.
>>>=20
>>>=20
>>> Sorry - this is much more complicated than I imagined, but I
>>> appreciate the help.
>>>=20
>>> Here's what I have - I have an interior wall in my basement, running
>>> North-South and framed by 2x4 lumber separated 16" on center. Two
>>> adjacent gaps in the framed wall serve as a cold air return for the
>>> furnace, as follows.
>>>=20
>>> On the West side of the wall is a living area, and the furnace is on
>>> the East side of the wall. On the relevant area, the west side of
>>> the wall is tin, the east side is drywall.
>>>=20
>>> On the east side, I have a 30" wide grate about 6" off the ground to
>>> allow air into the wall. On the west side, I have two 8" ducts that
>>> run from the wall to the furnace's main cold air return to allow the
>>> furnace to draw air from the basement, through the wall. Those
>>> ducts are about 3-4' from the ground.
>>>=20
>>> At about 3" off the baseplate, I have a set of holes drilled through
>>> the 2x4s on center running four cat 5e cables (3 phone, 1 ethernet).
>>> Therefore, the cables run for about 30" across the bottom of the
>>> gap in the wall I am using to feed cold air into the furnace.
>>>=20
>>> Here's an ascii, which should come out right with a non-proportional
>>> font:
>>>=20
>>> Top View Side View
>>>=20
>>> D x D F F F
>>> D x D F 8 F 8 F
>>> G x T888 F F F
>>> G x T F F F
>>> G x T888 F F F
>>> D x D GGGGGGGGGGGGG
>>> D x D GGGGGGGGGGGGG
>>> FxxxxxFxxxxxF
>>> FFFFFFFFFFFFF
>>>=20
>>> D =3D Drywall x =3D cat 5e cable, non-plenum rated
>>> T =3D Tin 8 =3D 8 inch duct to main cold air return
>>> G =3D grate F =3D Framing lumber
>>>=20
>>=20
>>=20
>> Looks to me like you've got a plenum and not a "duct". Now if you
>> were to ask your local AHJ, he would tell you what you've done is a
>> very big "no-no". In fact, in most instances (and jurisidictions),
>> he may even make you remove it. I don't believe you're allowed to
>> run *any* wire, combustible piping, etc. inside a cold air return
>> although I have seen a couple of instances where vacuum piping was
>> passed (go figure). If you absolutely *have* to have it there, see
>> if you can enclose it in metal conduit or a short run of BX (yes, it
>> may mean you're going to have at least one splice). The better way
>> would be to find another route for your wire but that may not always
>> be possible at this late stage.=20
>=20
> My current plan is just to install a firestop between the cables and
> the plenum or duct or whatever it is. Since the cables are actually
> below the grate, I can toenail some 14 1/2" blocks across the gaps and
> block the area with the cables from the area where I want cold air to
> circulate. (That's what I would have done if I had realized what I
> was doing at the time).
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<DIV><SPAN class=3Dq0>That's the same solution that came to mind as I =
studied your=20
diagram. Just put a piece of metal over the wires to isolate them from =
the air=20
circulation area. You might it easiest to do using a couple of 14.5" =
lengths of=20
light gauge metal stud material. You should just be able to drop them in =
with=20
the legs pointing down between the drywall. (Upside down =
U).</SPAN></DIV>
<DIV><SPAN class=3Dq0><FONT size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3Dq0><FONT size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3Dq0><FONT size=3D2> </FONT><FONT size=3D3> | =
__=20
|</FONT></SPAN></DIV>
<DIV><SPAN class=3Dq0><FONT size=3D2> </FONT><FONT size=3D3><U>||X =
||</U> </FONT></SPAN></DIV>
<DIV><SPAN class=3Dq0><FONT size=3D3></FONT></SPAN> </DIV>
<DIV><SPAN class=3Dq0><FONT size=3D3>The outer lines are the wall =
or grates. X=20
is the wire. The lines on both sides and above the X is the piece of =
metal stud.=20
The underline is the baseplate.</FONT></DIV>
<DIV><BR><BR><FONT=20
size=3D2>From:Theron<BR>scary_penguin@xxxxxxxxxxx<BR><BR></FONT></SPAN><S=
PAN=20
class=3Dq1><FONT size=3D2>> Frank Olson wrote:<BR></FONT></SPAN><SPAN =
class=3Dq2><FONT size=3D2>>> Theron wrote:<BR></FONT></SPAN><SPAN=20
class=3Dq3><FONT size=3D2>>>> L. M. Rappaport =
wrote:<BR>>>>=20
<BR></FONT></SPAN><SPAN class=3Dq4><FONT size=3D2>>>>> On 29 =
Nov 2005=20
01:06:59 -0800, robertlbass@xxxxxxxxxxx wrote (with<BR>>>>> =
possible=20
editing):<BR>>>>> <BR>>>>> =
<BR></FONT></SPAN><SPAN=20
class=3Dq6><FONT size=3D2>>>>>>> In addition to =
Robert's coments,=20
building codes may allow you to<BR>>>>>>> run=20
<BR></FONT></SPAN><SPAN class=3Dq5><FONT size=3D2>>>>>>=20
<BR>>>>>> standard FT-4 as well (for communications and=20
network)...<BR>>>>>> <BR>>>>>> NOT in a=20
duct. This is a duct -- not a plenum -- and US=20
code<BR>>>>>> does not permit any cables within it except =
those=20
necessary to<BR>>>>>> operate the duct. =
<BR>>>>>>=20
<BR>>>>>> <BR></FONT></SPAN><SPAN class=3Dq6><FONT=20
size=3D2>>>>>>> In Vancouver (for instance) you don't =
need to=20
run plenum<BR>>>>>>> rated wire in a plenum if the =
total=20
length of the wire run<BR>>>>>>> (from panel to =
device)=20
doesn't exceed 9 meters...<BR></FONT></SPAN><SPAN class=3Dq5><FONT=20
size=3D2>>>>>> <BR>>>>>> Same here =
although the=20
distance isn't the same, but that rule<BR>>>>>> does not =
apply to=20
ducts.<BR>>>>>> <BR>>>>>>=20
Regards,<BR>>>>>> Robert L Bass<BR>>>>>>=20
www.BassBurglarAlarms.com<BR></FONT></SPAN><SPAN class=3Dq4><FONT=20
size=3D2>>>>> <BR>>>>> While you're right about =
those=20
cables not being allowed in a duct,<BR>>>>> I am still not =
so sure=20
it's a duct and not a plenum. I've read and<BR>>>>> =
re-read=20
his post and it still isn't clear to me. It doesn't=20
sound<BR>>>>> like everything is enclosed in tin and the =
wires may=20
be below the<BR>>>>> tin part. That sounds like a =
plenum, not=20
a duct.<BR>>>>> <BR>>>>> Theron - do the wires =
go=20
through a channel enclosed on all sides by<BR>>>>> sheet =
metal or is=20
the only sheet metal on the top?<BR>>>>> =
<BR>>>>> No=20
flame, just trying to visualize what he has.<BR></FONT></SPAN><SPAN=20
class=3Dq3><FONT size=3D2>>>> <BR>>>> <BR>>>> =
Sorry -=20
this is much more complicated than I imagined, but I<BR>>>> =
appreciate=20
the help.<BR>>>> <BR>>>> Here's what I have - I have =
an=20
interior wall in my basement, running<BR>>>> North-South and =
framed by=20
2x4 lumber separated 16" on center. Two<BR>>>> adjacent =
gaps in=20
the framed wall serve as a cold air return for the<BR>>>> =
furnace, as=20
follows.<BR>>>> <BR>>>> On the West side of the wall =
is a=20
living area, and the furnace is on<BR>>>> the East side of the=20
wall. On the relevant area, the west side of<BR>>>> the =
wall is=20
tin, the east side is drywall.<BR>>>> <BR>>>> On the =
east=20
side, I have a 30" wide grate about 6" off the ground to<BR>>>> =
allow=20
air into the wall. On the west side, I have two 8" ducts=20
that<BR>>>> run from the wall to the furnace's main cold air =
return to=20
allow the<BR>>>> furnace to draw air from the basement, through =
the=20
wall. Those<BR>>>> ducts are about 3-4' from the=20
ground.<BR>>>> <BR>>>> At about 3" off the baseplate, =
I have a=20
set of holes drilled through<BR>>>> the 2x4s on center running =
four cat=20
5e cables (3 phone, 1 ethernet).<BR>>>> Therefore, the cables =
run for=20
about 30" across the bottom of the<BR>>>> gap in the wall I am =
using to=20
feed cold air into the furnace.<BR>>>> <BR>>>> Here's =
an=20
ascii, which should come out right with a =
non-proportional<BR>>>>=20
font:<BR>>>> <BR>>>> Top=20
View =
Side=20
View<BR>>>> <BR>>>> D x=20
D =20
F F =20
F<BR>>>> D x=20
D =
F =20
8 F 8 F<BR>>>> G x=20
T888 =
F =20
F F<BR>>>> G x=20
T =20
F F =20
F<BR>>>> G x=20
T888 =
F =20
F F<BR>>>> D x=20
D =20
GGGGGGGGGGGGG<BR>>>> D x=20
D =20
GGGGGGGGGGGGG<BR>>>> &n=
bsp; =20
FxxxxxFxxxxxF<BR>>>> &n=
bsp; =20
FFFFFFFFFFFFF<BR>>>> <BR>>>> D =3D=20
Drywall x =3D cat 5e cable, non-plenum=20
rated<BR>>>> T =3D=20
Tin &nbs=
p; 8 =3D=20
8 inch duct to main cold air return<BR>>>> G =3D=20
grate F =3D Framing=20
lumber<BR>>>> <BR></FONT></SPAN><SPAN class=3Dq2><FONT =
size=3D2>>>=20
<BR>>> <BR>>> Looks to me like you've got a plenum and not a =
"duct". Now if you<BR>>> were to ask your local AHJ, he =
would tell=20
you what you've done is a<BR>>> very big "no-no". In fact, =
in most=20
instances (and jurisidictions),<BR>>> he may even make you remove=20
it. I don't believe you're allowed to<BR>>> run *any* wire,=20
combustible piping, etc. inside a cold air return<BR>>> although I =
have=20
seen a couple of instances where vacuum piping was<BR>>> passed =
(go=20
figure). If you absolutely *have* to have it there, =
see<BR>>> if you=20
can enclose it in metal conduit or a short run of BX (yes, =
it<BR>>> may=20
mean you're going to have at least one splice). The better =
way<BR>>>=20
would be to find another route for your wire but that may not =
always<BR>>>=20
be possible at this late stage. <BR></FONT></SPAN><SPAN class=3Dq1><FONT =
size=3D2>> <BR>> My current plan is just to install a firestop =
between the=20
cables and<BR>> the plenum or duct or whatever it is. Since the =
cables=20
are actually<BR>> below the grate, I can toenail some 14 1/2" blocks =
across=20
the gaps and<BR>> block the area with the cables from the area where =
I want=20
cold air to<BR>> circulate. (That's what I would have done if I =
had=20
realized what I<BR>> was doing at the=20
time).</FONT></SPAN></DIV></BODY></HTML>
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