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C & M
 
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Default Wire type needed for underground

I believe that NM is wore code that you are looking for. If I had it to do
again I would have run mine thru sewer/ drain pipe and gone deeper than the
6" that I did run it. Check local code and I'm sure you'll get better infor
from those in the know right here. Don't change your channel - just your
socks!

wrote in message
...
I have a garage that has pvc underground from the house. The wires
that are in there now are #14 and only one circuit. I want to run 3
#12 wires so I have 2 circuits and 20A instead of 15A. There is
plenty of room in the 3/4" conduit. I dont see a reason to buy UF
cable, since it's in conduit. It only has single wires now. My
question is what type of wire to use. I know all wires have a
specific use and numbers on them to designate use. I dont think water
gets in the conduit, but I know that I need wire that is made for wet
locations.

Randy



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twstanley
 
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Default

NM is non metallic ( coating ) I believe, I think what you want is the
direct burial wire unless you are putting it in conduit. Direct burial
wire coating is made to withstand water/dirt/etc without breaking down
and rotting.

  #3   Report Post  
RBM
 
Posts: n/a
Default

If you are looking for direct burial cable, you want "UF". If you want to
run wires in conduit, you want conductors rated for wet location like THWN
"C & M" wrote in message
...
I believe that NM is wore code that you are looking for. If I had it to do
again I would have run mine thru sewer/ drain pipe and gone deeper than
the
6" that I did run it. Check local code and I'm sure you'll get better
infor
from those in the know right here. Don't change your channel - just your
socks!

wrote in message
...
I have a garage that has pvc underground from the house. The wires
that are in there now are #14 and only one circuit. I want to run 3
#12 wires so I have 2 circuits and 20A instead of 15A. There is
plenty of room in the 3/4" conduit. I dont see a reason to buy UF
cable, since it's in conduit. It only has single wires now. My
question is what type of wire to use. I know all wires have a
specific use and numbers on them to designate use. I dont think water
gets in the conduit, but I know that I need wire that is made for wet
locations.

Randy





  #4   Report Post  
PipeDown
 
Posts: n/a
Default

TFFN wire will do fine inside a conduit. You need three insulated pieces
(two hots and a neutral) and one uninsulated ground. Four #12 wires in a
3/4" conduit is acceptable. Since the conduit is nonmetallic, you do not
have to bond the ground wire to it. Continue to use NM J-boxes (the gray
outdoor type you can cement the conduit to it). Make sure to wire each of
the hots to a different phase of the breaker box so that the current in the
neutral subtracts instead of adding up.

I don't think you can run an electrical branch through a known water drain
but if you did it would definitely be UF cable type.

PS. NM (Non metallic) WRT Romex cables only refers to the outer sheath.
Running bundled cables like Romex NM-B 12-3 cable through the conduit is
certainly possible but the use of bundled cables inside the conduit would
require derating of the ampacity of those wires makeing it as an effective
#14 (or so depending on the distance) because of the reduced ability of that
wire to shed heat. It is therefore more desireable to run individual wires.


"C & M" wrote in message
...
I believe that NM is wore code that you are looking for. If I had it to do
again I would have run mine thru sewer/ drain pipe and gone deeper than
the
6" that I did run it. Check local code and I'm sure you'll get better
infor
from those in the know right here. Don't change your channel - just your
socks!

wrote in message
...
I have a garage that has pvc underground from the house. The wires
that are in there now are #14 and only one circuit. I want to run 3
#12 wires so I have 2 circuits and 20A instead of 15A. There is
plenty of room in the 3/4" conduit. I dont see a reason to buy UF
cable, since it's in conduit. It only has single wires now. My
question is what type of wire to use. I know all wires have a
specific use and numbers on them to designate use. I dont think water
gets in the conduit, but I know that I need wire that is made for wet
locations.

Randy





  #5   Report Post  
PipeDown
 
Posts: n/a
Default

THWN would be more appropriate than TFFN but these wire types and conduit
fill tables can be looked up in just about any wiring book based on just
about any code version. CodeCheck Electrical is a very conscise reference
with the most important stuff for DIYers nad does contain the complete
answer to this question. There are many other code referecnes too. What I
don't recommend is the NEC book all by itself since stuff is pretty hard to
find if you don't already know where to look (almost no pictures or
diagrams).



"PipeDown" wrote in message
nk.net...
TFFN wire will do fine inside a conduit. You need three insulated pieces
(two hots and a neutral) and one uninsulated ground. Four #12 wires in a
3/4" conduit is acceptable. Since the conduit is nonmetallic, you do not
have to bond the ground wire to it. Continue to use NM J-boxes (the gray
outdoor type you can cement the conduit to it). Make sure to wire each of
the hots to a different phase of the breaker box so that the current in
the neutral subtracts instead of adding up.

I don't think you can run an electrical branch through a known water drain
but if you did it would definitely be UF cable type.

PS. NM (Non metallic) WRT Romex cables only refers to the outer sheath.
Running bundled cables like Romex NM-B 12-3 cable through the conduit is
certainly possible but the use of bundled cables inside the conduit would
require derating of the ampacity of those wires makeing it as an effective
#14 (or so depending on the distance) because of the reduced ability of
that wire to shed heat. It is therefore more desireable to run individual
wires.


"C & M" wrote in message
...
I believe that NM is wore code that you are looking for. If I had it to
do
again I would have run mine thru sewer/ drain pipe and gone deeper than
the
6" that I did run it. Check local code and I'm sure you'll get better
infor
from those in the know right here. Don't change your channel - just your
socks!

wrote in message
...
I have a garage that has pvc underground from the house. The wires
that are in there now are #14 and only one circuit. I want to run 3
#12 wires so I have 2 circuits and 20A instead of 15A. There is
plenty of room in the 3/4" conduit. I dont see a reason to buy UF
cable, since it's in conduit. It only has single wires now. My
question is what type of wire to use. I know all wires have a
specific use and numbers on them to designate use. I dont think water
gets in the conduit, but I know that I need wire that is made for wet
locations.

Randy









  #6   Report Post  
Bud
 
Posts: n/a
Default

PipeDown wrote:



"PipeDown" wrote in message
nk.net...

TFFN wire will do fine inside a conduit. You need three insulated pieces
(two hots and a neutral) and one uninsulated ground. Four #12 wires in a
3/4" conduit is acceptable. Since the conduit is nonmetallic, you do not
have to bond the ground wire to it. Continue to use NM J-boxes (the gray
outdoor type you can cement the conduit to it). Make sure to wire each of
the hots to a different phase of the breaker box so that the current in
the neutral subtracts instead of adding up.

THWN would be more appropriate than TFFN but these wire types and

conduit
fill tables can be looked up in just about any wiring book based on just
about any code version. CodeCheck Electrical is a very conscise

reference
with the most important stuff for DIYers nad does contain the complete
answer to this question. There are many other code referecnes too.

What I
don't recommend is the NEC book all by itself since stuff is pretty

hard to
find if you don't already know where to look (almost no pictures or
diagrams).


TFFN is fixture wire and is not OK. THWN is often rated THWN and THHN.

Bud--
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