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#1
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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 |
#2
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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
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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
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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
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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
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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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