Outside conduit wiring

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  #1  
Old 06-26-06, 11:37 AM
jwr
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Outside conduit wiring

Plan to do an outside wiring project-GFI receptacle and a floodlight. I am using PVC conduit. I was planning on using regular romex type wiring. A buddy of mine said that I should use THHN wires-he said that is code here in NY when not running underground. He stated something about regular romex when in conduit will overheat or something. If i do go with the THHN wiring can I run an unshielded ground or does that have to be shielded. Please enlighten me. Thanks.
 
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  #2  
Old 06-26-06, 12:06 PM
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If your conduit is outside then you cannot use NM cable ("Romex" is a name brand) and you cannot use THHN. Neither of those is waterproof.

Outside wiring requires either UF cable, THWN wire in conduit, or some other waterproof wiring method. Usually you will find dual rated THHN/THWN, which is okay for outdoor use in conduit.

Why donít you describe the entire project and we can go from there.
 
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Old 06-26-06, 12:26 PM
jwr
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Thanks for the reply. Project is a new 20amp service to an outside GFCI then onto a security/floodlight. Main panel is on the wall opposite where I want to mount the GFCI. I was going use the pvc conduit because of ease and I am famaliar with pvc. When did this THWN/THHN become code? Reasons? I would rather be code compliant. Can I run a bare ground or does it have to be coated? Where the THWN/THHN wiring goes from the outside wall/receptacle to the main panel does it need to be in conduit as well? This THWN/THHN wire is it solid or stranded? Any other special considerations? Connectors? Thanks again.
 
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Old 06-26-06, 01:06 PM
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You still have not completely described the circuit. Where do the wires run? Do they run outside or do they remain in they walls?

Individual conductors must always be in conduit or in a junction box. They can never be run loose.

For your setup a bare ground is okay, but it is usually better to run an insulated ground wire.

PVC conduit is not allowed indoors.

I think you need to do quite a bit of reading before you do this project.
 
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Old 06-26-06, 01:28 PM
jwr
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Sorry for the incomplete information. Let me start from the beginning;Service panel is inside my garage,the new circuit would leave the bottom of the service panel and go through outside sheathing on the same wall to an outside mounted receptacle with a GFCI outlet. From there it would leave in pvc conduit vertically approx 10ft to my eave where it would connect to a floodlight that would be mounted to a box. No wires would be exposed outside.
Now that I know that I can run a bare or insulated ground wire. My only question is the short piece of wiring from the bottom of the service panel to the outside box. Can I run NM cable from the box to the outside box and tie into the THWN wiring at the outside box? Remember that small portion would be inside the house. Or does it have to be THWN wiring throughout? In that case since pvc conduit is not allowed indoors I would have to run rigid conduit since these are individual conductors. Correct?
I have done my fair share of inside wiring throughout my house working with NM. This is my first venture on the outside. Thanks again.
 
  #6  
Old 06-26-06, 02:13 PM
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As long as NM is allowed where you live, you can use NM. However, since the cable would be exposed in your garage, use small pieces of conduit in yoiur garage to protect the cable.

Outside the house in conduit (schedule 80 ) use THWN.
 
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Old 06-26-06, 02:20 PM
jwr
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Thanks again.
Why did they change code on this? I look at other earlier (10yr.plus) outside wiring around my house and I see NM in rigid conduit. Just curious.
 
  #8  
Old 06-26-06, 03:02 PM
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They did not change the code. NM has never been allowed outside. Perhaps you see UF in conduit.
 
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Old 07-28-06, 11:15 AM
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I did a search and see this question comming up many times. What I don't completely understand is this 'heating' issue.

Example: 12 guage for a 20 amp circuit using a single 12/2 "Romex" cable vs three separate 12 guage conductors in the same conduit; it's the same wire guage and (assuming) the same current draw. Both sets of conductors will get just as warm (same guage). Just because there is double insulation on the 'bundled' cable, really, just how much difference is there going to be??

I understand running two cables in a small diameter conduit (say 1") might be a issue, but running a single (say, 10 guage for voltage drop) in a 1 1/2" conduit, how can that be a issue??
 
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Old 07-29-06, 01:17 AM
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Originally Posted by videobruce
I did a search and see this question comming up many times. What I don't completely understand is this 'heating' issue.
NM inside a conduit is not a heating issue. It is allowed. NM is not rated for damp or wet locations. The OP said that this would be outside. Since it is above ground level I would call it a damp location. Individual strands of THWN in conduit or Type UF cable are allowed.

Since it is exposed on a wall The best suggestion is to use the individual strands in conduit.
 
  #11  
Old 07-29-06, 05:06 AM
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Then Romex IS allowed IN conduit ABOVE ground??

(note the caps)
 
  #12  
Old 07-29-06, 07:14 AM
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Originally Posted by videobruce
Then Romex IS allowed IN conduit ABOVE ground??

(note the caps)
I would word it like this: Then Romex IS allowed IN conduit In DRY Locations??
Many damp or wet locations are above ground level.
 
  #13  
Old 07-29-06, 07:15 AM
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Cable

What's NM and UF accronyms stand for? I heard of ROMEX for indoor use or outside in conduit, but not these?
 
  #14  
Old 07-29-06, 07:36 AM
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Ok on the "dry" locations

Non-metalic
Underground-feeder
 
  #15  
Old 07-29-06, 09:14 AM
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Originally Posted by eeee
What's NM and UF accronyms stand for? I heard of ROMEX for indoor use or outside in conduit, but not these?
NM is non metalic sheethed cable. Romex is one brand name.
UF is undergound feeder cable.

NM is not approved for damp or wet locations.
 
  #16  
Old 07-29-06, 09:59 AM
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I think I just said that.
 
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