Replies

1. 
   pm22 | May 22, 2006 04:30am | #1

   PVC doesn't rust but it might sag a bit more. So use a couple more straps. The wires inside are made of copper so they should be fine. You can pull NMB [Romex] through conduit for protection. With a conduit system, you must protect the wires all the way to the box.

   ~Peter

   Time is running out for Seattle and poor little Tacoma. Even Pat Robertson agrees.

1. 
   stantheman987 | May 22, 2006 08:40pm | #4

   Thanks. I was under the (mis)impression that code required pulling individual wires thru conduit instead of Romex. Do you think there's an issue with PVC degrading in the sun?

1. 
   BillHartmann | May 22, 2006 10:05pm | #11

   "Thanks. I was under the (mis)impression that code required pulling individual wires thru conduit instead of Romex."You can pull cable through conduit. However, you need to size the conduit as though you had a wire the same diameter as the widest part of the cable.So you need fairly large conduit and it is not each to pull.However, there is an exception if the conduit is only used to sleave the cable such as a run from the joist down a basement wall. Or UF where it surfaces before it enters the wall.

2. 
   maddog3 | May 22, 2006 05:07am | #2

   there is PVC, which must be protected from physical damage....like weedwhackers,lawn mowers,and thoughtless people...

   there is also Aluminum ridgid, which is easy to cut and thread, it is also easy bend...sometimes in the wrong spot. and if you leave some cutting oil on the pipe it also turns your skin and clothing black at no extra charge..

   ...I use mineral spirits for threading....sshhh

   and of course good 'ol GRC, which would most likely be a big PITA

   _______________________
   edit:

   you might consider using THHN instead of NM due to the huge price increases in both wire and Romex...unless you have the stuff laying around
   .
   .

   'Wer ist jetzt der Idiot?'

   
   

   ---

   Edited 5/21/2006 10:20 pm by maddog3

1. 
   stantheman987 | May 22, 2006 08:48pm | #5

   This run would be running vertically up the side of the house, so it's relatively safe from abuse. I was hoping to avoid threading altogether by using fittings that have set screws to hold the conduit. I'll probably only need 2 LB's for getting through the siding, in and out, and one 90 degree bend.Is the THNN available as individual wires only?Thanks.

1. 
   maddog3 | May 23, 2006 12:54am | #13

   ...."Is the THNN available as individual wires only? " for what you are doing....yes, but I thought the wires in Romex were THHN.!!!..also, if you are going to use PVC, be sure the coupling bells point DOWN as they are not watertight.

   .

   .

   'Wer ist jetzt der Idiot?'

1. 
   JohnSprung | May 24, 2006 12:41am | #23

   Putting the PVC bells facing down may be a good belt-and-suspenders idea, but I'd think that with the plastic cement they'd be about as good as PVC water pipe, no?  

    

   -- J.S.

    

1. 
   maddog3 | May 24, 2006 02:21am | #26

   ..no not really... ALL pipes in duct banks can fill with water overnight.

   .

   .

   'Wer ist jetzt der Idiot?'

2. 
   sparkytim | May 23, 2006 09:29am | #19

   It sound like you are going to be using PVC, but in case you do decide to go with EMT, don't use the set screw type connectors,  they are not water tight and not rated for out door use.  1/2 and 3/4 in pvc needs to be supported every 3 feet to meet code, but even then it may still not stay straight.

1. 
   stantheman987 | May 23, 2006 03:50pm | #20

   Thanks - yet another reason to use PVC: I don't have the equipment to thread EMT and this job is too small to make renting worth it...

1. 
   sparkytim | May 24, 2006 12:26am | #22

   Your'e scaring me.  You don't thread EMT.  To make it water tight you use compression fittings.

2. 
   stantheman987 | May 24, 2006 12:54am | #25

   Sorry for the ignorance (and scare). My bad, I was confusing it with IMT. I'm a newbie with the jargon...

2. 
   timothale | May 23, 2006 07:34pm | #21

   I don't have my 2006 nec elect code book with me but i think if you run more than 2 feet of romex thru a conduit it will not disapate heat and you are suppose to derate the circuiot,  larger conduit and larger wires usually  will recalc for the load

1. 
   sparkytim | May 24, 2006 12:49am | #24

   I Haven't bought the 2005 NEC yet, but the 2002 NEC sec334.15(B) states:

   (B) Protection from Physical Damage.  The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means. ...

   Isn't sch 40 PVC a listed surface nonmetallic raceway?  Interesting.

    

   Tim

2. 
   toolbear | May 24, 2006 04:07am | #28

   B) Protection from Physical Damage.  The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means. ...

   Got a point.  As I recall, when we daylight the stuff, we run in P 80.  Under roadways I have run triplex DB feeders in P 80.  Up the utility pole it's P80.

   Best he run P 80 up the wall.  Besides, less flex.  Might not look like a snake come summer. 

   But why do we worry?  Visting NY state, I saw all sorts of homes with festoons of service entrance cable run up the sides.  Serious eyesores.  The ToolBear

   "Never met a man who couldn't teach me something." Anon.

3. 
   stantheman987 | May 26, 2006 05:11pm | #30

   So running individual wires (not NM cable)is preferred?

4. 
   DanH | May 26, 2006 06:59pm | #31

   Preferred by the guy pulling the wire through the conduit.
   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

5. 
   stantheman987 | May 26, 2006 08:28pm | #32

   Granted, an easier pull. But Timothale implies it also effects cable and conduit derating because of heat dissipation.

6. 
   DanH | May 26, 2006 08:36pm | #33

   Yeah, at least in theory. The spec is a little fuzzy in this area, given the fairly large number of special qualifications and exemptions.
   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

7. 
   BillHartmann | May 26, 2006 09:07pm | #34

   "But Timothale implies it also effects cable and conduit derating because of heat dissipation."That is urban legend. There is on other derating of cable just because it is in a conduit.Now there are derating for high anbinet tempatures and for a number of bundled conductors (and conduit is one form of bundeling). But that is the same regardless if it is individual wires or cable(s).The sizing of the conduit and pull of the cable are the main isues.

8. 
   stantheman987 | May 26, 2006 09:21pm | #35

   Thanks for the clarification. Your posts are much appreciated.

3. 
   toolbear | May 22, 2006 05:46am | #3

   @@@ Looking rotten...

   You might check the wires.  I am doing another area wiring job tomorrow.  Been finding serious galvanic corrosion where the wires exit into the Alum. boxes.  Wires broken.  Wires with missing insulation.  Wires down to pen points.  Box fires.  Your boxes steel or what?

   The original wiring I deal with was run in 1/2 steel rigid, which tends to rot out, but I find the wires down in the conduit are looking good.  It's where they enter the box that it gets fun. 

   I am using wire harness loom as insulation for the wires where they enter my boxes.

   All threads are doped with Never Seize and the wire nuts doped with NoOx.

   The ToolBear

   "Never met a man who couldn't teach me something." Anon.

1. 
   stantheman987 | May 22, 2006 08:54pm | #6

   I haven't looked closely at the boxes, just saw the condition of the external conduit yesterday, so I'm not sure if they're steel or not. From what you've said, I should match the conduit to the box material to prevent the galvanic action. Thanks, I didn't think of that.

1. 
   BryanSayer | May 22, 2006 09:32pm | #8

   Similar METAL materials. PVC can be fastned to metal boxes with the correct connectors.I've got a similar problem with an AC shutoff on the roof. The connector from the AC whip into the metal box has completly rusted.

1. 
   DanH | May 22, 2006 09:43pm | #9

   I might mention that another option is weathertight flex. PVC is better if it's just a straight shot, but if there need to be any twists and turns the flex is the way to go.
   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

1. 
   BillHartmann | May 22, 2006 10:01pm | #10

   "I might mention that another option is weathertight flex. PVC is better if it's just a straight shot, but if there need to be any twists and turns the flex is the way to go."Or a combination.I have run underground conduit a couple of places where I can get near the wall or post because of concrete footers.So I run the PVC in the trench and then the 90 up to the surface. Then a wipe of flex to bring it to the box.

2. 
   BryanSayer | May 22, 2006 10:20pm | #12

   And the connection from the shut-off to the AC compressor has to be flex. I guess when mine was done originally, they had metal connectors. I suspect I will have to replace the entire whip.

2. 
   toolbear | May 23, 2006 05:26am | #15

   I am putting my work together with Never Seize on all the threads so the next poor bastard can get it apart.  Got the nuts off the rigid on my project today - adjustable wrench plus pipe wrench.  Usually don't need two wrenches.

   Left the wires in the broken rigid potted up in caulk to keep them in the middle of the pipe and away from the edges. 

   Anyone have a sure fire way to cut the pipe and not the wires, do tell.  That lead runs to the gate, about 250'.  We already replaced another leg of it.

   The center run on the box appears to be done in a 3/8" garden hose wrapped in black tape.  Like to know what tape they used.  It's in excellent shape.   Boss won't let me connect this one back up.  Liability.  Darn.  Could sleeve it neatly in P40.

   I looked in the catalog for a PVC-steel transition.  Sure they make one, but not found. My solution is an irrigation compression sleeve in 0.5".  One end compresses around the rigid and I insert the PVC in the other end.  Wrong color, but it works.The ToolBear

   "Never met a man who couldn't teach me something." Anon.

1. 
   jazzdogg | May 23, 2006 05:43am | #17

   "Anyone have a sure fire way to cut the pipe and not the wires, do tell."

   TB,

   What about the kind of tubing cutter that you use by turning it 'round and 'round copper plumbing pipe, tightening it a smidge with each rotation? The small, though sharp, cutting wheel seems unlikely to do much damage to THHN unless operated by a ham-fisted dolt - though it would likely take longer than a hacksaw or sawzall.

    -Jazzdogg-

   "Don't ask yourself what the world needs. Ask yourself what makes you come alive, and go do that, because what the world needs is people who have come alive." Gil Bailie

1. 
   toolbear | May 24, 2006 03:53am | #27

   @@@ Tubing cutter -

   Yes, boss has one.  Sez it will cut pipe.  Problem with old steel conduit when buried - rustacles.

   The stuff may have been 1/2 new, but now it's 3/4 to 1 with rust blisters. 

   Suppose one could knock the stuff off and grind it smooth.  Our approach has been:

        "Dude, you're getting a new circuit leg."

   Actually, two.  The HOA decided that circuits run in 3/8 garden hose was over the top and had to go.  So we extended the trench to the next light and I ran fresh wire over there. 

   Gotta wonder.  The car ports are fed with a nice 50A circuit.  The irrigation panel next to the carports was fed from the same loadcenter on about 400' of 14 AWG.  Duh!  Why not just connect to the CP feeder?The ToolBear

   "Never met a man who couldn't teach me something." Anon.

2. 
   BruceT999 | May 23, 2006 06:41am | #18

   Hey TB,Can you get a pipe cutter on that rigid? Clean cut and easy to control.BruceT

1. 
   toolbear | May 25, 2006 04:48am | #29

   Pipe cutter -

   I might find a nice spot betweet rustacles and grind it smooth.   Will have to dig out around it 360 to rotate cutter, so the little one is of interest. 

    

    The ToolBear

   "Never met a man who couldn't teach me something." Anon.

4. 
   DanH | May 22, 2006 09:28pm | #7

   Unless there's a danger of physical damage, use PVC -- no future problems with corrosion. Make sure the stuff you buy is labeled "UV resistant" or "Sunlight resistant" or whatever. You should be able to buy transition fittings between the plastic and any inside steel conduit you'll want to leave in place.

   The wire inside the conduit is probably OK, but you'll need to pull it out in order to replace the conduit, so you may want to replace it on general priniciple.

   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
1. 
   stantheman987 | May 23, 2006 02:52am | #14

   Thanks, everybody. That's what I love about this forum: good, practical advice! I'll go with the UV resistant PVC and run new wires.

2. 
   toolbear | May 23, 2006 05:29am | #16

   @@@ UV RESIST...

   Paint over the run once it's installed.  That should give a bit more protection from sunlight.

    The ToolBear

   "Never met a man who couldn't teach me something." Anon.