The Jalopy Journal

lenanci · 03-05-2009, 05:01 PM

I'm running 3#4 wires and #10 ground through the attic (70') to a sub panel for my detached garage. I'm getting conflicting information about what kind of conduit to use, PVC or EMT. Obviously PVC would be cheaper but I want it to be safe. The detached garage is permitted in Phoenix, AZ and there will be no inspection in the attic. Code, 2005 NEC.

mrb · 03-05-2009, 05:30 PM

whether or not there will be inspection is irrelevant, do it right regardless.

what code are you under? You probably need a ground too, not just 3 wires.

nadogail · 03-05-2009, 06:10 PM

Four Wires Shipmate, TWO HOTS, A NEUTRAL and a GROUND.

I too vote for PVC in your attic.

walrus · 03-05-2009, 06:45 PM

Does Phoenix derate for the extreme heat found in an attic out there? PVC would do the sag thing in that heat??

sberry · 03-09-2009, 09:27 AM

Agreed, this needs an 8 ground wire.

gdf_77 · 03-11-2009, 10:52 AM

the nec gives a min amount of support for conduit, so in an area where you may be worried about the conduit sagging you can always go above and beyond the minimum. since more than likely your attic won't get near 200 degrees F (90 deg C) derating probably won't be an issue. to be safe you could go to the next size conduit.

gdf_77 · 03-11-2009, 10:53 AM

i too would run pvc.

pipehack · 03-11-2009, 11:07 AM

E.M.T. !!!!!!!! I am very anti P.V.C. strictly because I'm in the trades. If the guy at home depot is so smart then why does he work at home depot.?? Don't take any of their advice seriously.. How much are you really going to save by using P.V.C. ??

Aceman · 03-11-2009, 06:01 PM

Quote:

Originally Posted by gdf_77

since more than likely your attic won't get near 200 degrees F (90 deg C) derating probably won't be an issue. to be safe you could go to the next size conduit.

Derating starts at 87 degrees, not 200. What does conduit size have to do with derating?

Quote:

Originally Posted by pipehack

If the guy at home depot is so smart then why does he work at home depot.

Who said anything about a guy at Home Depot?

lenanci · 03-11-2009, 11:19 PM

I plan on installing 1 1/4" PVC in the attic on top of the roof joists that are 2' OC. 1 1/4" is $3.48 for 10'. EMT is $9.89 for a $10 piece. I need 60'. Big cost difference. Also it would be a major pain to get EMT up there with bends.

03-05-2009, 05:30 PM	#2
mrb Senior Member Join Date: Dec 2008 Posts: 3,742	Re: Conduit In Attic whether or not there will be inspection is irrelevant, do it right regardless. what code are you under? You probably need a ground too, not just 3 wires.

03-05-2009, 06:10 PM	#3
nadogail Senior Member Join Date: Jan 2009 Location: Coronado, CA Posts: 298	Re: Conduit In Attic Four Wires Shipmate, TWO HOTS, A NEUTRAL and a GROUND. I too vote for PVC in your attic.

03-09-2009, 09:27 AM	#5
sberry Senior Member Join Date: Jun 2005 Location: Brethren, Michigan Posts: 6,847	Re: Conduit In Attic Agreed, this needs an 8 ground wire. __________________ www.urkafarms.com

03-11-2009, 10:52 AM	#6
gdf_77 Member Join Date: Mar 2006 Location: farmersburg, iowa Posts: 54	Re: Conduit In Attic the nec gives a min amount of support for conduit, so in an area where you may be worried about the conduit sagging you can always go above and beyond the minimum. since more than likely your attic won't get near 200 degrees F (90 deg C) derating probably won't be an issue. to be safe you could go to the next size conduit.

03-11-2009, 10:53 AM	#7
gdf_77 Member Join Date: Mar 2006 Location: farmersburg, iowa Posts: 54	Re: Conduit In Attic i too would run pvc.

03-05-2009, 05:01 PM	#1
lenanci Junior Member Join Date: Feb 2008 Location: Phoenix, AZ Posts: 2	Conduit In Attic I'm running 3#4 wires and #10 ground through the attic (70') to a sub panel for my detached garage. I'm getting conflicting information about what kind of conduit to use, PVC or EMT. Obviously PVC would be cheaper but I want it to be safe. The detached garage is permitted in Phoenix, AZ and there will be no inspection in the attic. Code, 2005 NEC. Last edited by lenanci; 03-05-2009 at 07:39 PM. Reason: Added ground and code

03-05-2009, 06:45 PM	#4
walrus Senior Member Join Date: Nov 2008 Location: Maine Posts: 3,670	Re: Conduit In Attic Does Phoenix derate for the extreme heat found in an attic out there? PVC would do the sag thing in that heat??

03-11-2009, 11:07 AM	#8
pipehack Senior Member Join Date: Feb 2009 Location: chicago Posts: 866	Re: Conduit In Attic E.M.T. !!!!!!!! I am very anti P.V.C. strictly because I'm in the trades. If the guy at home depot is so smart then why does he work at home depot.?? Don't take any of their advice seriously.. How much are you really going to save by using P.V.C. ??

03-11-2009, 11:19 PM	#10
lenanci Junior Member Join Date: Feb 2008 Location: Phoenix, AZ Posts: 2	Re: Conduit In Attic I plan on installing 1 1/4" PVC in the attic on top of the roof joists that are 2' OC. 1 1/4" is $3.48 for 10'. EMT is $9.89 for a $10 piece. I need 60'. Big cost difference. Also it would be a major pain to get EMT up there with bends.

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