Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-18-2008, 03:31 PM   #1
Newbie
 
Join Date: Aug 2008
Posts: 4
Rewards Points: 0
Share |
Default

help a complete newbie with conduit


Hi all, first post here, and limited knowledge on what I'm doing. Here is what I am attempting to do:

My main panel is on the outside of my garage, and currently all wiring for the house goes through the garage (up the studs and along a joist) to the house. All electrical runs through the crawlspace. The garage is not sheetrocked and all wiring is exposed. I'm looking to sheetrock the garage now, but I'm also planning on rewiring the entire house one day (the elctrical is pretty dated). So, I'm thinking of putting in conduit for the future wiring pulls, but don't know what is allowable and how much conduit I need. Any ideas or suggestions is greatly appreciated.

pocketfulladoubles is offline   Reply With Quote
Old 08-18-2008, 03:59 PM   #2
Licensed Electrician
 
jrclen's Avatar
 
Join Date: Feb 2008
Location: central wisconsin
Posts: 982
Rewards Points: 0
Default

help a complete newbie with conduit


Welcome to the forum.

The problem with installing a single conduit for the house circuits is the probable need to de-rate the current carrying capacity of the wires due to having more than 3 in the conduit.

A real life example would be installing 10 circuits in that conduit to the house. That is 20 current carrying conductors in the conduit. These wires then must be de-rated by 50%. A #12 THHN wire would thus be limited to 15 amps. More wires would mean even further reductions. Add the circuits up and count the wires you would need. Each circuit normally has two wires.

If you put 40 current carrying wires in the conduit you would be forced to use #10 wire for a 15 amp circuit. And #8 wire for the 20 amp circuits.

The reductions are:
3 or less = 100 of ampacity
4 to 6 = 80% of ampacity
7 to 9 = 70%
10 to 20 = 50%
21 to 30 = 45%
31 to 40 = 40%
41 or more = 35%

__________________
John

Last edited by jrclen; 08-18-2008 at 04:07 PM. Reason: add more info
jrclen is offline   Reply With Quote
Old 08-18-2008, 05:36 PM   #3
Member
 
Join Date: Jul 2008
Location: Long Island, NY
Posts: 219
Rewards Points: 0
Default

help a complete newbie with conduit


pocketfulladoubles, jrclen speaks wisely. You could cover the "bay" (space between the two joists where the wires run) with a length of plywood (it only needs to be 16" wide) screwed in place and painted the same color as the sheetrock. This way when you need to run new wires, unscrew the plywood, put your new wiring in place, screw the plywood back and you're done. It might be a wise idea to move some of the existing wires further away from the face of the joists to lessen the chances of an errant screw piercing a wire/s.
petey_c is offline   Reply With Quote
Old 08-18-2008, 06:10 PM   #4
Newbie
 
Join Date: Aug 2008
Posts: 4
Rewards Points: 0
Default

help a complete newbie with conduit


Now THAT is a good idea!
Thank you for saving me a lot of time and money...
pocketfulladoubles is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Complete newbie!! Bcharb1331 Introductions 7 04-24-2008 07:09 PM
Conduit Fill & Ampacity capndave Electrical 37 03-26-2008 02:16 PM
Pvc Conduit bobo60 Electrical 1 11-14-2007 09:52 PM
Conduit through basement wall. bdalekid Electrical 13 01-31-2007 08:35 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.