Wiring from Crawl Space to Outdoor Panel


Old 04-26-07, 11:03 AM
Thread Starter
Join Date: Mar 2007
Posts: 175
Wiring from Crawl Space to Outdoor Panel

I will be running new circuits in the crawl space of the house. The easiest way for me to get back to the main panel (which is located outside) will be to drill a hole in the crawl space siding, then use PVC conduit on the outside to go the two feet up to the bottom of the main panel.

I've been reading that I cannot simply take the NM cable with the outer jacket from the crawl space and stuff it through the conduit up to the main panel (although it is that way with some of the existing circuits). So what's the best way to make the transition to the main panel outside?
Sponsored Links
Old 04-26-07, 03:04 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,803
NM can be run in conduit for short distances to protect the NM.
Old 04-26-07, 03:05 PM
Join Date: Apr 2004
Location: Ontario Canada
Posts: 1,767
Have a large enough JB at the end of the conduit and connect your NM in there. Then run THWN conductors from the JB to the panel
Old 04-29-07, 10:01 PM
Thread Starter
Join Date: Mar 2007
Posts: 175
Wiring Crawl Space to Panel - Derating?

I'm planning to have a junction box at the end of the conduit and connect my 12 gauge NM in there. Then I'll run THWN conductors from the junction box to the panel. A few questions:

1) I believe I can keep the conduit run less than 24". So I don't have to worry about derating, right?

2) Even if I am exempt, are there any good weblinks on derating?

3) I have one remaining knockout on the panel - a concentric with 1/2", 3/4", and 1". I'll probably go with 1" conduit to have room for future expansion. I'm planning on running one green THWN ground wire in this conduit. Is there a limit to the number of circuits than can share this ground?
Old 04-30-07, 10:35 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,337
1) Conduit 24" or less is exempt from derating.

2) Not really.

3) All circuits in the conduit may share the ground wire. The ground should be sized to match the largest circuit in the conduit (#14 for 15A, #12 for 20A, #10 for 30A to 60A).

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

Thread Tools
Search this Thread
Display Modes