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 10-25-2010, 04:37 AM   #1
Member
 
Join Date: Nov 2009
Posts: 47
Share |
Default

NM-B 12/2 in metal conduit


I'm running NM-B 12/2 in a crawl space on a 2x6 running board nailed to the floor joists. There's a section of the run where the cable must pass through an opening in the foundation into another crawl space (before it goes up through the floor, into the wall and finally into the attic where it will be jboxed into an existing circuit). It's a rather tight squeeze through this section of foundation (alongside some duct work) and I'd like to use flexible metal conduit in that area (perhaps 2 or 3 feet) to protect the cable.

Am I safe in assuming that it IS acceptable to use flexible metal conduit for a small section like this?

deko is offline   Reply With Quote
Old 10-25-2010, 06:00 AM   #2
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 5,696
Default

NM-B 12/2 in metal conduit


Yes, that is allowed!

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"
jbfan is offline   Reply With Quote
Old 10-25-2010, 08:21 AM   #3
Just call me Andrew
 
Join Date: Mar 2009
Location: Albany, NY
Posts: 2,252
Default

NM-B 12/2 in metal conduit


Does that conduit need to be bonded?
__________________
Andrew

secutanudu is offline   Reply With Quote
Old 10-25-2010, 11:27 AM   #4
Member
 
Join Date: Nov 2009
Posts: 47
Default

NM-B 12/2 in metal conduit


Good question. Do I need to bond the metal conduit in this situation?

Would it be better to use a length of flexible PVC conduit?

250.64(E) Enclosures for Grounding Electrode Conductors Ferrous metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting. Nonferrous metal enclosures shall not be required to be electrically continuous. Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the service equipment and the grounding electrode. The bonding jumper for a grounding electrode conductor raceway or cable armor shall be the same size as, or larger than, the required enclosed grounding electrode conductor. Where a raceway is used as protection for a grounding electrode conductor, the installation shall comply with the requirements of the appropriate raceway article.

Does this code apply to the scenario I described in my original post?

My guess is not because neither end of the run attaches to a metal cabinet or equipment (both ends terminate in plastic boxes) and the grounding conductor in this case remains inside the sheathing.

But I suppose flexible PVC conduit would work just as well for my purposes.

Last edited by deko; 10-25-2010 at 01:05 PM.
deko is offline   Reply With Quote
Old 10-25-2010, 12:52 PM   #5
Member
 
Join Date: Jun 2007
Posts: 3,503
Default

NM-B 12/2 in metal conduit


No, your conduit does need to be bonded and frankly you do not even need the conduit for this application. The NM is a cable and it has its own ground wire (EGC). If you use metal boxes anywhere you must keep this bare grounding wire bonded to the boxes. Metal conduit can serve as the ground in most every circumstance. But a grounding jumper must be installed if you are using any metal boxes.

If this were me, I would not use any conduit unless the cable is subject to damage or will be in a wet or very damp environment. But to answer your question, PVC can be used in lieu of metal.

While your drawing is impressive, it has nothing to do with your application.
J. V. is offline   Reply With Quote
Old 10-25-2010, 01:02 PM   #6
Member
 
Join Date: Nov 2009
Posts: 47
Default

NM-B 12/2 in metal conduit


Thanks for the reply.

My goal is to protect the cable. As I mentioned, there's only a short span, perhaps a few feet, where I want to use conduit. Now that I know a metal conduit requires bonding, I will simply use PVC instead.

deko 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
Connecting metal conduit to ceiling fan junction box tabatt07 Electrical 6 04-26-2010 12:03 AM
Chicago Conduit Rules Wrigleyville Electrical 6 01-28-2010 06:49 PM
Hot tub and metal conduit question kurt9321 Electrical 6 06-23-2009 12:03 PM
Wire size for 300watt trans, 3 way 100ft Al the Diy guy Electrical 16 03-22-2008 08:46 PM
Wire size and type in Rigid Metal Conduit Al the Diy guy Electrical 5 02-05-2008 08:31 PM




Top of Page | View New Posts

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