# Running NM cable in crawlspace along (parallel to) floor joists



## conjectures (Dec 24, 2020)

Hi everyone!

Hoping for some clarification about code and best practices when running NM cable in a crawl space (~1.5' vertical clearance above exposed dirt).

I know that running perpendicular to floor joists requires a running board or running through holes in the joists, but I'm not clear on the requirements when running cable along (parallel to) the floor joists. Is it against code or poor practice to staple cable to the bottom of a joist in that case? It seems to me that this would give the cable similar support and protection to a running board. Does the cable instead need to be run on a side (vertical face) of the joist, at least 1.25" from the bottom edge, as with studs in walls? What are the relevant sections of code?

Any insight is appreciated! Thanks .


----------



## Switched (Dec 23, 2012)

You need to fill out your profile, along with your location if you would like some help.


----------



## varmit (Apr 19, 2009)

In general, you can not attach cables smaller than #4 to the bottom of joists - either parallel or perpendicular. You would usually strap cables at least 1.5 (1 1/4 inch code minimum) 
inches from either joist edge. See NEC 300.4(D)


----------



## emtnut (Mar 1, 2015)

Switched said:


> You need to fill out your profile, along with your location if you would like some help.


Take a minute and fill out yours too buddy 😂


----------



## Switched (Dec 23, 2012)

emtnut said:


> Take a minute and fill out yours too buddy 😂


That better?


----------



## emtnut (Mar 1, 2015)

Switched said:


> That better?


Lol .... Much better 😂


----------



## Kevin (Feb 14, 2017)

@conjectures as the others have said, please take a few minutes to fill out your electrical related field on your profile. It's required.


----------



## conjectures (Dec 24, 2020)

Sorry all, didn't realize that profile info was required! Filled it out now. FYI I'm an electrical engineer in CA, but not an electrician. I am doing some work on my own home's electrical - just running some 12-2 to a few new outlets. 

It sounds like securing the cable on the face of the joist (vertical side) > 1.25" from the bottom edge is the prescribed way to run parallel to a floor joist in the crawl space. What about if you need to get a cable from one side of a single joist to another? Is it ok to wrap a cable under the bottom edge of a joist to get from one vertical face to the other, or is it required to drill a hole in the joist and run the cable through that?

Many thanks again .


----------



## mofos be cray (Nov 14, 2016)

conjectures said:


> Sorry all, didn't realize that profile info was required! Filled it out now. FYI I'm an electrical engineer in CA, but not an electrician. I am doing some work on my own home's electrical - just running some 12-2 to a few new outlets.
> 
> It sounds like securing the cable on the face of the joist (vertical side) > 1.25" from the bottom edge is the prescribed way to run parallel to a floor joist in the crawl space. What about if you need to get a cable from one side of a single joist to another? Is it ok to wrap a cable under the bottom edge of a joist to get from one vertical face to the other, or is it required to drill a hole in the joist and run the cable through that?
> 
> Many thanks again .


Why would you run cable along the bottom edge of a joist? Its a pain in the ****. and if you have move across joist spaces do so along the walls. Or drill. As long as you're not drilling engineered joists


----------



## macmikeman (Jan 23, 2007)

A lot of inspectors would call that a damp location and the nm cable isn't rated damp . You got the license for this kind of work?


----------



## Dennis Alwon (May 9, 2009)

I realize that you can legally work on your own home but the rules here don't allow us to help with diy projecfts even though you are an EE.

Thanks for posting on ElectricianTalk.com. However, working with electricity and electrical systems can be unsafe if not done by a professional licensed electrician. The moderators of this site would like to advise you to contact a professional electrician in your area.If you are permitted by law in your area to do your own electrical work, please sign up at our sister site, www.DIYChatroom.com where many of our professionals are also members and are looking forward to assist you with your needs. Please take a moment to post your question at www.DIYChatroom.com If you're not already a member of DIYChatroom.com you can sign up for a free account by going to http://www.DIYChatroom.com/register.php/


----------

