Joe’s original question and comment pertained to romex and bx. The answer given in the electrical class he attended was that neither were acceptable, and that EMT was the proper methodology.
Paul and Greg reflected what I stated in my post. The correct answer is that it depends. I also submit, as does Greg, that an overly damp crawlspace is likely to have several other defects.
Here’s a picture I just found in my library.
That is sure a rats nest of unsecured cables and an orange cord but I don’t see it looking that wet. A properly constructed home should not have a damp crawlspace.
Agreed…if the venting is correct and the crawlspace is taken care of as it should be it should really not be a damp location. In that PIC the floor joists look rather rotten…
Hell…that crawl has more issues than just those hangin cables…
I think the real thing here is application…hard for an AHJ to say the crawl is a damp location…could they…sure but not likely from the inspections and homes we wire and deal with.
Also most homes I see today and that we wire are getting poly vapor barriers put on the crawl floor and so on…making them 100% dry or advertised as such anyway…
Hi to all,
Interesting, as the instructor involved I do not remember stating that, however I do remember class discussion in general of adequate protection of conductors in crawl space locations, and I did invite comment as to the short falls of certain conductor types in damp and damage prone areas.
Joe F, believe nothing of what you hear and only 1/2 of what you see 
Interesting spin 
Gerry
Gerry,
Are you saying that, as the instructor, this was NOT the information provided? THAT would be the most interesting point of this entire discussion!
As to the conditions being damp, I stand by my comments that there are no absolutes, and a determination should be made on-site, and after evaluation. Romex is pretty much unaffected in damp locations (even wet, really. Ad why would a crawlspace be considered a damage-prone area?
So, if you never said that EMT was a preferred methodology in crawlspaces, my apologies. What did you say?
Joe:
I talked to Gerry and we discussed the issues and agreed that what he did say was that it may be recommended that EMT be used if the NM or BX was a problem.
Joe, I am talking about the entire USA and the locations near the seashores and especially around Massachusetts and Boston, the steel stuff just doesn’t last.
Best to do NONMETALLIC in areas where there may be damp or wet location — END OF DISCUSSION!
Joe,
Your question went to romex use, as well. You brought up the EMT.
This may be a slight drift, but while NM is very versatile and wont rust, What about rodents?
I have seen many occasions were Nm and other plastics are chewed by rodents. I have even seen PEX water line fail because a mouse chewed a hole in it.
It seems that many rodents, not only need to chew to ware down their teeth, but have taken a liking to plastics.
I have heard discussions about specific plastic formulas that are more attractive to rodents.
Does anyone feel that this is a problem? Could code change to eventually shield all wiring in open spaces like attics and crawls to protect it from rodents?
lol…I doubt it…NM is just way too popular now days and hell man…if the rodents are getting UP into the floor joists eating PROPERTY supported wires…them are some talented mice…thehehe
Now if it like in the image Joe posted I can see it happening…but less likely if supported correctly…not impossible…just less likely…but heck thats a question for…Steve Irwin…
If you have rats in the crawl space they are in the house and none of your wiring is safe.
I have an 1860’s brick farm house that I completely gutted and re-framed interior walls. I thought I sealed everything well, but I still get mice occasionally. They can get into the smallest holes. I find evidence of mice in new homes during inspections. The worst ones are the subdivisions that carve up farm fields and grass lands. The mice lose their habitat and the homes are nice and warm in winter. They make nest in insulation near wires and then begin to chew.
I found a power vent cord on top of a water heater was stripped of almost all the insulation for 6". The tank had an insulation jacket and is a perfect place to raise a family.
They of course can damage a lot of building materials and the solution is always going to be pest control first. When wiring or plastic pipes are involved the result is water damage or fire. My thoughts were just in reference to how codes evolve and change as repetition of problems occurs and potential risks. I can think of many codes that are in place, yet would occur so rarely, they hardly seem necessary.
Have the electricians in this group seen this often?
I know protecting wiring or using conduit in areas without sealed cavities would be a pain. I would not necessarily want this change but maybe in ten years we will be discussing the new code requirements validity and remembering fondly the days when all you had to do was staple NM.
Just thinking.
AND if they are IN the house…I would MOVE…or call someone to REMOVE them…before they have a chance to do any damage to anything
Aaron,
I am going to be totally honest here…I deal in ALOT of electrical work and quite a fair amount of HI work as well. I just do not see calls of rodent damage to electrical wiring…not to say it is not their and everywhere I just do not see alot of it in my 18 years.
Now with that said I do happen to live in an area in the Shenandoah Valley that has alot of mice, a big difference than RATS…let me say that as I will pick up a mouse…a RAT I am not touching…anyway i also have (4) cats so I feel sorry for the mice in the area…but the RATS would kick my whimpy cats A$$
Ok…I dont know…Greg may have more on this or Bob might but I for the life of me can’t remember speaking to BOB for some time…miss the fella…anyway I just do not see it alot in the way of damage to electrical lines …while again I am sure it happens…to prompt a NEC ( NFPA ) change to reflect that would be hard pressed I am sure…but you never know…rumor has it the AFCI will be spread to all normal areas of the house in the 2008 NEC so anythings possible…
The only rat damage I have seen to wires was in my boat. We did get a dose of roof rats in the house once. The first thing you have to do is find the hole and plug that up. (in my case it was a hole in the soffit under a pan roof)
I trapped 3 and shot 2 before I got them all.
As an inspector I would figure out what rat poo looks like. That will usually be your first indication. When rats are using a hole they will open it up to about 1¼-1½" in diameter.
lol…Rat Poo…Greg our resident Rat Hunter should take a picture of it for us…thehe…Go Rat Hunter…
Go to a pet store and look in trhe Gerbil cage
lol…ahhh…no thanks…Poo is Poo to me…if you seen one rodent POO you seen all the rodents POO…lol
I just wanted to say thanks to the people who contributed to this thread. I had exactly the same question as the one in the opening post.
The guy at home depot (who was very helpful) wasn’t sure that romex was acceptable in a crawl space. He had two issues:
He did say that what I planned to do which was to put the romex inside BX for a short run from the panel to the crawl space isn’t allowed. So now I plan to use individual wires in conduit that connect to a junction box just inside the crawlspace.
As an aside this work is being done on a 1929 building that I own. I have encountered at least 8 different kinds of wire technology in the crawlspace:
The building probably originally had knob and tube but that appears to have been completely removed.
So adding a little modern Romex to this mix, even if it didn’t comply with modern codes, wouldn’t be a big deal but I like the work I do to conform to modern codes even if it is surrounded by work that doesn’t. Also add me to the people who haven’t noticed rodent damaged wires. The building is approaching 80 and that may be the one problem we haven’t had.
Seriously doubt the crawl space was damp or wet at the time the Romex was installed. As someone stated the Romex should not be down on the ground but stapled or secured to the bottoms of the floor joists. Ditto on the Rat comments.