Use of Flexible Non Metallic Conduit Inside

[automatikdonn]

I am looking for the legal answer on whether or not flexible non-metallic conduit is legal to use inside a structure. I have found 1 thread that discusses this. It was stated it's up to the jurisdiction. In my experience local jurisdictions just point back to NEC, but I am surely no pro. (Hence why I ask)

I have also searched on Mike Holt and seen the same sort of response, however there are no citations. Is this because of "this is how we have always done it" syndrome or is this legit.

Does anyone have a local jurisdiction code that prohibits use of Flexible NMC?

I understand that I could just Google it myself, but the power of community is that someone else probably has this answer and relevant info off the top of their head.


Thanks for any responses

 

[Kornbread]

We use a lot of Sealtight in the factory. With frequent inspections, if it wasn't up to code, it wouldn't be there. It is possible residential may be different.

 

[Mattb4]

The best answer is to call up your local code enforcer and ask, "Can I use Flexible NMC?"

 

[timselectric]

It depends on what you are using it for.
For AC circuits it's fine, as long as you install a ground conductor with the circuit conductors.
Also fine for DC power circuits.
But not allowed for PV circuits. Those have to be in metal conduit. (Flexible is ok)

 

[HRTKD]

But not allowed for PV circuits. Those have to be in metal conduit. (Flexible is ok)

Why is PV different? Just curious.

 

[timselectric]

Why is PV different? Just curious.

I'm sure that I knew the answer, at some point.
But, it's alluding me, at the moment.
It's probably because it's an ungrounded power source. But, don't quote me on that.

 

[Ampster]

Perhaps the likelihood that the voltage could be high for PV wires?

 

[timselectric]

Perhaps the likelihood that the voltage could be high for PV wires?

It's definitely due to the high Hazzard it provides.
Just can't remember the exact specifics.
And can't remember who it was that told me.
An old brain isn't the best place to keep important information. lol

 

[Hedges]

Not sure about code/legality.
I'd be concerned about toxic fumes. How about using flexible metallic instead?

https://www.hunker.com/13401358/what-are-the-dangers-of-heating-a-pvc-pipe

Voltage of PV isn't particularly higher than 277/480Y.
I think main difference is if there is a fault, it often doesn't trip a breaker and just maintains an arc. (with EMT, will probably burn through the metal, not much better than plastic.)

 

[Northernchateau]

We use a lot of Sealtight in the factory. With frequent inspections, if it wasn't up to code, it wouldn't be there. It is possible residential may be different.

Sealtight is I remember has a metal core. I used Carlon electrical nonmetallic tubing and it made the installation easy and clean.

 

[JJJJ]

Is it possible that for Dc the current is constant vs ac that is alternating?

 

[Shimmy]

352.10 Uses Permitted. The use of PVC conduit shall he permitted in accordance with 352.10(A) through (I).
Informational Note: Extreme cold may cause some nonmetallic conduits to become brittle and, dierefbre, more susceptible to damage from physical contact
(A) Concealed. PVC conduit shall be permitted in walls, floors, and ceilings.
(B) Corrosive Influences. PVC conduit shall be permitted in locations subject to severe corrosive influences as covered in 300.6 and where subject to chemicals for which the materials are specifically approved.
(C) Cinders. PVC conduit shall be permitted in cinder fill.
(D) Wet Locations. PVC conduit shall be permitted in portions of dairies, laundries, canneries, or other wet locations, and in locations where walls are frequently washed, the entire conduit system, including boxes and fittings used therewith, shall be installed and equipped so as to prevent water from entering the conduit. All supports, bolts, straps, screws, and so forth, shall be of corrosion-resistant materials or be protected against corrosion by approved corrosion-resistant materials.
(E) Dry and Damp Locations. PVC conduit shall be permitted for use in dry and damp locations not prohibited by 352.12.
(F) Exposed. PVC conduit shall be permitted for exposed work. PVC conduit used exposed in areas of physical damage shall be identified for the use.
Informational Note: PVC Conduit, Type Schedule 80, is identi- fied for areas of physical damage.
(G) Underground Installations. For underground installa- tions, PVC shall be permitted for direct burial and under- ground encased in concrete. See 300.5 and 300.50.

352.12 Uses Not Permitted. PVC conduit shall not be used under the conditions specified in 352.12(A) through (E).
(A) Hazardous (Classified) Locations. In any hazardous (clas- sified) location, except as permitted by other articles of this Code.
(B) Support of Luminaires. For the support of luminaires or other equipment not described in 352.10(H).
(C) Physical Damage. Where subject to physical damage unless identified for such use.
(D) Ambient Temperatures. Where subject to ambient temperatures in excess of 50°C (122°F) unless listed otherwise.
(E) Theaters and Similar Locations. In theaters and similar locations, except as provided in 518.4 and 520.5.

Generally Flexible Nonmetallic Conduit is not acceptable unless movement is required, although most inspectors will allow short lengths under 6'.

 

[Solar Guppy]

Why is PV different? Just curious.

PV energy is not regulated / switched from the roof, IE if there is Sun, there is energy which if there is a short inside the conduit, there will be flames/fire that cannot be extinguished and with plastic will burn through the conduit, then the home potentially.

 

[Ampster]

An old brain isn't the best place to keep important information. lol

I try not to keep anything in my old brain that I can look up on my phone or the Internet.

 

[timselectric]

I try not to keep anything in my old brain that I can look up on my phone or the Internet.

Same here. But I can't remember if I have accomplished it. lol

 

[rhino]

For AC circuits it's fine, as long as you install a ground conductor with the circuit conductors.

Still depends on where you are. Chicago and surrounding area is extremely strict and you have to have everything in rigid metal conduit. No exposed cables. They recently allowed flexible metal conduit in some cases but I'm not sure if that is even allowed in new construction still.

 

[timselectric]

Still depends on where you are. Chicago and surrounding area is extremely strict and you have to have everything in rigid metal conduit. No exposed cables. They recently allowed flexible metal conduit in some cases but I'm not sure if that is even allowed in new construction still.

I believe that New York is just as bad.
And possibly Florida.

 

[740GLE]

PV energy is not regulated / switched from the roof, IE if there is Sun, there is energy which if there is a short inside the conduit, there will be flames/fire that cannot be extinguished and with plastic will burn through the conduit, then the home potentially.

Depends, for on grid sure, but many small off grid set ups could have a combiner box with OCP near the array and a home run to the SCC, or in line fuses near the array.

Each site is different.

 

[justgary]

I believe that New York is just as bad.
And possibly Florida.

Please don't ever put Florida in any group with Chicago or New York.

 

[fromport]

Still depends on where you are. Chicago and surrounding area is extremely strict and you have to have everything in rigid metal conduit. No exposed cables. They recently allowed flexible metal conduit in some cases but I'm not sure if that is even allowed in new construction still.

In my neck of the woods in California it is rigid metal conduit for everything outside.
In eg attics (protected space) they allow flexible metal conduit

 

[Shimmy]

In my neck of the woods in California it is rigid metal conduit for everything outside.
In eg attics (protected space) they allow flexible metal conduit

Rigid metal conduit or just metal conduit (EMT)?

 

[automatikdonn]

Can anyone link those regulations for the relevant locations. I think it would make this easier for people to look up and probably be more searchable so dummies like me won't ask this question again.

 

[timselectric]

Can anyone link those regulations for the relevant locations. I think it would make this easier for people to look up and probably be more searchable so dummies like me won't ask this question again.

Some of it is based on the interpretation of the local inspector. So, it's best to check with them before starting a project.

 

[fromport]

Rigid metal conduit or just metal conduit (EMT)?

EMT. i copied the line from the person I replied to. sorry

 

[Ampster]

Can anyone link those regulations for the relevant locations. I think it would make this easier for people to look up and probably be more searchable so dummies like me won't ask this question again.

There are fifty states and within each state as many as a hundred jurisdictions. Some of those may not be online so the earlier suggestion to call your local inspector probably is the most optimal.