nm cable in pvc

Status
Not open for further replies.
iwire said:
Please cite the code section you believe requires that.
Click to expand...
How about the marking requirements in 310.120?

Most if not all NM cable has no markings on individual conductors, once you strip the sheath off you are left with a conductor that doesn't comply with 310.120 at the very least, if left within the sheath, the sheath is marked to comply with 310.120.
 
iwire said:
Please cite the code section you believe requires that.
Click to expand...
110.3 (B)....;)

Also keeping in mind that all manufacturers of NM-B do not mark our inner conductors because UL 719 permits this. The required markings are on the cable sheathing.

Comments based on the 2017 National Electrical Code.
 
Who is yall....they made it long before I came. But I will tell you as for the sheathing it's the same PVC...just with less additives needed for insulation since NM-B location use is limited....about all I can tell you without special handshakes and security clearances.;)

The insulation itself on the wire are exactly equivalent to THHN without the markings or nylon covering . However, nothing prevents us from using normal THHN with markings...but why...ink is expensive.

Comments based on the 2017 National Electrical Code.
 
kwired said:
How about the marking requirements in 310.120?

Most if not all NM cable has no markings on individual conductors, once you strip the sheath off you are left with a conductor that doesn't comply with 310.120 at the very least, if left within the sheath, the sheath is marked to comply with 310.120.
Click to expand...
So you cannot tell at the junction box or transition the conductors in the conduit are the same conductors of the cable assembly. :lol:
 
MasterTheNEC said:
Who is yall....they made it long before I came. But I will tell you as for the sheathing it's the same PVC...just with less additives needed for insulation since NM-B location use is limited....about all I can tell you without special handshakes and security clearances.;)

The insulation itself on the wire are exactly equivalent to THHN without the markings or nylon covering . However, nothing prevents us from using normal THHN with markings...but why...ink is expensive.

Comments based on the 2017 National Electrical Code.
Click to expand...

I was poking fun at all the people that claim to know what the insulation is. Not actually directed at you.

Some say THHN and some say THWN, some swear they know.

I say who cares. The NEC says it is simply a 90C conductor limited to 60C for final ampacity. That works for me.
 
jumper said:
I was poking fun at all the people that claim to know what the insulation is. Not actually directed at you.

Some say THHN and some say THWN, some swear they know.

I say who cares. The NEC says it is simply a 90C conductor limited to 60C for final ampacity. That works for me.
Click to expand...
I can understand that....Agreed. But now they know...lol...or they could just read UL 719 and really know...lol.

Truth is some do just use THHN and retain the nylon, just don't mark it or they remove the nylon, increase the thickness and meet TW equivalent as well.

6 Insulation

6.1 Both before and after assembly into finished cable, the insulation employed on the circuit conductors shall comply with (a) or (b):

a) THHN Construction – Jacketed insulation for a Type NM or NMC cable shall have a nylon or similar jacket and shall comply with the thickness and other applicable requirements for Type THHN thermoplastic-insulated wire without (see 25.18) any surface marking of ″THHN″, ″-B″, or any ampacity or temperature rating.

b) TW Construction – Insulation without a nylon jacket shall comply with the thickness requirements for a Type TW thermoplastic-insulated wire. The insulation material shall comply with (1) or (2):

1) For TYPE NM or Type NMC Cable – The insulation material shall be a dry-locations PVC that complies with the requirements for Type THHN insulation without any surface marking of the ampacity or temperature rating (the surface marking ″-B″ is optional on the insulation). The tensile strength and elongation are to comply with Table 50.155 of UL 1581. The deformation test is to be conducted at 121.0 ±1.0°C (249.8±1.8°F) with a decrease of not more than 50 percent in the thickness of the PVC insulation.

2) For TYPE NM only – Type NM is eligible to use a thermoplastic insulating material other than PVC. The performance and ratings of the material as insulation shall be determined by investigation and shall be:

i) Electrically comparable to the PVC insulation in Type THHN wire, and

ii) Mechanically comparable to the nylon or similarly jacketed PVC insulation of Type THHN wire, and

iii) In accordance with Table 50.144 of UL 1581.

Comments based on the 2017 National Electrical Code.
 
kwired said:
I can, NEC says I can't:p
Click to expand...
Where? :huh:

The required markings are on the sheath. The conductors in the conduit are the same as contained within the sheath. Code does not stipulate the markings must be over the entire length of the assembly.
 
kwired said:
How about the marking requirements in 310.120?

Most if not all NM cable has no markings on individual conductors, once you strip the sheath off you are left with a conductor that doesn't comply with 310.120 at the very least, if left within the sheath, the sheath is marked to comply with 310.120.
Click to expand...

You mean this 310.120?

The 310.120 found in Part III Construction Specifications of article 310?

310.120 Marking.
(A) Required Information. All conductors and cables
shall be marked to indicate the following information, using
the applicable method described in 310.120(B):

(1) The maximum rated voltage.

(2) The proper type letter or letters for the type of wire or
cable as specified elsewhere in this Code.

(3) The manufacturer's name, trademark, or other distinctive
marking by which the organization responsible for
the product can be readily identified.

(4) The AWG size or circular mil area.
Informational Note: See Conductor Properties, Table 8 of
Chapter 9, for conductor area expressed in SI units for
conductor sizes specified in AWG or circular mil area.

(S) Cable assemblies where the neutral conductor is
smaller than the ungrounded conductors shall be so
marked
Click to expand...

First issue I have with that is I do not construct wire and cable, I install it. That section is aimed at manufacturers not the end user.

Second issue, if in fact that section means what many feel it means where is the permission to remove that marking when entering an enclosure?
 
iwire said:
You mean this 310.120?

The 310.120 found in Part III Construction Specifications of article 310?



First issue I have with that is I do not construct wire and cable, I install it. That section is aimed at manufacturers not the end user.

Second issue, if in fact that section means what many feel it means where is the permission to remove that marking when entering an enclosure?
Click to expand...

right it is construction requirements. Stripping sheath off and pulling the remaining conductors is de-constructing something that originally met the construction requirements.
 
kwired said:
right it is construction requirements. Stripping sheath off and pulling the remaining conductors is de-constructing something that originally met the construction requirements.
Click to expand...

You are kidding me now right?

Because you cannot possibly be serious with that response. :huh:
 
From a manufacturers perspective we install the sheathing on Type NM-B for it to remain in place until which time it enters an enclosure or junction point or similarly terminated in some fashion. We can't say the same thing for Type MC Cable because we put the markings on those inner conductors and allow transitions (with proper fittings) from MC to other wiring methods like EMT and so on. We mark those inner(s) because we support that transition.

On the construction thing...to be honest the UL standards are for our use in constructing the product and we leave the NEC do the installation aspects of it. However, we fall back on those construction standards when it comes to NEC 110.3(B) and how our products (speaking for the manufactures if I may) are installed. We have no problem with NM-B being installed in accordance with Article 334 and would support such efforts. We can't however support things that are outside of our expectation of the products use. We understand that once you buy it that it's yours and you can do anything you want with it but in terms of respecting any warranty (which is usually only a year) we will always fall on the intended use of a product we sell.

Building wire has to conform to the UL Standards or we can't sell it so when we sell you type NM-B cable we expect it to be used whole until which time you enter an enclosure and terminate it. Interesting to note we also have no issued with Type NM-B in RMC for use in Type I or II construction as long as the sheathing is intact. All wires are again required to me marked if they are to be used outide of their wiring methods to which they are constructed.

Just my thoughts on that subject...
 
iwire said:
You are kidding me now right?

Because you cannot possibly be serious with that response. :huh:
Click to expand...
I'd say I was partly kidding yet partly serious.

Strip the sheath off and what are you left with to be able to identify the conductors as something acceptable for use by NEC? Right after you remove conductors from sheath you knew what they come from. Bring in a third party that had nothing to do with the install and how do they know if it is THHN, THWN, TFFN, MTW, etc. or if it is even a conductor permitted by NEC.
 
kwired said:
I'd say I was partly kidding yet partly serious.

Strip the sheath off and what are you left with to be able to identify the conductors as something acceptable for use by NEC? Right after you remove conductors from sheath you knew what they come from. Bring in a third party that had nothing to do with the install and how do they know if it is THHN, THWN, TFFN, MTW, etc. or if it is even a conductor permitted by NEC.
Click to expand...
:thumbsup:
Whereas if you strip the sheath at the boundary of a box, leaving even a bit inside, it should be clear what the conductors are part of.
 
GoldDigger said:
:thumbsup:
Whereas if you strip the sheath at the boundary of a box, leaving even a bit inside, it should be clear what the conductors are part of.
Click to expand...
Out of all the thousands, if not millions of miles of wires I've pulled and terminated, do you know how many I've checked the type of wire after pulling it?
 
kwired said:
Strip the sheath off and what are you left with to be able to identify the conductors as something acceptable for use by NEC? Right after you remove conductors from sheath you knew what they come from. Bring in a third party that had nothing to do with the install and how do they know if it is THHN, THWN, TFFN, MTW, etc. or if it is even a conductor permitted by NEC.
Click to expand...

I am dying to hear how what you describe is any different when striping NM to enter a panel vs striping NM to enter a conduit.

GoldDigger said:
:thumbsup:
Whereas if you strip the sheath at the boundary of a box, leaving even a bit inside, it should be clear what the conductors are part of.
Click to expand...

Hold on, the argument was the sheath has to remain because the identification has to remain.

You cannot see the labeling inside a box in either direct cable entery or cable entry via a conduit.
 
Status
Not open for further replies.
Top