Permitted types of wiring methods

Originally Posted By: jtedesco
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Question:


Can I use Type NM cables to wire my new addition, and to rewire my basement?

I just bought a roll of 12/2/W/Ground at the Flea market here in town for $30.00.

Note:

My existing cables are of the older types with green, and some silver outer covering and with no bare wire for grounding!!


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: jmyers
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Joe T,


Well yes, you can use type NM cable to rewire your basement and for the addition, unless local codes would prohibit it, such as in Chicago! ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)

Why do you ask?


--
Joe Myers
A & N Inspections, Inc.
http://anii.biz

Originally Posted By: jtedesco
This post was automatically imported from our archived forum.



Joe


Even if it had Type TW 60 degree insulation?


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: Greg Fretwell
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Other than derating issues or attachment to some identified ceiling luminaires, NM and NM-b are essentially equal. Why couldn’t you use it? I would have greater concerns if you would be extending ungrounded circuits.


Originally Posted By: dbowers
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Sure Joe, just do it the way all homeowners do it - safely & properly…


Originally Posted By: jtedesco
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icon_biggrin.gif


Quote:
PWVX.Guide-Info

Nonmetallic-sheathed Cable

USE

This category covers Types NM-B and NMC-B nonmetallic-sheathed cable, rated 600 V, intended for use in accordance with Article 334 of ANSI/NFPA 70, "National Electrical Code" (NEC), and Listed in copper sizes 14 to 2 AWG inclusive and aluminum or copper-clad aluminum sizes 12 to 2 AWG inclusive.

This cable contains conductors rated 90?C; however, the ampacities of the cable are those of 60?C conductors as specified in Article 334 and Table 310.16 of the NEC.

PRODUCT MARKINGS

Cable with copper-clad aluminum conductors is surface marked "AL (CU-CLAD)" or "Cu-clad Al," and cable with aluminum conductors is surface marked "AL."

Wire and cable employing compact-stranded copper conductors is so identified directly following the conductor size, wherever it appears (surface, tag, carton or reel), by "compact copper." The abbreviations "CMPCT" and "CU" may be used for compact and copper, respectively.

Tags, reels and cartons for products employing compact-stranded copper conductors have the marking: "Terminate with connectors identified for use with compact-stranded copper conductors."

Cable suitable for use in cable trays is appropriately marked. Cable marked for cable tray use may also have a supplementary sunlight resistant marking.

Cable that complies with the Limited Smoke Test requirements specified in UL 1685, "Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables," is surface marked with the suffix "LS."

ADDITIONAL INFORMATION

For additional information, see Electrical Equipment for Use in Ordinary Locations (AALZ).

REQUIREMENTS

The basic standard used to investigate products in this category is UL 719, "Nonmetallic-Sheathed Cables."

UL MARK

The UL symbol on the product and the Listing Mark of Underwriters Laboratories Inc. on the attached tag, coil, reel or smallest unit container in which the product is packaged is the only method provided by UL to identify these products manufactured under its Listing and Follow-Up Service. The Listing Mark for these products includes the UL symbol (as illustrated in the Introduction of this Directory) together with the word "LISTED," a control number, and the product name as appropriate: Nonmetallic-sheathed cable that contains copper or copper-clad aluminum conductors has the product name "Nonmetallic-sheathed Cable"; nonmetallic-sheathed cable that contains aluminum conductors has the product name "Nonmetallic-sheathed Aluminum Cable."

Last Updated on 2001-11-26

This page and all contents are Copyright ? 2005 by Underwriters Laboratories Inc.?

The appearance of a company's name or product in this database does not in itself assure that products so identified have been manufactured under UL's Follow-Up Service. Only those products bearing the UL Mark should be considered to be Listed and covered under UL's Follow-Up Service. Always look for the Mark on the product.

UL permits the reproduction of the material contained in the Online Certification Directory subject to the following conditions: 1. The Guide Information, Designs and/or Listings (files) must be presented in their entirety and in a non-misleading manner, without any manipulation of the data (or drawings). 2. The statement "Reprinted from the Online Certifications Directory with permission from Underwriters Laboratories Inc." must appear adjacent to the extracted material. In addition, the reprinted material must include a copyright notice in the following format: "Copyright ? 2005 Underwriters Laboratories Inc.?"


Type NM was used before the change in 1984 to require the higher rated insulation.

My point was missed! Again, I expected to see where the designation NM as I described was the reason to reject the installation.

How many Home Inspectors look for new installations in existing building and find the old type used?

I cannot approve any installation that uses the old Type NM cable, it was only rated as 60 degree c and was TW insulation.




--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: dbowers
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Joe -


What exactly did you say without all the quotation marks, etc.


Originally Posted By: Greg Fretwell
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Again I ask how you can fail it. If they are not derating in the 75 or 90c column and there is no equipment labelled “90c only” why is TW not an acceptible conductor type? Did NM lose it’s listing when the NM-b was listed?


334.6 Listed.
Type NM, Type NMC, and Type NMS cables shall be listed.


Don't look like the NEC noticed ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


Originally Posted By: jtedesco
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Greg Fretwell wrote:
Again I ask how you can fail it. If they are not derating in the 75 or 90c column and there is no equipment labelled "90c only" why is TW not an acceptible conductor type? Did NM lose it's listing when the NM-b was listed?

334.6 Listed.

Type NM, Type NMC, and Type NMS cables shall be listed.

Don't look like the NEC noticed ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


Here's the rest of the story Greg:

Quote:
334.112 Insulation. The insulated power conductors shall be
one of the types listed in Table 310.13 that are suitable for
branch circuit wiring or one that is identified for use in these
cables.

Conductor insulation shall be rated at 90?C (194?F).

FPN: Types NM, NMC, and NMS cable identified by the
markings NM-B, NMC-B, and NMS-B meet this requirement.



--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: jtedesco
This post was automatically imported from our archived forum.



dbowers wrote:
Joe -

What exactly did you say without all the quotation marks, etc.


See the UL directory www.ul.com and search for PWVX.

I did not add any quotations! ![icon_rolleyes.gif](upload://iqxt7ABYC2TEBomNkCmZARIrQr6.gif)

Maybe someone will send you the PDF file of the directory.


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: Greg Fretwell
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I do see where you are coming from.


That becomes a slippery slope. Are you saying, if the scope of a renovation requires bringing the structure up to current code you would have to remove all of the NM?


In the grand scheme of homeowner inflicted hazards I rate this pretty low.


Originally Posted By: jtedesco
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Greg:


OK, My intention was to describe the Type of wiring method that is no longer permitted because of situations in ceilings and other areas around homes where the heat in the attic, for example, was enough to breakdown the old TW 60 C insulation.

I have the TCR and TCD report and substantiation that was submitted with the proposal for the change that was accepted in the 1984 NEC.

As far as your question, I would recommend an inspection of the existing cables to find out if the conductor insulation showed sign of being brittle.


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: Greg Fretwell
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I agree there are problems when you install TW type conductors in environments where they will experience greater than the rated 60c (140f) but if that is avoided type TW is still a safe wire and is still listed.


Originally Posted By: roconnor
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jtedesco wrote:
Can I use Type NM cables to wire my new addition, and to rewire my basement?

Possibly

I would say it should be the newer type NM-B with the 90C insulation, unless the AHJ approves the use of the older type NM with the 60C insulation since it's in a basement not likely to be subject to excessive heat.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jtedesco
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Thanks for your opinion Bob, that would be one of the solutions — with a disclaimer for the records.


Do you think that the HI should make any comments if the product was installed after 1984?

![icon_question.gif](upload://t2zemjDOQRADd4xSC3xOot86t0m.gif)


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: jmyers
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Joe T,


Sorry for the assumption on my part, I did assume you were talking about a 1,000 foot roll of NM-B, not the older NM cable.

From a home inspectors point of view, I would not check the types of cable that are used for the installation. It would be well beyond the scope of a home inspection and would add considerable length and cost to the inspection.

Now, if I was performing electrical work on this home, I would be able to check the condition of the cable while making connections and based on the condition of the cable at the time, if it needed to be replaced because of fragile insulation, I would certainly notify the owner and I would also instruct them on the hazards of, "doing nothing".

To further the problem, many of the states townships did not require adherence to any codes at all, until the state mandated it a few years ago, so the information about when it was installed would only be available if the seller would relinquish that information voluntarily, or the buyer themselves would try to obtain that information from the township in which the home is located.


--
Joe Myers
A & N Inspections, Inc.
http://anii.biz

Originally Posted By: jtedesco
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OK


Stay safe!

![](upload://fBoHIH4EYaFYLPAFs2JR1PwPqLF.gif)


--
Joe Tedesco, NEC Consultant

www.nachi.org/tedescobook.htm

Originally Posted By: roconnor
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jtedesco wrote:
Do you think that the HI should make any comments if the product was installed after 1984?

I think it would be good for HI's to be aware of the change in the "industry construction standards" (aka model codes) and be on the lookout for any possible visible signs of potential defects and concerns.

I understand one of the big reasons for the switch to the 90C insulation (while still using the lower 60C wire ampacities) was to simplify or negate any possible derating of typical residential sheathed cable with heavy loads in warmer areas of a home where it might be a concern. That doesn't mean ya couldn't make it work if calculated out ... but that is well beyond a home inspection.

Just my opinions and 2-nickels ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong