How to Install Electrical Wiring and Type NM Cable

By - Summary:

How to Install Romex or NM Type Electrical Cable: Common Practices and Methods for Installing Home Electrical Wiring, Beware of Damaged or Defective Electrical Cable, Electrical Cable Bends and Kinks.

Guide to Installing Electrical or Type NM Cable

Electrical Question: Topic: Kinks and bends in Type NM Cable Sheathing.

  • Is having a kink or twist in Type NM Cable a hazard?
  • I have not had an inspector look at the wiring because I always find inspectors to nit pick about little things.
  • Your going to have to bend the wire when it is inside the box anyway?
  • I used the right gauge wire with breaker etc., and staple the wire flat to the joist and studs.
  • If it is wrong can I fix it by taking the 90 degree angle out or do I have to run new wire?
  • I have installed 14 gauge wire with receptacles.
  • Someone mentioned to me that bends in the wire can cause a hot spot.

This electrical wiring question came from: Justin, from Wappingers Falls, New York.

Additional Comments: Nice that you care to help others. Thanks!

Dave’s Reply:
Thanks for your electrical wiring question Justin.

How to Install Type NM Type Electrical Cable


  • Skill Level: Intermediate to Advanced
  • Tools Required: Electricians Pouch of Hand Tools for Rough-In Wiring, Electric Drill and Auger Bits,  Extension Cords, and a Ladder as needed.
  • Safety: All personal safety measures must be taken when performing remodel projects where you may come into contact with hazardous materials and environmental contaminants  such as fiberglass insulation, vermiculite and asbestos, molds or mildew, as well as dust.
  • Estimated Time: Depends on the extent of the project, the type of wall coverings and structural construction and available access to the project area.
  • Precaution: Any existing electrical wiring in the immediate area that may interfere with the installation should be identified and turned OFF and Tagged.
  • Notice: Installing additional electrical wiring or upgrading existing electrical circuits and wiring should always be done according to local and national electrical codes with a permit and be inspected.

 Common Practices and Methods for Installing Type NM Cable for Home Electrical Wiring

Beware of Damaged or Defective Electrical Cable

  • First, lets make sure that this question is not describing damaged cable, so here is what damaged cable looks like: If the insulation has an irregularity or physical damage then it should not be used. This would include rips or tears in the outside sheathing.
  • If the cable has what appears to be a knot inside the cable under the outside sheathing then the cable should not be used. Some of these descriptions may be due to flaws in the manufacturing process which may affect the safety or functionality of the cable.
  • The good news is that this hardly ever is a problem with type NM cable that is manufactured by well known companies, however there have been rare occasions where a bad batch of wire was sent out that had inconsistencies.
  • If defective cable is installed then it could cause a lot of problems which would most likely require the cable to be removed an replaced. During the past 38 years I have seen only a few times where cable had been defective.

Installing NM Type Cable

  • The best way to install NM cable is when the cable is flat which is best accomplished by rolling out the cable like the rolling of a tire or my favorite method is using a stud real which allows the cable to be dispensed from the roll as it is needed.

Electrical Cable Bends and Kinks

  • It is best for the cable to be flat, however if the cable has a few twists it will not hurt.
  • Flat cable makes for easy installation and stapling.
  • The smoother the cable is the easier it is to work with and this makes for a nice neat installation.
  • There should not be any loops or kinks when installing NM cable.
  • I see people on the internet describe loops and even show diagrams showing large loops of cable even right before the entry into a box and this practice can cause problems when the insulation and wall covering is installed which may create a damaged cable.

All electrical wiring projects should be installed with a permit and be inspected by the local building authority.

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Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all projects.


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