Ribbed Wire To Black Or White

How to identify & wire the hot, neutral, & ground wires on a wall plug or line cord plug (C) Daniel Friedman at InspectApedia.com

Electrical Wall Plug Wire ID & Connections
How to identify the hot, neutral, ground wires in an lamp cord, appliance cord, or other electrical cord wall plugs

How to identify the hot & neutral wires by color, by ribbing on the zip cord or lamp cord, or by a white strip on the zip cord or lamp cord to be sure that your wall plug is wired properly.

Watch out : mis-wired electrical wall plugs or any other electrical wiring is dangerous, risking fire or shock or even death. Electrical wiring should be performed by a licensed, trained electrician and should comply with the National Electrical Code and local regulations. This article series describes how to choose, locate, and wire an electrical receptacle in a home.

We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Electrical Wire Identification at a wall plug or line cord

Line cord switch wiring detail: which wire is connected to the switch ? (C) Daniel Friedman at InspectApedia.com - answer: the ribbed-insulation identifies the un-switched neutral wire. Switch the hot wire.

How do we know which wire in a line cord should be wired to the neutral or wide-space of a wall plug?

Why is knowing this detail important? Here we answer those questions. Photo: a add-on line cord switch used to turn a bedside lamp on and off should be wired so that the switch interrupts the hot wire, not the neutral wire.

Our page top illustration shows an un-grounded lamp cord wall plug connected to an electrical receptacle.

Older non-polarized wall plugs may have just two connecting spades, each the same size. Still you can easily identify which wire is the "hot" and which is the "neutral" in these line cords and wall plugs by observing any of several indicators we list below.

If the plug is not a polarized model, why should you care which wall plug is hot and which is neutral? After all, our building’s electrical circuits are mostly 120VAC or 240VAC – where "AC" means "alternating current".

An electrical device will "work" regardless of which way the plug is inserted.

The answer is that some electrical devices are unsafe if polarity is reversed. Some of the hazards are subtle. Here are examples:

such as the igniter circuit of a gas cooktop or range, reversed polarity can cause an electric shock on touching the igniter or burner top even when the burner is "off" – see details in reader comments found

Details about the hazards of reversed polarity are

[Click to enlarge any image]

How to Identify the Hot and Neutral Wires in a Line Cord or "Zip Cord" Wire

Look for any of the following:

Ribbed side of line cord idenifies the neutral or 'white' or wide-plug-spade wire (C) Daniel Friedman at InspectApedia.com

of the line cord indicates the neutral wire, the smooth side, the hot wire.

If we are wiring a line cord plug, the ribbed wire would connect to the wider space or neutral space on the plug itself.

If we are wiring a line cord switch such as shown in our photo, we take care that the switch interrupts the "hot" or smooth wire.

Ribbing along the length of one side of a line cord or zip cord wire marks the neutral wire (C) Daniel Friedman at InspectApedia.com

Below: white stripe indicates the neutral wire in this line cord.

White strip on line cord indicates the neutral wire (C) Daniel Friedman at InspectApedia.com

A near-transparent lamp cord used to operate a table lamp provides an example of identification of the neutral wire by noticing that the neutral wire is silver while the hot or "line" wire is copper colored.

    If the line cord is transparent

Really? Not always. As we illustrate below, some clear or translucent line cords will use two copper-colored wires, and others may use two silver-colored wires.

In that case you should expect one side of that line cord to bear ribs along the length of the neutral wire.

Ribbing on clear lamp cord wire insulation indicates the neutral wire (C) Daniel Friedman at InspectApedia.com

    The wider spade of the wall plug

Grounded wall plugs will only insert into the the wall electrical receptacle one-way, the proper way (C) Daniel Friedman at InspectApedia.com

    A wall plug that includes a ground prong

Shown earlier on this page (discussing use of a white stripe to mark the neutral wire), this particular grounded line-cord plug does not sport connector-spades of different widths; both are the same, but as we illustrate above, it is impossible to insert this plug incorrectly into the wall receptacle.

Below: we illustrate that not all electrical receptacles and line cord plugs require polarity.

Non-polarized 240VAC line voltage cord plug and wall receptacle in Venice, Italy (C) Daniel Friedman at InspectApedia.com

    Non-Polarized Wall Plugs & Receptacles

include this 240VAC electrical outlet and line cord plug in use in an apartment in Venice, Italy.

Continue reading at ELECTRICAL OUTLET, HOW TO ADD & WIRE – home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Electrical Receptacle Wiring Articles


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Technical Reviewers & References

  • Timothy Hemm has provided photographs of various electrical defects used at the Inspect A Pedia TM Website. Mr. Hemm is a professional electrical inspector in Yucala, CA.
  • Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 [email protected]
  • John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-873-8534 or by Email: [email protected]
  • [3] NFPA – the National Fire Protection Association can be found online at www.nfpa.org
  • [4] The 2008 NEC National Electrical Code (ISBN 978-0877657903) Online Access LINK (you’ll need to sign in as a professional or as a visitor)
  • [5] Special thanks to our reader Steve who pointed out prior errors in our illustrations.
  • [6] Simpson Strong-Tie, "Code Compliant Repair and Protection Guide for the Installation of Utilities in Wood Frame Construction", web search 5/21/12, original source strongtie.com/ftp/fliers/F-REPRPROTECT09.pdf, [copy on file as /Structures/Framing/Simpson_Framing_Protectors.pdf ]. "The information in this guide is a summary of requirements from the 2003, 2006 and 2009 International Residential Code (IRC), International Building Code (IBC), International Plumbing Code (IPC), International Mechanical Code (IMC), 2006 Uniform Plumbing Code (UPC) and the 2005 National Electrical Code."
  • "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
  • "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
  • "How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
  • "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
  • "Home Wiring Inspection," Roswell W. Ard, Rodale’s New Shelter, July/August, 1985 p. 35-40.
  • "Evaluating Wiring in Older Minnesota Homes," Agricultural Extension Service, University of Minnesota, St. Paul, Minnesota 55108.
  • "Electrical Systems," A Training Manual for Home Inspectors, Alfred L. Alk, American Society of Home Inspectors (ASHI), 1987, available from ASHI. [DF NOTE: I do NOT recommend this obsolete publication, though it was cited in the original Journal article as it contains unsafe inaccuracies]
  • "Basic Housing Inspection," US DHEW, S352.75 U48, p.144, out of print, but is available in most state libraries.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews – InspectAPedia.
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