What’s the difference between a heavy duty (12 gauge) extension cord and the 12ga wiring inside the walls of a typical north American home? Why can’t you just chop the ends off and use it to wire up an outlet?
In: 250
Extension cord wires are usually made out of many small strands. Wires in walls are usually made out of single solid wire.
A solid wire can carry more current and performs better than stranded wire of same thickness.
But a solid wire will break if you bend it too many times. Wire made out of small strands is more flexible and can take bending without breaking so easily.
Extension cords need to be flexible, so the wire they use is made up of many different thin strands of wire twisted together. In-wall home wiring is solid copper. The solid conductor can handle much more current than stranded wire at the same guage.
Electrician here. It’s a code violation. An extension cord isn’t designed or listed for permanent use or for being concealed inside walls. Also cutting the ends off would violate the listing for its normal use as an extension cord.
In the US the standard for installation of electrical conductors and equipment is the National Electrical Code. Flexible cords and cables are covered by Article 400 and 400.12 specifically says they shall not be used as a substitute for the fixed wiring of a structure or ran through walls or holes.
Code Violation; Even if the gauge, strand type and purity, and length is the same. The non-conductive material when building has to abide by codes, a very important one is Plenum Rating.
[https://sewelldirect.com/blogs/learning-center/understanding-plenum-and-other-nec-cable-ratings](https://sewelldirect.com/blogs/learning-center/understanding-plenum-and-other-nec-cable-ratings)
Forgot to ELI5: So have you ever thrown plastic in a fire? Sometimes they give off a large amount of smoke, sometimes a little. When you wire things in the wall of your house or business, you will want to make sure if it’s ever on fire, it doesn’t produce a ton of black smoke so the people inside can safely exit. When manufacture’s design products, they usually use the minimum cost solution for nonconductive material. Putting little thought into the safety of it.
The other answers are partly right. Stranded wire isn’t preferred for use in walls but that’s not the main issue. Thicker in-wall wires actually are stranded even though it has disadvantages because solid wire would just be too stiff. The correct answer is it doesn’t meet code, but the *reason* it doesn’t need code is primarily the insulation. In-wall insulation needs to last a very long time and handle a certain level of heat as well as being able to bend and be secured in certain ways without breaking. An extension cord might even meet these requirements but it also needs to be specifically tested and certified and clearly marked so an inspector can tell that the right material was used.
I could be wrong but I feel a big factor (the main?) is longevity of the insulation. Had some old extension cords passed down in the family with rubber insulation peeling off. Granted, it gets flexed and bent, but the whole design is optimized for bending (strands + flexible rubber/plastic) and I think aging is less of a concern. Not sure what the spec is for in-wall wiring but I would hope it’s designed to last 100 years or more.
Well first off, you can technically use it to wire an outlet. The only real difference is that extension cords have many smaller wires as conductors while a cable have one solid conductors. However there may be regulations about whether or not this is allowed.
I’m curious about the inverse, if any of the electricians here can confirm or deny whether you could use wiring designed for internal use as an extension cord? I assume there’s some similar code limitations but curious what exactly they are.
Latest Answers