Re: Big oops ... need suggestions
From the Author: This has been a very interesting discussion. Thanks to everyone that took part in this and several other threads that discuss the issues raised by applying the requirements of the 2005 NEC 210.12 to real world wiring. I have learned a lot from all who participated.
The background that I bring with me to this discussion is, in part, informed by being a one person electrical contracting business owner, by being a working (hands on the tools) Minnesota Master Electrician, by holding a Bachelor of Science in Electrical Engineering, and by text editing for the past eighteen years (resulting in my position as Senior Technical Electrical Consultant for several books and two ongoing monthly magazines).
How the NEC? Article 100 Definition of Premises Wiring (System) defines an Outlet in a Switch used as a Controller,
Introduction.
My motivation in articulating what I have come to understand the meaning of Outlet, and Premises Wiring (System), to be is simple: we need to talk about it. The hardware one may install in dwelling bedroom switch locations, occasionally, is obviously utilization equipment in its own right, or, has obvious components that, by themselves, would be utilization equipment. When this hardware is discussed in a community of peers, diverse opinions are expressed, some cogently, some dogmatically, some with deliberate obfuscation. The status quo is that, no matter what goes on in the hardware that is used as a switch, "The hardware is a switch, not an outlet." This has been stated in many ways. The contradiction of the hardware in my hand that, in part, is a switch, has been impossible for me to ignore. I decided to speak out. Using the language of the NEC itself, I have come to defend as a cohesive whole an interpretation of:</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">210.12 Arc-Fault Circuit-Interrupter Protection</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Art. 100 Outlet</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Art. 100 Controller</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Art. 100 Premises Wiring (System)</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">404.14 Rating and Use of Snap Switches.</font>
<font size="2" face="Verdana, Helvetica, sans-serif">
My comments below are specifically bearing in mind a bedroom switch on a 15 or 20 Amp 120 Volt branch circuit controlling an outlet outside the bedroom. 2002 and 2005 NEC 210.12 is pretty straight forward and unambiguous in its requirement that all 15 and 20 Amp 120 Volt branch circuits supplying outlets in bedrooms must have Arc-Fault Circuit-Interrupters (AFCIs). Applying 210.12 requires an agreement on the definition of the term "outlet".
I contend that the definition of Premises Wiring (System) tells us that the current in a switch is not in the Premises Wiring (System), and, therefore, an outlet occurs at the point on a switch where the switch wiring becomes internal to the switch.
Definition of Outlet.
The earliest definition of outlet, that I have in NEC books in my possession, is:
1933 NEC. Part 1. Chapter 1. Definitions.
Outlet. A point on the wiring system at which current is taken to supply fixtures, lamps, heaters, motors, and current-consuming equipment generally.
To this day, the core phrase is unaltered. The core phrase is "A point on the wiring system at which current is taken to supply. . ." Current. Not power, or energy, or voltage. This current is specifically current taken to supply utilization equipment. The electrical properties of the utilization equipment along with the voltage impressed on the utilization equipment determines the current that flows from the "outlet" to the utilization equipment.
</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The "outlet" does not utilize electrical energy. Current flows, or does not flow, in the outlet dependant upon the utilization equipment drawing the current.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The "outlet", itself, is a spot, a point, along the current path at which the current of the utilization equipment passes. Current passes from one side of this spot on the current path to the other side of the spot.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The definition of outlet doesn't concern itself with whether the same amount of current, or any amount of current, returns from the utilization equipment at, or near, the spot on the current path that the current was taken.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The definition of outlet doesn't specify the physical location of the utilization equipment relative to the location of the point on the wiring system at which current is taken.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The definition of outlet doesn't prohibit two or more outlets being in series with each other along the current path.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The definition of outlet doesn't prohibit the current taken to supply utilization equipment from re-entering the wiring system and from being taken again at another point on the wiring system.</font>
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The Problem.
The definition of outlet is a simple and uncomplicated definition, born in the early 1900s. The definition of outlet applies to AC and DC systems, single circuits, multiwire circuits, single phase AC and multiphase AC.
Over many decades, electricians have come to believe that "outlets utilize energy" and that "switches control energy, they don't utilize energy, so switches are not outlets". These two beliefs have risen to the level of intuitively self evident truth, in spite of the definition of Outlet clearly stating that an outlet itself is only current passing a point, that utilizing energy is not what the outlet itself does. Until the advent of the 2002 & 2005 NEC Arc Fault Circuit Interrupter requirements, the inaccuracy of these two beliefs had only academic interest. Today, these two inaccurate beliefs are adversely affecting new wiring installations.
Definition of Premises Wiring (System).
2005 NEC Article 100 Definitions.
Premises Wiring (System). That interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all their associated hardware, fittings, and wiring devices, both permanently and temporarily installed, that extends from the service point or source of power, such as a battery, a solar photovoltaic system, or a generator, transformer, or converter windings, to the outlet(s). Such wiring does not include wiring internal to appliances, luminaires (fixtures), motors, controllers, motor control centers, and similar equipment.
The Definition of Premises Wiring (System) was added to the NEC in 1978. The definition is in two parts.
The core of the first part is: "Premises Wiring (System). Wiring extends from point or source to outlet."
The core of the second part is: "Premises Wiring (System). Wiring does not include wiring."
The first part of the definition of Premises Wiring (System) begins "That interior and exterior
wiring,. . ." The one word
wiring is the subject of the first part of the definition.
"Premises Wiring (System)" (is) "That interior and exterior wiring,"
The Venn diagram, above, I understand from the language of Premises Wiring (System) is very simple.
The single red rectangle bounds everything that is Premises Wiring (System).
The single red rectangle is divided horizontally into two smaller red bordered rectangles: "Interior Wiring" and "Exterior Wiring".
The color added divides the contents of the same large rectangle (the Premises Wiring (System) into two parts. The orange is as labeled in the separate orange swatch, and the blue is as labeled in its separate color swatch.
When the second sentence of "Premises Wiring (System)" is applied, one puts a small circle, or whatever shape, representing an item whose internal wiring is not part of the wiring system, into the appropriate relationship to the four overlapping areas.
"Wiring" in context.
The context for the word wiring can be read to mean "The wiring an electrician installs for a customer." The context of "wiring" is broad and, in addition to the metal of the wire, includes all the parts that make the wiring a complete system from the source or supply to the outlet. These parts include , and are not limited to, insulation, sheath or raceway, connectors, enclosures, mounting and/or support systems, devices, fittings, etc.
The definition of Premises Wiring (System) continues, after "That interior and exterior wiring," with one unbroken phrase comprised of two clauses: "including power, lighting, control, and signal circuit wiring together with all their associated hardware, fittings, and wiring devices,". This unbroken phrase is making clear that the metal of the wire is not all that is meant by "wiring" even when considering power wiring, lighting wiring, control wiring and signal circuit wiring. This unbroken phrase says, among other things, that "wiring devices" are a part of "interior and exterior wiring".
"Wiring" appears in the NEC over 750 times in varied contexts.
The dictionary defines "wiring" as "a system of connected wires."
The dictionary defines "wire" as "a pliable thread or slender rod of metal." Note the lack of "conductive" in the dictionary definition. Any electrician can think of wire that is not pliable, nor a thread, nor slender, nor a rod. Certainly, the meaning of "wiring", as used in the definition of Premises Wiring (System) must include electrical conductivity and a more varied physical form, so, another definition than that of the common dictionary must be referenced.
My copy of the IEEE Standard Dictionary of Electrical and Electronic Terms does not include "wiring".
My copy of the IEEE Standard Dictionary of Electrical and Electronic Terms does include "wire" and it makes an interesting statement:
If a wire is covered with insulation, it is properly called an insulated wire: while primarily the term wire refers to the metal, nevertheless when the context shows that the wire is insulated, the term wire will be understood to include the insulation.
Looking at the context of "Interior and exterior wiring," in the definition of Premises Wiring (System), I find "wiring" to be the completed assembly I, as an electrician, leave at an occupancy at the end of my job. If my job was to do a temporary or permanent install, the completed assembly is the "wiring".
The point of this summary is to show that a wiring device, as used in the definition of Premises Wiring (System), is part of "That interior and exterior wiring,". The second part of the definition of Premises Wiring (System) invokes the subject of the first part ("Interior and exterior wiring") and lists wiring that is not included. The internal wiring in controllers are called out as not part of "such wiring".
Snap Switch as Controller
The common snap switch, as referenced by 2005 NEC 404.14, is used as a controller. Because a current traveling inside the snap switch is not traveling in part of the Premises Wiring (System), the current has to be taken from the Premises Wiring (System). Because the snap switch only carries and controls the current, the current is determined by the utilization equipment. The current in the snap switch is the current taken by the utilization equipment, it is the current supplying the utilization equipment.
The current taken from the Premises Wiring (System) at the point that the current goes internal to the controller is the current taken by the utilization equipment for its supply in utilizing electric energy.
Conclusion
Hence, an outlet occurs at a switch used as controller of an outlet.
A switch located in a bedroom and controlling an outlet outside the bedroom must be provided AFCI protection.
This is a general statement that only has application in wiring installations governed by the 2002 and 2005 NEC 210.12.
But a greater good is served by clarifying what an outlet, as defined, actually is. Electricians should not be misled into believing that a box is an outlet, that an outlet utilizes energy, that a switch cannot have an outlet inside it because a switch only controls energy. While most electricians believe these statements to be self evident truth, that doesn't make the statements correct.
Today, new installations of a switch inside a bedroom, controlling outlet(s) outside the bedroom, may be supplied by a non-AFCI protected overcurrent protective device. In most jurisdictions, the Authority Having Jurisdiction will approve the installation. All such non-AFCI installations will then operate, and, over the passage of time, will suffer a statistically guaranteed minimum number of failures. Some of these failures will result in property loss, injury and potentially death. Subsequent liability litigation can easily demonstrate how poorly electricians understand the meaning of outlet, and can easily demonstrate an outlet occurs in the switch inside the bedroom, as I have, and that the AFCI, had it been installed, would have prevented the loss.
It only takes one cup of coffee in one lap to result in litigation that changes what had been industry wide accepted practice.
It is time to pay attention to the confusion about what an outlet is, and teach a consistent perspective, based on the actual language of the NEC. The existing confusion is affecting installations of wiring systems adversely.