Switches, Receptacles, and Panelboards – Based on the 2011 NEC
By Mike Holt for EC&M
Article 404 of the NEC applies to switches of all types, although the NEC doesn’t include a specific definition for a switch. However, six types of switches are defined in Article 100, which gives us a pattern to follow.
A dictionary definition of a switch is a device that opens or closes a circuit, or changes the connections from one circuit to another. In this regard, a circuit breaker is a special kind of switch, and is included in the Scope of Article 404 [404.1].
Neutrals
When wiring lighting circuits supplied by a grounded general purpose branch circuit, the 2011 NEC now requires you to provide a neutral conductor at nearly every switch point [404.2(C)].
The purpose of installing a neutral conductor at switching points is to complete a circuit path for electronic lighting control devices, such as occupancy sensors. For many such devices, you must provide standby voltage and current at the switch. When neutral conductors are not installed at switches, the unfortunate result is the equipment grounding conductor (EGC) may be be used to fulfill the function of the neutral conductor.While the current from an electronic lighting device on the EGC is typically less than 0.50 mA, the installation of many electronic control devices at switch locations in a building can result in an accumulation of excess current on the EGCs. With this Code change, gone are the days of using dead end 3-way switches and two-conductor switch loops.
You can omit the grounded conductor if:
- Using a raceway that is sized to accommodate an added neutral. The use of a raceway obviously allows the installer to pull in a neutral conductor should the need arise in the future, provided the raceway is large enough [404.2(C) Ex 1].
- For cable wiring methods, if an additional cable can be fished into the switch location in the future without removing finish materials such as drywall. This would require access through a framing cavity that is open at the top or bottom or through a wall, floor, or ceiling that is unfinished on one side [404.2(C) Ex 2].
Grounding switch plates
The metal mounting yokes for switches, dimmers, and similar control switches must be connected to an equipment grounding conductor of a type recognized in 250.118, whether or not a metal faceplate is installed [404.9(B)].
A few years ago, a listed switch constructed entirely of plastic entered the market. These switches don’t allow a metallic faceplate to be installed on them. Because a plastic (nonconductive) component is inherently safer than a metal component connected to an EGC, a new exception allows for this product [404.9(B) Ex 2].
Another exception addresses the use of wiring devices with integral enclosures. Similar to the switches discussed above, these have nonmetallic faceplates and don’t allow for the attachment of metallic ones [404.9(B) Ex 3].
Receptacle replacements
Receptacle requirements are in Article 406 (see Sidebar). New requirements have been added for the replacement of receptacles to address replacements in areas requiring AFCI protection, tamper-resistant receptacles, or weather-resistant receptacles [406.4(D)].
As aging wiring systems become of increasing concern in the electrical industry, the Code is taking a proactive approach to providing protection of these systems. Many areas of a dwelling now require the use of AFCI protection to help avoid electrical fires.
When AFCIs were first introduced into the NEC, the substantiation for their inclusion was based largely on electrical fires in older homes. However, the Code began by protecting new and future wiring systems, but didn’t address the older ones that contained many of the fires discussed in the AFCI arguments.
The 2011 NEC expands the AFCI requirements to older homes. Because older homes often don’t contain an EGC, installation of an AFCI circuit breaker does little in the way of protecting the branch circuits. The receptacle type AFCIs also provide a significantly lower level of protection, but they will be required nonetheless.
The 2008 NEC introduced the concept of tamper-resistant receptacles in dwelling units. The requirements of that section (406.11, now 406.12) apply to new installations. The 2011 Code now also requires that on existing dwelling units, any receptacles that are replaced will be replaced with tamper-resistant receptacles.
A similar change was made for weather-resistant receptacles, using the same logic as for tamper-resistant receptacles.
Wet locations
For receptacles in wet locations, the 2011 Code includes a new requirement for “extra-duty outlet box hoods” [406.9(B)(1)]. All 15A and 20A receptacles installed in a wet location must be within an enclosure that’s weather-proof when an attachment plug is inserted. For other than one- or two-family dwellings, the outlet box hood must be listed for “extra-duty” use if supported from grade.
All nonlocking type 15A and 20A, 125V and 250V receptacles in a wet location must be listed as weather resistant.
Exposed plastic surface material of weather-resistant receptacles must have UV resistance to ensure that deterioration from sunlight is minimal or prevented. In testing, receptacles are subjected to temperature cycling from very cold to very warm conditions, and then subjected to additional dielectric testing. The rapid transition from the cold to warm temperatures will change the relative humidity and moisture content on the device, and the dielectric test ensures that this won’t create a breakdown of the insulation properties.
Exception: Receptacles rated 15A and 20A that are subjected to routine high-pressure washing spray may have an enclosure that’s weatherproof when the attachment plug is removed.
Tamper-Resistant Receptacles in Dwelling Units
Receptacles installed above 5½ ft obviously don’t pose the same risk to small children as those receptacles below that elevation. Likewise, receptacles that are rendered inaccessible by equipment, and those that are part of luminaires, don’t pose the same risk. The 2011 Code recognizes these facts and includes relevant exceptions for them [406.12 Ex].
This exception also makes an allowance for replacements of nongrounding receptacles, since there are currently no tamper-resistant receptacles that are nongrounding.
The 2011 Code changes include the term “nonlocking” to describe the types of receptacles to which this rule applies. Only those receptacles that are of the straight blade configuration must comply with the tamper-resistant requirements of 210.52 and 406.12.
Guest rooms and guest suites often have children staying in them, so tamper-resistant receptacles have been added as a requirement for these locations also [406.13]. Guest suites that provide complete facilities for living, sleeping, cooking, and sanitation are considered dwelling units by the NEC, and as such were already required to provide tamper-resistant receptacles. It’s not just these, anymore. The 2011 NEC explicitly requires tamper-resistant receptacles in all guest rooms and guest suites.
Many children spend a great deal of time in child care facilities, yet the 2008 NEC required tamper-resistant receptacles only in dwelling units. Proponents of these devices immediately began hoping for expansion of these receptacles to other areas that have children as occupants. The 2011 Code now requires areas such as schools and day care facilities to use these receptacles [406.14]. Other areas where the rules aren’t quite as clear, however, include hospitals and other medical centers.
But what exactly is a “child care”facility? A new definition in Article 406 defines it as a structure used for educational, supervision, or personal care services for more than four children seven years in age or less [406.2].
Marking panelboards
The 2008 Code added a requirement to 408.3(F)(1) that panelboards installed in high-leg systems be marked accordingly. While a high-leg system does present some challenges for electricians, particularly those who have never worked on one, the challenges encountered working on an ungrounded system are even greater.
Due to the unusual characteristics of an ungrounded system, panelboards must now be marked to warn qualified persons that the panelboard they’re about to work on is installed as part of an ungrounded system [408.3(F)(2)].
Another issue arises in large commercial and industrial facilities, which may have dozens of panelboards in a single building. In such buildings, it’s often difficult to determine from where a given panelboard receives its electrical supply. Unfortunately, this may result in electricians working on energized panelboards, simply because they can’t locate the disconnecting means needed to de-energize the equipment.
The 2011 NEC now requires that all panelboards (other than one- and two-family dwellings) be marked to indicate where their source of supply is [408.4(A)]. This change should greatly reduce the risk encountered on service calls and maintenance work.
We have reviewed some of the significant changes in these three articles, but they each contain a great deal more information that did not change in 2011, so be sure to review the articles themselves as you prepare to install switches, receptacles, or panelboards.
Sidebar: Article 406
Article 406 covers the rating, type, and installation of receptacles, cord connectors, and attachment plugs (cord caps). It also addresses their grounding requirements. Some key points:
- Follow the grounding requirements of the specific type of device you’re using.
- When installing replacement receptacles, follow the requirements of 406.4(D).
- Mount receptacles following the requirements of 406.5.
Taken from Mike Holt’s 2011 Understanding the NEC Volume 1 Textbook. To order your copy, please click here, or call 888-632-2633
