What is a non-grounding type receptacle?
Non-grounding type receptacles are not a great hazard by themselves (if installed properly and used only to connect equipment that is not broken), but their presence is an indication of very old wiring inside the walls behind the receptacle, and the likelihood that the old wiring is shared by many locations originally designed to provide low power to mostly floor lamps (100W each vs. 300W and up for computers, vacuums, air conditioners, etc.).
By contrast, modern grounding-type receptacles typically connect to modern wiring that includes an equipment grounding conductor that bonds the receptacle and any cord-and-plug connected load to the building system ground (it is literally a single, chemically-bonded piece of metal running from the receptacle all the way to the dirt under your building). This creates a safe path for fault current in the event a ‘hot’ wire improperly contacts and energizes the accessible surfaces of the receptacle or connected loads. The fault path carries high current (100′s of Amps) sufficient to trip the 15A or 20A circuit breaker in fractions of a second. A non-grounding-type receptacle can only trip its circuit breaker if there is a direct short between the supply conductors (‘hot’ and neutral), if the connected load draws current greater than the breaker rating for several minutes, or if there is a short between ‘hot’ and neutral in the connected cord or cord-supplied equipment.
Receptacle grounding also minimizes physical damage and shock hazard arising from surge voltage induced on metal in the home by nearby (or direct) lighting strikes.
Newly-installed receptacles under the 2008 edition of the National Electric Code (NEC), enforced in Philadelphia since 2011, must be Tamper Resistant (TR) type, if located within 6′ above finished floor. An exception is made where non-grounding type receptacles must be installed because no ground facility exists in the underlying wiring method, because TR receptacles are required only if available, and there are no TR-type non-grounding receptacles.
Mechanical considerations also play a role in evaluating the relative safety of receptacles. All receptacles rely on spring tension in their sockets to maintain electrical contact with cord-and-plug connected appliances. As the receptacles age, springs may become fatigued and provide poor contact even with full insertion, and/or allow plugs to slip partially out, further impeding good electrical contact. Poor contact can result in arcing, which heats up the termination and may ignite accumulated dust/hair, or overheat the attached cords or the branch circuit wires connected to the receptacle device to the point of igniting the plastic insulation (this is one reason AFCI protection has been mandated for all newly-installed outlet locations in residences, that are not elsewhere required to be GFCI-protected).
Because of the circuits’ tendency to be overloaded due to the number of locations served, the age of the wires and the receptacle devices, and the lack of an equipment grounding conductor that provides added safety in the event of circuit faults, and the likelihood that the receptacles have fatigued spring sockets, high-power appliances including SPACE HEATERS, HAIR DRYERS and AIR CONDITIONERS SHOULD NEVER BE ATTACHED TO THESE RECEPTACLES.
Off-site Links ->
- Annapolis Home Inspection, LLC Aluminum branch circuits, homes 1965-1972
- ComplianceAndSafety.com OSHA Electrical Safety Training
- Electric Monk TV (YouTube) Video channel for PhillyLicensedElectrician.com Robert Monk
- EnergyConservation HowTo A tinkerer genius discusses energy conservation and his ladder system for accessing the attic (where a lot of energy-saving work happens).
- PennFuture Energy Center Energy and energy efficiency news for the Commonwealth of Pennsylvania
- Phila area rife with building efficiency upgrade opportunities Philadelphia Inquirer article discusses recent study showing Philadelphia’s inner-ring suburbs stand to save from energy conservation retrofits.
- Philadelphia Row-house Manual A design, maintenance, and modifications manual for our most widely-used form of housing.
- Robert Monk Robert Monk’s personal blog
- SolarCities (DOE) Solar PV Levelized Cost Interactive Comparator Simple graph compares ‘levelized cost’ of energy from solar PV to conventional grid rates, with a time-slider interactive feature.
- The Circuit Detective – Solve Home Electrical Problems Yourself! Electrical troubleshooting procedures pitched to homeowners.
- The Energy Co-op Blog from a leading alternative energy provider in PECO territory, includes fun conservation tips.
- Weatherization: the anti-Solyndra Salon.com article praising the continued success of the federal Weatherization Assistance Program (WAP), low-income energy-savings and job-creation.
- West Philly Tool Library Official site of WPTL, Philly’s own community tool lending library: like a book library, but tools!
- WestPhillyLocal .com Site name say sit all.
- Bartram's Gardens Founded in Philadelphia’s colonial era, today the gardens continue pioneering in horticulture and agriculture with a variety of herbs, trees and other vegetation in an arboretum/gardens on the Schulkill River banks, and a new farm abutting sadly neglected
- HiddenCity Philadelphia Surprising places it takes an adventurer to discover; events, too.
- Philly Household Hazardous Waste Drop-off Schedule City of Philadelphia dates and places for disposing of spent batteries, CFL lamps, unused paint and cleaning products, etc. LovePhilly: don’t pour these in the drain or send them out with the trash.
- Reading Terminal Market Purveyors of fine foods and foodie stuff, all under one roof downtown under the PA Convention Center
- Secret Garden on the Rails Jacques-Jean Tiziou shows some dramatic natural and urban and naturalized-urban scenes along abandoned rails of Philadelphia
- Sketch Burger, Fishtown A vegan-friendly burger joint with a #1 in Philly contender beef burger, best fries that somehow stay fresh for 1/2 hour while you tackle burger, and a vegan cafe vibe of friendly folks.
- WXPN: Philly sings in key of love Love songs by Philly artists