InspectAPedia ® | ||||||||||||||||||||||||||
| Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice |
| |||||||||||||||||||||||||
| InspectAPedia Home |
| | Air Conditioning |
| | Electrical | | | Indoor Environment |
| | Exteriors | | | Heating | | | Home Inspection |
| | Insulate Ventilate |
| | Interiors | | | Mold Inspect/Test |
| | Plumbing Water Septic |
| | Roofing | | | Structure | | | Contact Us |
| Directory of Professionals to Inspect or Test a Building | ||||||||||||||||||||||||||
Mobile View ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR AFCIs ARC FAULT CIRCUIT INTERRUPTERS ALUMINUM SECs & WIRING ALUMINUM WIRING HAZARDS AMPS & VOLTS DETERMINATION AMPACITY - the LIMITING FACTOR BOOKSTORE - ELECTRICAL CIRCUIT BREAKER FAILURE Classified CIRCUIT BREAKER WARNING DEFINITIONS of ELECTRICAL TERMS DIRECTORY OF ELECTRICIANS ELECTRIC METERS & METER BASES ELECTRIC PANEL AMPACITY ELECTRIC PANEL INSPECTION ELECTRICAL BASICS Electricity Basics - how it works Electrical Circuit ID, Map & Label Electrical Circuits, shorts Electrical Code Basics Electrical Conduit Tips Electrical Grounding Basics Grounding Knob-and-tube wiring Electrical Shorts Polarized Plugs, Receptacles, Lights Electrical Outlet-how to add Electrical Splices, how to make Electrical Tools & Tests Electrical Wire Stripping Tips Electrical Wiring Books & Guides Electrical Wiring in Old Houses ENERGY SAVINGS in BUILDINGS FEDERAL PACIFIC FPE HAZARDS GROUND SYSTEM INSPECTION Why Grounding is Needed Gas Piping Ground Bond Table of Ground Wire Sizes False Ground at Receptacles False Neutral Connections Case History: Double Fault Leads to Loss of Power Case History:Loss of Neutral Shocks Homeowner Electrical Service Grounding Checklist FEDERAL PACIFIC FPE HAZARDS GROUND SYSTEM INSPECTION KNOB & TUBE WIRING LIGHTNING PROTECTION LOW VOLTAGE BUILDING WIRING MAIN DISCONNECT AMPACITY MULTI-WIRE CIRCUITS PUSHMATIC - BULLDOG PANELS RUST in ELECTRICAL PANELS SAFETY FOR ELECTRICAL INSPECTORS SE CABLE SIZES vs AMPS SQUARE-D RECALLS UNDERGROUND SERVICE LATERALS VOLTAGE MEASUREMENT EQUIPMENT WIND TURBINES ZINSCO / SYLVANIA HAZARDS
|
This article answers basic questions about electrical grounding safety in older homes. Readers of this article should also be sure to see our main article on electrical grounding at GROUND SYSTEM INSPECTION. There we discuss the more broad topic of electrical grounding. Also review Safety Hazards and Safe Electrical Inspection Procedures for Inspectors examining Residential Electrical Systems and Local Electrical Grounding for safety procedures during inspection of the grounding system. Readers of this article should also see ELECTRICAL DEFINITIONS. This website provides information about a variety of electrical hazards in buildings, with articles focused on the inspection, detection, and reporting of electrical hazards and on proper electrical repair methods for unsafe electrical conditions. Critique and content suggestions are invited. Credit is given to content editors and contributors. Elizabeth Sluder contributed to the original text of this article. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. Sketch at page top courtesy of Carson Dunlop. Electrical Grounding & Other Electrical Safety Concerns in Older HomesOlder homes often have electrical receptacles and fixtures that are ungrounded, and many local codes do not require that they be rewired so they're grounded. Still, grounding is worth adding to your system because it adds protection against electrical shock. Grounding provides a third path for electricity to travel along, so if there is a leak of any sort, it will flow into the earth rather than into the body of a person who touches a defective fixture, appliance, or tool. An electrical system is grounded with a grounding rod driven at least 8 feet into the ground outside the house or by connecting to a cold water pipe. Each individual branch circuit must be grounded as well, either with a separate wire that leads to the neutral bar of the service panel or with metal sheathing that runs without a break from each outlet to the panel. (In theory, electrical outlets can be grounded individually, but this is impractical.) Absence of good electrical grounding at older homes
Ungrounded, and False-Grounded electrical circuits in older homesTwo Slot Electrical Receptacles with No GroundIf your outlets have two slots that are the same size, then they are neither polarized nor grounded. These are non-polarized or un-polarized, un-grounded electrical receptacles. This leaves you with no protection against shocks from defective fixtures or appliances using that outlet. At the very least, you need to install polarized outlets. You cannot and should not install grounded electrical outlets on circuits where no ground path is actually present (such as knob and tube wiring). To provide a grounded outlet where no ground is present is dangerous. Some locations in your house- especially where the outlet and/or appliances may become wet- require ground-fault circuit-interrupter (GFCI) receptacles. Older, ungrounded circuits usually are protected by polarization, which is less effective than grounding but better than nothing. Grounded and polarized receptacles work only if they are wired correctly. An older home may have electrical service that is inadequate or even unsafe. It can be confusing, as well. If you are unsure about your home’s wiring, have a professional check it out. See False Ground at Receptacles and False Neutral Connections for examples of how wiring mistakes on un-grounded or even grounded electrical circuits can be dangerous. Other Electrical Ground Wiring Problems in Older HomesHere are a few things to consider when inspecting the electrical system in an older home. Warning: this list of electrical wiring defects and safety concerns in older homes is incomplete. Contact Us to suggest corrections, changes, or to add additional items. Knob-and-tube wiring in older homes
For an example of installing an additional electrical receptacle, see Electrical Outlet-how to add. Warnings about Polarized Electrical Plugs, Receptacles, and Lighting Fixtures
"Polarity" in an electrical receptacle and on the device that plugs into or connects to it means that we're making sure that we connect the "hot" or "live" side of the electrical circuit to the connection point in the appliance or device that was intended to be "hot" or "live". Carson Dunlop's sketches show why it's important to respect polarity when connecting an electrical receptacle, a lamp or any other appliance. Never clip or file down the prongs on a grounded or polarized plug in order to force it to fit into an older electrical receptacle. The risk is that your plug will be installed with reversed polarity - connecting the "hot" side of the electrical circuit to the normally neutral-wired side of the appliance. We've found appliances (a coffee maker) that simply burned up when connected in this fashion. Go to the heart of the problem: Test and upgrade your electrical circuit system. See ELECTRICAL GROUND SYSTEM INSPECTION for details about how to inspect the electrical grounding system at a building. Also, see details about electrical grounding at Electrical Circuits, shorts, and at Electrical Wiring in Old Houses and at Electricity Basics - how it works.
... Technical Reviewers & References
Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
|
|||||||
|
ELECTRICAL HAZARDS, INSPECTION, REPAIRS More Information InspectAPedia Blog - News Updates Air Conditioning & Heat Pumps Bookstore Electrical Environment Exteriors Heating Home Inspection Insulate Ventilate Interiors Mold Inspect/Test Plumbing Water Septic Roofing Structure Accuracy & Privacy Policies Contact Us |
More Information on Building Diagnostic Inspections and Repairs
|
04/11/2009 - 08/27/2008 - InspectAPedia.com/electric/Old_House_Wiring.htm - © 2009 - 2008 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark