Outlets without grounding can be a safety issue. Electrical shocks can result when an outlet is not properly grounded. Newer home built under modern codes are required to have grounding for all electrical outlets.
Older homes may not have grounded receptacles. Using adapters is not a good practice, due to the fact that they still need to be grounded. You can ground to the box if it is hooked to metal conduit.
This is rare in residential homes. The ground wire is a safety feature the prevents electrical shock in the event of a neutral failure.
Homeowners that have outlets without grounding may want to consider upgrading their wiring. This is a big undertaking and beyond the scope of this article. You will need to hire an electrician. It is possible that you can get grounding installed on certain key outlets, such as those that need GFCI protection. Again you will need to consult an electrician or develop basic wiring skills of your own.
Testing an Outlet Ground
You can use an inexpensive circuit tester to check to see if an outlet is grounded. Another option is an outlet receptacle tester. These cost a bit more, but they test for multiple conditions.
A circuit tester lights up when there is power traveling between the two contact points. In a grounded outlet the small slot should be the power, the larger slot is the nuetral. Normally, when power is used, it travels from the hot, through the device and back through the neutral. If for some reason the neutral fails, the ground is used to convey the power back safely.
An outlet receptacle tester has three lights on it the will light up in different combinations, depending on how the outlet is wired. One of the things they test for is 'open ground' and 'open neutral'. Either of these situations is not desirable. For complete instructions on testing an outlet, see the article 'How To Test an Outlet'.
Fixing an Outlet Ground
When an outlet shows 'no ground' or 'open ground' it may just be a problem at the box. A loose wire or an incorrectly wired receptacle could be the problem. If that is the case, it is not too difficult to fix the wiring. It may just be a matter of switching the wires or connecting the outlet to the ground wire.
For instructions on wiring an outlet, see the article 'How To Wire a Receptacle'. This article shows the correct placement of wires to have the outlet work properly.
Adding a Ground Wire
A common problem in older houses is wiring that does not have a ground wire. As mentioned above, the ground wire is only used when there is a failure or some distruption in the current going back through the neutral. Years ago it was not considered necessary to have a ground wire. Ground wires were added as safety features and are now part of the electrical code.
Installing New Wiring