The Technical Stuff
As of 2008, the National Electrical Code (NEC) is requiring installation of tamper-resistant receptacles for all dwelling units using 125 volt 15 and 20 ampere receptacles. (See NEC 406.11 and 210.52) This also includes remodels and upgrades to older electrical components in all single and multi-family homes.
What type of receptacle are they referring to?
The requirement includes duplex outlets, GFCI's, single receptacles, floor boxes, and any other specialty product with electrical outlet capability. Even dedicated receptacles, not readily accessible, must be tamper resistant.
So, what makes an outlet "TR"?
Simply, a spring loaded shutter mechanism will allow a plug to enter (double prong entry), but resists access to any single prong entry item like a key, knife, paper clip, nail, screw, or other foreign object that may be inserted into an outlet by a small child. Prior to this creation, outlets were often protected from small children by plastic plugs placed into the outlet. While providing a level of protection for children, they also provided frustration for many adults attempting to use.
How do I identify an outlet that is tamper resistant?
Look at the front of the outlet and you will see the letters "TR" stamped into the face. This may be seen as simply TR or you may see a manufacturers model number with TR incorporated into the number. Also, viewing the outlet directly will allow you to see a 'gate' or blockage at the outlet entry holes. Some outlets will be designated at Weather Tamper Resistant (WR) meaning for use out of doors.
A Good Idea
Incorporating TR type receptacles into new construction is setting a new standard in safety. While not necessary or required to change out all your outlets if your home was built prior to 2008, it would be a good idea to purchase TR products for any future replacement of expired outlets. Also, if remodeling, they will be required by permit.