15 amp receptacles are allowed on 20 amp circuits as long as there is more than one receptacle.

A single duplex receptacle is allowed.

The feed throuhg on the side of the 15 A receptacle is sized for 20 amps.

If there is more than one outlet (and even a regular duplex counts as two) then 15 amp receptacles are fine.

They can be 15a as long as there is more than one receptacle. A single receptacle will not fly but one or more duplex receptacles is fine. 2008 NEC 210.21(B)(1)

This post was edited by btharmy on Wed, Jan 2, 13 at 14:19

Don't forget, they need to be GFCI protected.

If the garage is at or below grade level...

ronnatalie said "If the garage is at or below grade level..."

Receptacles in garages are required to have GFCI protection. 210.8(A)(2)

The requirement is for Garages, and also accessory buildings that are below grade (in addition to garages). Not garages and accessory buildings that are below grade. The key is the comma and the word "also". It changes the context of the sentence. Anything after the comma is in addition to the rule for garages, which is to have GFCI protection for all 120v receptacles.

And to be sure that it is not considered a Hazardous Class, keep all premises wiring electrical devices at least 18" above the floor.

btharmy is correct, I somehow had that misinterpretted in my memory. It should also be remembered that in the 2008 requirements the "not readily accessible" and garage door opener exceptions were removed.