The NEMA 1-15R is the two-slot, ungrounded receptacle rated 15 amperes at 125 volts. It is the outlet counterpart to the 1-15P plug. Once the default household outlet, the 1-15R is now largely a legacy and cord-end configuration, having been superseded in fixed wiring by the grounded 5-15R.
Where It Still Appears
Although new residential construction requires grounded outlets, the 1-15R pattern lives on in several places:
- Cord-end connectors on light-duty extension cords and cube taps for two-blade appliances
- Built-in outlets on lamps, power strips and older equipment
- Legacy wiring in buildings that predate mandatory grounding
Polarization Without Grounding
A polarized 1-15R has one slot taller than the other so a polarized 1-15P mates in only one orientation. This preserves correct hot/neutral identity even though no ground is present — important for the same lamp-and-switch reasons described for the plug. It is worth emphasizing that polarization is not a substitute for grounding: it controls conductor identity, not fault current.
Identifying a Two-Slot Outlet
A 1-15R is easy to recognize: it has only two vertical slots and no rounded ground hole below them. On a polarized version the left slot (neutral) is noticeably taller than the right. If you find one in service, treat it as ungrounded even if a later three-prong outlet has been swapped in ahead of it — a grounded receptacle is only as good as the ground path behind it. Inexpensive plug-in testers can confirm whether a ground actually exists at the box.
Upgrading Legacy Outlets
Replacing an ungrounded 1-15R with a grounded 5-15R requires an actual equipment-grounding path back to the panel. Where none exists, the National Electrical Code permits specific alternatives, such as protecting the circuit with a GFCI device and labeling the outlet “GFCI Protected, No Equipment Ground.” That approach restores shock protection for people without pretending a ground exists for equipment that needs one. Dimensional standards for the 1-15R are maintained by NEMA and safety requirements by UL 498. When in doubt about an older installation, have the circuit evaluated by a qualified electrician before adding load.