The NEMA 1-15P is the classic two-blade plug — no grounding pin — rated 15 amperes at 125 volts. It is the plug on countless lamps, clocks, phone chargers and other double-insulated appliances that do not require an equipment ground. It mates with the 1-15R receptacle and also fits the grounded 5-15R outlet, which is backward-compatible with two-blade plugs.
Why No Ground?
Grounding protects users if a fault energizes an exposed metal part. Devices with Class II / double-insulated construction enclose their live parts in two independent layers of insulation, so an equipment ground is unnecessary. Removing the ground pin makes the cordset lighter and cheaper — appropriate for low-risk, low-power products.
Polarized vs. Non-Polarized
The original 1-15P had two identical blades and could be inserted either way. The modern polarized 1-15P has one blade wider than the other so it only mates in a single orientation, ensuring the device's neutral conductor stays neutral. Polarization matters for products where the switch or fuse must sit on the hot line — most notably lamps, where the shell of the socket should remain on neutral. Non-polarized versions still exist for fully isolated, symmetric loads.
Construction and Applications
Nearly all 1-15P plugs today are over-molded onto flat parallel SPT (“zip”) cord or light SVT cord. Common applications include:
- Table and floor lamps
- Clocks, radios and small consumer electronics
- Low-wattage chargers and power supplies
- Seasonal and decorative lighting
Standards
Like all North American attachment plugs, the 1-15P is dimensioned by NEMA and safety-listed to UL 498. Cordset makers pay particular attention to the strain relief on light two-conductor cords, which are more prone to flex fatigue than heavier grounded cords. Although the connector is rated to 15 amperes, the finished cord's real limit is set by its wire gauge and length, so a light lamp cord should never be pressed into service as a high-draw extension. For guidance on residential plug and cord safety, the Electrical Safety Foundation International is a useful consumer reference.