Appleton™ U-Line™ Factory Sealed 20 Amp Plugs and Receptacles

U-Line™ Factory Sealed 20 Amp Plugs and Receptacles are used with stationary or portable electrically operated devices in hazardous locations. The ECP Interchanger plug is designed with built-in switch contacts which activate when the plug is twisted into the receptacle. This design allows the ECP plug to fit into standard NEMA 5-20R and 6-20R receptacles, but does not allow standard plugs to be used with the receptacle, ensuring that only safe connections can be made in a hazardous location.


  • Energized receptacle contacts deeply recessed to reduce danger of accidental touching
  • Unique blade-type, brass contacts exert constant pressure along entire contact surface and provide superior electrical contact.
  • Insulators provide superior dielectric and mechanical strength and lowest arc tracking
  • ECP plug fits any standard non-explosionproof receptacle (NEMA 5-20R, or 6-20R) as well as U-Line™ explosionproof receptacles
  • Choice of malleable iron receptacle and mounting box or aluminum receptacle and mounting box
  • Ground fault circuit interrupting cover and receptacle combinations available
  • U-Line™ EFSR-K receptacle covers are UL Classified when used with Killark™ SWB series mounting boxes
  • Intermateable with competitor’s plugs of like configurations


Hazardous Area Classification
Class I, Division 1 Groups B, C, D; Class I, Division 2 Groups B, C, D; Class II, Division 1 and 2 Groups F, G; Class III; NEMA 3, 3R
125 Vac or 250 Vac
Number of Poles
Number of Wires
Horsepower Ratings
1 or 2
Plug Cable Diameter
.538 – .639
Mounting Box Entries
Dead-End or Feed-Thru
Malleable Iron Material and Finish
U-Line™ M series mounting boxes and receptacle covers are malleable iron with a triple coat finish of (1) zinc electroplate (2) chromate and (3) epoxy powder coat
Aluminum Material and Finish
Standard receptacle covers and (optional aluminum mounting boxes) are copperfree (4/10 of 1% max.) aluminum with epoxy powder coat
Insulator Block Material
Glass-filled reinforced polyester
Glodok Exproof Product