A.Steve Campolo, vice president for engineering at Leviton, responds: UL specifically tests receptacles for the ability to safely carry downstream current. This testing is usually conducted at 20 amps, since a 15-amp receptacle can be wired on a 20-amp circuit and thus carry the 20-amp feed-through current. As long as the receptacle is rated and UL-listed for feed-through wiring, as well as properly installed, it should be safe as intended by UL’s Standard for Safety (UL 498), which covers receptacles.
The pigtail method transfers the connection point from the receptacle to a wire nut. So instead of the feed-through current going through the receptacle, it goes through the wire nut. Which junction is better? It’s hard to say; it depends on the skill of the installer. The methods should work equally well as long as the installation is properly...
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