Question: Receptacles with more than one set of terminal
It is common to see three runs of 14/2 NM cable run into a receptacle box with two conductors on the side terminals and the third tapped into a back terminal. This is used to avoid a larger box size because of the splice. Are receptacles that are provided with more than one set of terminals Listed for tapping off more than one circuit, utilizing both the side and back wiring terminals?
Answer
The short answer is yes for receptacles Listed for the U.S. market and no to receptacles Listed for the Canadian market. This is due to the difference in certification requirements between the two countries. Receptacles evaluated to UL 498, The Standard for Receptacles for Plugs and Attachment Plugs requires receptacles to be tested using the side terminal and rear terminals on the receptacles concurrently, where the Canadian Standard, CSA C22.2 No. 42-M1984, General Use Receptacles, Attachment Plugs and Similar Devices does not address testing for this application. Receptacles for the U.S. market are Listed under the product category Receptacles for Plugs and Attachment Plugs (RTRT) located on page 295 in the 2008 UL White Book.
The Guide Information for (RTRT) states single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have been investigated to feed branch-circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:
- Back wire (screw actuated clamp type) terminations Receptacles and Stranded Conductors with multiple wire access holes used concurrently to terminate more than one conductor
- Side wire (binding screw) terminals used concurrently with their respective push-in (screwless) terminations to terminate more than one conductor.
Single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have not been investigated to feed branch-circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:
- Side wire (binding screw) terminal with its associated back wire (screw actuated clamp type) terminal
- Multiple conductors under a single binding screw
- Multiple conductors in a single back wire hole
Receptacles for the Canadian market are Listed under the product category Receptacles for Plugs and Attachment Plugs Certified for Canada (RTRT7) located on page 434 in the 2008 Canadian White Book. The Guide Information for (RTRT7) addresses this issue as follows: Single and duplex receptacles rated 15 amp and 20 amp that are provided with more than one set of terminals for the connection of line and neutral conductors may be used to feed a single set of branch-circuit conductors connected to other receptacles on a multi-outlet branch circuit. These devices have not been tested for tapping off more than one circuit from the receptacle by utilizing both the side-wiring and back-wiring terminals on an outlet. The Guide Information for the product categories discussed above can also be accessed on UL’s Online Certification Directory atwww.ul.com/databaseand by entering the four or five digit category code in the Category Code search field.
The special UL meeting for government inspections provide us an excellent opportunity to ask questions of UL engineers and to clarify UL requirements. The “UL Question Corner” answers questions of general interest that are sent in from authorized government inspectors and we believe will have interest for many inspectors.
