Two Conductors to Single Outlet Terminal

[E40]

Hello All,
My startup company recently designed a new electrical outlet. Through our design iterations we've tried a few different attachment methods for the conductors on the back housing. We've settled on a similar design to what you'd see on a main breaker panel bar (like this one). Though each terminal would be separate. There's a tubular opening that you can stick the conductors into, then a screw that goes through the side of the tube to apply pressure to the conductor.

My question is around the NEC requirements for the number of conductors that can be installed into this terminal. Seeing section 110.14 a) I'm inclined to think that we could accommodate 2 conductors if we label the terminals as being able to handle such. However, I've received feedback from an electrician that the NEC does not allow two conductors to terminate at a single screw. I know that we could use pigtails but I'd like to get this topic clarified as well so I'm confident in our guidance to consumers.

I'm looking for guidance relative to the correct NEC sections to help make sure we're designing our product correctly. Any feedback is appreciated.

Regards
E40

 

[don_resqcapt19]

The code clearly permits more than one conductor in a termination where the termination is "identified" for that use. Many AHJs read "identified" to be the same as "listed".

 

[jap]

If this will be a terminal block for anything other that Equipment Grounding Conductors I think I'd choose a different type of terminal block.


JAP>

 

[Carultch]

Hello All,
My startup company recently designed a new electrical outlet. Through our design iterations we've tried a few different attachment methods for the conductors on the back housing. We've settled on a similar design to what you'd see on a main breaker panel bar (like this one). Though each terminal would be separate. There's a tubular opening that you can stick the conductors into, then a screw that goes through the side of the tube to apply pressure to the conductor.

My question is around the NEC requirements for the number of conductors that can be installed into this terminal. Seeing section 110.14 a) I'm inclined to think that we could accommodate 2 conductors if we label the terminals as being able to handle such. However, I've received feedback from an electrician that the NEC does not allow two conductors to terminate at a single screw. I know that we could use pigtails but I'd like to get this topic clarified as well so I'm confident in our guidance to consumers.

I'm looking for guidance relative to the correct NEC sections to help make sure we're designing our product correctly. Any feedback is appreciated.

Regards
E40

The NEC only allows it, if the factory specifications of the termination device indicate that it can fit and has been tested for multiple wires per terminal, of the size(s) you intend to use.

If unspecified, it is only permitted to accommodate 1 wire per terminal.


From Square D, that particular kind of terminal block specifies the following:
(1) #14 - #4 copper wire
(1) #12 - #4 aluminum wire
(2) #14 - #12 copper wires
or (2) #12 - #10 aluminum wires.

 

[JFletcher]

Hello All,
My startup company recently designed a new electrical outlet. Through our design iterations we've tried a few different attachment methods for the conductors on the back housing. We've settled on a similar design to what you'd see on a main breaker panel bar (like this one). Though each terminal would be separate. There's a tubular opening that you can stick the conductors into, then a screw that goes through the side of the tube to apply pressure to the conductor.

My question is around the NEC requirements for the number of conductors that can be installed into this terminal. Seeing section 110.14 a) I'm inclined to think that we could accommodate 2 conductors if we label the terminals as being able to handle such. However, I've received feedback from an electrician that the NEC does not allow two conductors to terminate at a single screw. I know that we could use pigtails but I'd like to get this topic clarified as well so I'm confident in our guidance to consumers.

I'm looking for guidance relative to the correct NEC sections to help make sure we're designing our product correctly. Any feedback is appreciated.

Regards
E40

The NEC is not a design manual. I personally think you'd be better off talking to electricians to see what they want. I'd like to see a low-cost 15a duplex receptacle that utilizes pressure plates (like a gfci has) and lacks backstab ports. Maybe even a groove built into the yoke that strips 12 and 14 ga wire. Would certainly save time over looping wire over screws and be rock solid. GFCI pressure plates are rated for two wires....

 

[E40]

Thank you for each of the responses! I'd love your input on our design to see what concerns you may have. However, I don't want to post our URL on the forum in case that violates the rules. If you'd be open to looking at our site/product please send me a PM and I'd be happy to provide the address.

Regards,
E40