Can someone tell me which rule dictates that only one grounded or ungrounded conductor can be secured under a terminal fastener? I can see it being a workmanship issue, but I've yet to find a ruling against it. I often find breakers, fuses and lugs with more than one wire connected.
Under B.C.Amendments (www.safetyauthority.ca/files/Amendments%20to%20Electrical%20Code.pdf) 12-116 reads as follows: (Italic are added subrules from the amendments) 12-116 Termination of conductors (see Appendix B) (1) Connection of conductors to terminal parts shall be made by means of pressure connectors, solder lugs or splices to flexible leads.
(2) The portion of stranded conductors to be held by wire-binding terminals or solderless wire connectors shall have the strands confined so that there will be no stray strands to cause short-circuits or grounds. (3) Stranded and solid conductors No. 10 AWG and smaller shall be permitted to be connected by means of wire-binding screws, or studs and nuts that have upturned lugs or equivalent.
(4) Stranded and solid conductors larger than No. 10 AWG shall be terminated in solderless wire connectors or shall be permitted to be soldered into wire connectors specifically approved for the purpose except where prohibited by Section 10.
(5) Terminals for more than one current-carrying conductor shall be specifically approved for the purpose and be so marked.
These are B.C. Amendments I don't know about Ontario.
This is not a CEC Part 1 issue, it is a CEC Part II issue instead. The individual devices used to terminate connections, switched, receptacles, circuit breakers, etc. will be certified to a Part II standard.
If the device is certified to have two wires under one screw, as in some duplex receptacles and some circuit breakers, then it is acceptable to have more then one wire under a terminal fastener. If the device is not approved for multiple conductors under a single connection point, then it is not permitted.
In panel boards the bonding terminals are approved for 2 #14 or 2 #12 Cu and 2 #12 and 2 #10 aluminum wires. This information is on the piece of paper that came with the panel you throw away without reading. Neutrals are approved for only 1 conductor. 4-026 also requires that you should be able to disconnect only 1 grounded circuit conductor (neutral) without disconnecting the neutral from any other circuit. A terminal with 2 neutrals if loosened to remove 1 wire would possibly open the other.
Mike, I'm aware of what you're saying and I agree with your comment.
Rick, I wondered why you wrote with such confidence. After checking your profile and finding out that you are an inspector, I then realized why. I accept the information that you've shared but it's unfortunate that we have to assume it. I would of liked to have seen my answer more clearly/specificaly addressed in the code. There are too many others out there who are taking it for granted that it is acceptable to stick as many wires under a breaker or fuse terminal and it would be nice to just be able to state a specific code ruling clearly stating why it is unacceptable to do so. Thanks for the clarification.