Splicing wires in an electrical circuit panel

[J Harvey]

I am in the process of installing a manual transfer switch into my Breaker panel to be used for a generator. I am being told that Massachusetts eletrical code does not allow wire splicing and wire nuts within the breaker panel. Is this true? How can I validate?

[Corn Walker]

MA has adopted the 2011 NEC with amendments (http://www.lawlib.state.ma.us/source/mass/cmr/cmrtext/527CMR12.pdf).

[J Harvey]

Corn - Thanks for the info. The only section I found somewhat related to my question was section 110.14 (A) in the Massachusetts Electrical Code Amend. document you sent.

Connection by means of wire binding screws or studs and nuts having upturned lugs or equivalent shall be permitted for 10 AWG or smaller solid conductors. Where stranded conductors are terminated on and not looped through such terminals, the terminals shall be identified for such use, or the strands at the terminals shall be made solid.

Additional question:

I will be splicing, using a wire nut to join stranded wire to solid in the main breaker panel, can I do this per the last sentence in the above code statement? Or is there anything else I may be missing here?

[Corn Walker]

Corn - Thanks for the info. The only section I found somewhat related to my question was section 110.14 (A) in the Massachusetts Electrical Code Amend. document you sent.

Connection by means of wire binding screws or studs and nuts having upturned lugs or equivalent shall be permitted for 10 AWG or smaller solid conductors. Where stranded conductors are terminated on and not looped through such terminals, the terminals shall be identified for such use, or the strands at the terminals shall be made solid.

Additional question:

I will be splicing, using a wire nut to join stranded wire to solid in the main breaker panel, can I do this per the last sentence in the above code statement? Or is there anything else I may be missing here?


That amendment refers to terminal lugs, not to splicing wires. It's referring to the style of terminal that is allowed.

The only prohibition I'm aware of is when the panel is not specifically listed for use with through-connections (i.e. use as a raceway or junction box), which is what you're proposing to do. I suspect this is what you're hearing, but that's not a Massachusetts-specific requirement.

Also, sometimes the path of least resistance is just to talk to the inspector of wires and see what they will or won't allow. The NEC specifically allows for a single luminary serving the bathroom to be fed from the required dedicated 20A circuit for receptacles. The AHJ wouldn't allow it, and it was easier to just feed from a nearby bedroom circuit than to argue about it (making the inspector cranky and adversarial in the process).

[J Harvey]

Thanks for the info and advice. As you suggested, best path is to talk to the inspector.