I’m ready to put the covers back on my breaker boxes & I’m wondering if there are typically any codes as to how it should be done. I have a flush mount box in a finished garage, so it wouldn’t be easy to come out the side. It would be easy to just notch the drywall under the edge of the cover and bring the wires out in a zip tied bundle. Is there any reason why not?
I have the exact same situation, but am not an electrician and cannot say for certain. However, I think it is always good practice have current sensor wires emerge through knockouts fitted with UL approved plastic strain reliefs such as Arlington LPCG50-10 1/2-Inch Strain Relief Electrical Cord Connector, which is available on Amazon.com. If the breaker panel was in the open, you could just use these to bring wires directly through knockouts in the panel to an IotaWatt mounted on the wall (which would not require an enclosure).
If the panel is mounted in a wall, it get’s trickier. The best option would be to have an electrician mount an NEMA enclosure above or below the panel, connected to it by a short conduit or a double-ended metal fitting. The strain reliefs could then be mounted on the enclosure, or if the enclosure is plastic, the IotaWatt could even be placed inside if it still gets a good WiFi signal. (In that case, the IotaWatt power supply and reference transformer wires would enter the enclosure through strain reliefs.)
I am not very comfortable with the idea of notching the drywall to bring out the wires, even if you fill the notch with drywall compound. I would definitely check with an electrician, building inspector, or other expert before doing that.