I have a 15 amp breaker that’s used for my foyer/family room. The builders double tapped that breaker to add a 16V-10VA transformer for the doorbell to the side of the service panel via a knockout. See pics below.
I plan to swap the existing transformer with a 16V-30VA transformer to power a Unifi G4 Doorbell along with my NuTone chime box. In the process, I’d like to correct the double tap.
My question is: Do I need to worry about the wire gauge of the transformer wires if I wanted to correct the double tap via a pigtail? The AWG of the transformer is 18. As far as I know, this is not up to for code for a 15 amp circuit. Is it ok if I proceed to pigtail with the mismatched wire gauges? I understand the current transformer is also a different gauge wire and double tapped which seems to work fine, but I’d like to correct it.
My other question is: Instead of a pigtail, if I were to add another single pole 15 amp breaker to correct the double tap, would I need to worry about the wire gauge of the transformer as long as the doorbell is the only thing on that breaker?
Finally, I know it’s “common practice” to double tap for doorbell transformers, so how bad is it really if I didn’t fix the double tap?
I’m not so concerned about being perfectly up to code. Instead, I’m looking for something that is safe and reliable.