Was at my fathers house and decided to pop of his deadfront to have a look at the wiring. I noticed the 20amp breaker for the bathroom/bedroom upstairs is wired with 14g wire and not 12g. I know it isn’t correct but how big of a safety issue is this? Is this enough to cause the conductor to overheat? No signs of overheating from what I can see.
Also I noticed a few double taps to breakers which are sylvania one of which was the doorbell transformer tapped off another circuit. Couldn’t determine brand of panel.
It is a code issue. Past that the issue would be based on the load imposed. Too high of a load and the safety factor built in is gone while the potential for overheating or a fire increases.
From a safety perspective you could change the 20 amp CB to a 15 amp to ensure the protection of the #14 conductors but in doing so you may find quite a bit of nuisance tripping if the circuit has other loads on it and you want to plug a hair dryer into the bathroom receptacle. That could be the reason someone installed the 20 in the first place.
The better part of this whole story us that an electrician was the former owner and there was a home inspection done with nothing reported about the panel. There are other issues besides the ones I outlined.
#14 is good for and will handle 20amps, however code requires that an extra safety factor be applied to 14,12, and 10 gauge wires limiting the OCPD to 15, 20 and 30amps respectively.
Motors and other specialty items do not follow this rule.