Wire question for Maxxair fan install

[Motts461]

I have a question about a mixing wire sizes for a Maxxair fan installation. I have a 2019 Minnie Winnie 31G and I am installing Maxxair Deluxe fan in the bedroom. I have run 14 gauge over to the cabinet above the headboard of the bed. There is 14 gauge wire there feeding the overhead LED reading lights. I also found an unused plug next to the water tank under the bed that is for the tank heater that I do not have. This wire is 12 gauge and can be accessed under the bathroom sink. My question is would I be better off just tapping into the 14 gauge wire feeding the reading lights or tapping into the unused 12 gauge wire for the tank heater? My original plan was to use the LED light circuit 14 gauge to 14 gauge. When I found the unused circuit I thought this would be better but wasn't sure about mixing the 14 gauge wire with the 12 gauge wire. The Maxxair fan requires a 5 amp service and both circuits are fused with a 15 amp fuse. I may be over thinking this any help would be appreciated.

[ThomB]

I can’t say it’s the correct answer but I’d just use the available 12 gauge circuit. If it were 18 up to 14 I might say no, but 12 down to 14 in my book is ok to do. Also there may be (probably is) more than just that one light on the light circuit which would push me to using the unused wire.

[powercat_ras]

Any gauge 14 or larger will be fine. The fan itself will draw 5 amps or less, so it shold be fine on any circuit. The only reason the wire needs to be at least 14 is because the circuits are likely fused at 15 amps.

[Goodspike]

I'm going to assume the fan is a 12 volt device. I'm not sure what that line is for the water heater you don't have, but you should make sure whatever line you use is the correct voltage.

[Motts461]

Yes the fan is 12 volt and both lines are 12 volt. Both circuits are fused at 15 amps. I thought I was safe either way but thought I would throw it out here to get some different opinions, Thanks