I have a GFCI with a waterproof cover that I ran outside to the end of my yard on a fence post so I can plug in a bug zapper or have a powered outlet if I need one when BBQing or hosting a get together. I used Type UF-B 12/2 and ran it 2 feet underground and then into my garage to a light switch then from the switch to my main house panel. The switch is so I can have the bug zapper plugged in and just go in my garage and flip the switch to power it, instead of walking all the way outside each night I choose to have it on. I have everything wired up and done except I have not added the wires in the panel to a breaker yet. I was going to buy a 20amp because I didnt really think about it but someone told me I should run something like that to a 15amp instead. I didn't really understand the reason why, but he made it sound like I could somehow damage the line by using a 20amp instead of a 15amp because it would send it more power. But my understanding of power is a 20 amp LIMITS it to 20 amps but it doesn't matter if I have a 20amp or 15amp. As an example, If i have a device that draws 10amps it won't matter if I have a 20 or a 15 connected to it because it should only draw the 10, so I just thought a 20 would be on the safer side for a industrial type bug zapper. (Correct me if I am wrong please)

I don't claim to be an expert on electrical but I think my friend is an idiot so I just decided to confirm if it matters what breaker amp I buy to attach to my panel.

 

When it comes to safer.... a 15A is safer than a 20A breaker as it will trip quicker on an overload.
However.... with #12 wiring..... you can use a 20A breaker safely.

 

Thank you for the reply PJmax, I think I read that my bug zapper draws 4amps so if from what you are saying, if that is the biggest thing I ever plan to have plugged into it I should go lower, even maybe to a 10 amp for safety? I was thinking about running a heated dog bowl during the winter for my ducks but I doubt that would draw more than 10 amps.

 

Can you estimate the length of the entire run. Receptacle to breaker?

 

Most appliances and devices are rated to be plugged into a 15A or 20A circuit.
So there would not be a need to size the circuit for a particular device or load.

 

You are right! .........................

 

I want to say close to 135 feet

 

Put a 20A breaker on that new line. This way if in the future you want to plug something in a little larger..... you don't have to worry about a breaker tripping.

 

Trying to pull 20A on a 135foot line can result in burned out motors. 8% drop in voltage. I strongly recommend 15A breaker and 10 awg wire.

 

He already ran the 12-2UF.

 

If he is pulling 20 amps on the circuit the breaker will likely trip anyway. The voltage drop depends on the actual load on the circuit which has been established at about 10 amps which calculates a voltage drop of 3.5% @ 120 volts.

 

Like PJmax said, I already ran the line. The biggest thing I plan to plug into it (as of right now) is a 100 watt bug zapper so I would be skeptical if a 20 amp tripped over that. But then again, I am not a professional.