My garage was built in 1937. It has the original wiring that terminates in a four-way receptacle box. But for some reason it has stopped working. We bought the house with a updated breaker box doesn't show this line to the garage.

No breakers are tripped, I put a tester on the receptacle in the garage and it doesn't register anything. It has worked for the past 14 yrs. And now nothing. I have four 8ft. Fluorescent and a garage door opener.

I was considering running a new line to the garage and putting in another breaker. The box is made by Sylvania (200amp) service and I was thinking about a 20amp breaker.

Can I run UF 18” deep to the garage under the siding and to the existing four-way receptacle box?

The breaker could be defective, even thou on or not tripped. Checking this will require you opening the panel LIVE, this must be done by someone that knows exactly what to do.

Could be a break in the cable or a loose connection at a junction box between the panel and the garage.

Is a detached building, and the cable is underground?