from my house I am running 300 ft of buried cable. for lights out side. 30 amp breaker. what size wire should i use
300 ft is quite a runlow voltage lighting would be best suited for landscape lighting but .your burial is regulated by nec code it's not 3 feetyou don't need tape to mark it unless.it is a service conductor not encased in concrete and is 18 inches below grade,then warning ribbon should be placed 12 above the installation. your question is fairly opennumber of lights?,type.?,if you want to use 30 amp breaker.residential code will only allow 20 amp ?wire size should not exceed 10awg. UF,you'll need a GFIC breaker ,unless you undermine streets driveways or roads,you'll be within code at 12 depth(nfpa 70 300.5 D.) do some research on low voltage wiring,try to shorten your wire run etc.
Whoa! Where are you? What kind of lighting? What voltage? 300' total run, or distance to 'center of load'? In U.S. the largest multi-outlet residential circuit permitted by Code is 20A. period.
You are working from the wrong direction. What is the draw of the light fixtures? When this and the voltage are known, then the wire size and line loss can be computed then the breaker size is fixed to protect the wiring and the system. The best solution is to call a qualified professional electrician to do the work. The trench for the wire needs to be at least 3 feet deep and buried properly with warning tape over it. In general a 10 ga wire can be protected by a 30 amp breaker, but the 600 foot run means a large line loss and that means a larger wire is needed.
