Length of electrical run to shed?

[rbstern]

I'm putting up a 12x20 shed to hold my lawn and garden gear. Trying to decide if I should run a 20A/120v direct bury cable to it from my home. It's about 250' from the electrical panel in my basement, but to route in a to avoid septic lines, buried electrical service and phone, I'll have to run about 350 feet of cable.

Any practical reason not to do this? Is it too far for a 120v line?

EDIT: Sorry, should have specified...usage will be for some LED lighting inside and out side the shed (very low amperage), and for one standard outlet that will be used for battery charging, maybe the occasional power tool up to 10 amps or so.

 

[truckdiagnostics]

You should be able to go over the top of your septic, its not like you "need to go that deep". Conduit going into structure and out 6'. Put it in a ground fault breaker. Plow the 12awg direct burial and be done with it. Then use a 15 amp ground fault breaker. Your not pulling that many amps, so you shouldn't get a voltage drop.

 

[mddorange]

I hear what you are saying, but it has been my experience that there will always be wattage creep. Do yourself a favor and go ahead and run 240v NOW and save yourself many more problems later.

 

[rbstern]

The long route avoids everything. If I go over the septic system, I also have to cross buried phone cables, which might be shallow enough for a problem.

 

[Mendonsy]

Here's a calculator that will tell you what wire size you need to run for the current and distance. The answer seems a bit high, but I tried several different ones and they all came up the same.
Wire Size Calculator

 

[Sodo]

For 350 ft need 8ga to run a 10A tool. Using 12ga you can run about 3 Amps of load. 12ga is plenty good for LED lights or a 30A battery charger. Maybe consider 10ga and run the 10A tool carefully, don't push it too hard.

 

[rbstern]

I hear what you are saying, but it has been my experience that there will always be wattage creep. Do yourself a favor and go ahead and run 240v NOW and save yourself many more problems later.

If I go 240v, direct bury cable is against code and I have more expense and effort to bury the line in conduit. I can live with 120v and limited amps. Any type of work needing more than that will get done near the house.

 

[dieselcrawler]

I have been a licenced electrican for nearly 20 years. Anything over 100' from the breaker to the recptical needs to be up sized for the voltage drop. If you are worried about code compliance (not running 120/240v direct bury wire) then the smallest breaker for a general purpose branch circuit alowd by code is 15 amps, you still need at least 10ga wire. I would go with 8-3 w/ground, and be able to get a useable 20 amps 120/240 volts out there. Do it right the first time. But then, I would also run a larger conduit in as straight a line as possible. Hand dig around the phone lines if needed. Code says conduits and wires "should" be 18" below the surface and have warning tape buried 6" below the surface. There may or may not be a type UF wire run to my pool area 3-4" below the surface of my yard. Out here in the country there is only me to make me comply with code.

 

[grsthegreat]

Is it a local law that forbids 240 direct butial? Its not against NEC rules. After 100 feet derate occures, and it doesn't matter what the use is. Probably doesnt matter if your only using lights, but the derate will play **** with motors like drills, refrigerators, etc.

 

[rbstern]

Is it a local law that forbids 240 direct butial? Its not against NEC rules. After 100 feet derate occures, and it doesn't matter what the use is. Probably doesnt matter if your only using lights, but the derate will play **** with motors like drills, refrigerators, etc.

Going 240v means I've got to go to 24" deep or do conduit.

I really only have two uses for power at the shed: Battery charging and lighting. I considered going with a solar setup, but I don't want another 12v battery in my life (have too many of those already).