Posted: 12/15/2007 9:43:52 AM EDT
| I have a 240 V. sub-panel in my back shed that has only 1 lighting and plug circut on it...Ide like to run two seperate circuts out to my shooting shed for a light, and a few plugs.. If I have 10-2 UF AWG for a 100 yard run out to the shooting shed. Can I use the insulated ground as a neutral and put 2 hots on seperate phases for 2 15 amp circuts? |
|
You can run a multiwire circuit with 2 hots, 1 neutral, and one ground. This is the only legal way to have more than one circuit in a detached structure. The NEC considers a multiwire circuit as a single circuit, even though it has two separate 120 V hots. You MUST make sure the hots are 240 V between them to have the circuit work correctly and not overload the neutral. |
|
You might own the UF cable already, but IMHO you'd be a LOT better off to bury a conduit and pull the conductors you need. Determine what you'd like to run and do a little load and voltage drop calculating for that distance. It might cost a little more but I'd bet you'll be glad you did it right. Stay safe |
|
Yes, but that's my point ... you're going to go through the work of burying something that is hardly adequate to begin with. IF ... you've got to bury it anyway, why not bury a long (PVC?) run of conduit and easily pull in conductors that will feed what you want ? Romex and UF are so common/universal nowadays that people forget how convenient it is to change/repair/upgrade when the run is in pipe. My 2c. Only you know if it's worth it, but it could be another option. Stay safe |
|
Conduit also has the advantage of allowing the conductors to be replaced when lightning fries them. The conduit (especially metal conduit) is rarely damaged but the conductors can have the insulation destroyed by a strike even nearby. The huge magnetic field from the current couples into the lines and destroys the insulation. We have had problems getting damaged wires out, but it is still less work than a complete new installation. |
|
Do I have this right? 1. You have a panel in your "back shed". 2. You want to run wire from there to your "shooting shed" that is 100 yds away. Question: is the panel that supplies your "back shed" closer your "shooting shed"? If so, take the power from there, But as other have suggested - and to add on - I would run PVC from a panel into the shooting shed - but have it feed a small 6 circuit You can run bigger wire - like #6 or something similar - and have 6 circuits for future use. I'm a big fan of 'plan for the future'. It's generally cheaper, and MUCH less of a PITA. And to put the first step last -  - you need to figure out what the load in your "shooting shed" will be before deciding what size wire/breaker to use.
I'm gonna say don't so this. If I'm reading you right, you won't have a ground in your "shooting shed". That's a bad thing. |
|
^^ I agree with above poster. It would be the best to plan out what you want and do it right the first time. According to the NEC, you need a grounding and a grounded conductor, so your 10-2 won't work if you want it to meet code. Figure out what your power needs are going to be and go from there. You can use the UF you have, but PVC conduit would be a better option. 
|
Not correct for a separate structure under certain conditions. If you install a sub panel and there are NO OTHER METALLIC CONNECTIONS (like water pipes, phone lines, etc) to the shed you can run a 3 wire service (hot, hot, neutral). The shed will REQUIRE ground rods. A 4 wire service is still safer (hot,hot, neutral, ground) but ONLY required if there is another metallic connection. A small panel fed by a 30 A 240V breaker would likely support whatever you want except large motor loads. You could even use a main lug panel in the shed as long as you can turn ALL the circuits off with 6 moves of the hand or less. I personally would use a main breaker since it makes it easier to kill the panel bus to work on it when needed without trying to install a lockout in a residential panel feeding the shed. |
|
I'm not an electrician but dable in it a little... it seems it would be 'better' to ground the building and electrical with ground rods at the sight than rely on a seperate grounded line (4th wire) running way back to somewhere else. I like the conduit idea but sometimes somethings just are practical for the application. Oh and I would not for sure try to run any kind of electrical appliance or high end tool off those circuits, there is going to have to be somemore voltage drop.... 100yards from what is already a subpanel...how far from the transformer? |
1) Said 240v sub-panel has how many Amps feeding it? (Major importance) It must be fed by a large enough breaker to branch out to your shooting shed. 2) 10-2 will carry 120v@30Amps (you should never use your bare ground as a neutral, but can be done) Insulation saves lives! 2b) 10-2= (1) 120v@30A circuit or 10-2= (2) 120v@15A circuits 2c) You shouldn't have much of a problem sharing the Neutral to two circuits, being that the Neutral is 10ga wire and will hold for 30amps, if your using two 15amp circuits, you should only be able to reach 30amp max anyway. When you turn something on with a motor is when your gonna pull Hard on the Neutral. 3) UF is as good as stranded wires in a conduit, if you do things right to begin with. (although FL is the lightning capt. of the world) 4) You can always drive a 2nd ground rod at your shooting shed. PS. Conduit has it's advantages over UF wire, but will cost more! It really depends on your budget and time frame to complete said project. |
The 4 wire service is BETTER than trying to rely on ground rods. Ground rods and the earth connection they provide are NOT effective at 120 V. The grounding electrode system is for lightning and transformer leakage (7200 V primary, or even higher). Ground rods are allowed to be as high as 25 ohms to earth. In a 120 V system you could pull as little as 4.8 amps. The 'worm getter' (now banned by CPSC) used two rods driven into the earth and then plugged into an outlet (non-GFCI). The current would drive the worms to the surface. A bunch of people got killed by the things, but the breakers rarely tripped. |