Wiring a shed

Discussion in 'Shop Talk' started by Jena, Sep 14, 2006.

  1. Jena

    Jena Well-Known Member

    Aug 13, 2003
    I once upon a time re-wired my whole barn, but it's been awhile...

    I have this shed. Here is the existing wiring...

    an old electical cord comes from the house, is spliced in the middle with black tape to some exterior wire that runs into the shed. The wire is spliced, without so much as electrical tape (yeah, I know...serious hazard there) to a wire going to an outlet and a switch/light.

    I am not touching the overhead thing. If I do, I will end up getting myself into a whole bunch of other trouble that I can't deal with right now. One thing will lead to another and I'll have a major project on my hands.

    I am thinking I need to put a little box in the shed...just like 20 amp with one circuit on it. Just enough to run a couple lights and an outlet for power tools, and a fence charger. I'd wire the box with the overhead wire coming in and take new wire out.

    I'll have to buy the box, but I still have wire and stuff left over from my barn. I forget the wire size, but it is like 12 I think...heavier than your average household wire. So that wire is ok, right? I can always go bigger, just not smaller, right?

    I'm thinking I don't even have to have the box, but I'd rather have it so that if I short something out in there, it stops there, as opposed to frying that overhead wire and going to the house. Is that the right idea?

    I know I can do this...shoot, did that whole barn and it's still standing!

  2. skruzich

    skruzich Well-Known Member

    Jul 23, 2003
    what your talking about is a subpanel,but i don't think your going to be able to use romex to patch into it. Your going to need to run 4guage wire to the subpanel from your main box, and it has 4 wires. 2 hot 1 neutral and 1 ground
    Depends on where you live too, code is going to be the thing tofollow cause if you cause a fire it will invalidate your insurance policy if the wiring is found at fault

  3. countrymech

    countrymech Well-Known Member

    Nov 28, 2005
    Central Wyoming
    I tend to be a little more conservative, but if you are going to want a 20 amp circuit then I would run #10 wire. You can use the #12 that you have, just use a 15 amp breaker instead. I have learned over the years to run bigger wire whenever I can since I invariablly wind up increasing the load on the circuits and I got tired of redoing wire runs. Good luck, Paul.
  4. moopups

    moopups In Remembrance

    May 12, 2002
    In beautiful downtown Sticks, near Belleview, Fl.
    Do you anticipate the need for 220 currant in the future? Such as a welder or heavy air compressor? If not then you only need 3 wires, 4 wires are for two hots of 110 each to create a 220 circuit. A 110 amp currant will operate on black, white, and bare wires (sometimes green), black for flowing currant, white for the (unused) pathway back, bare (or green) for ground. Electricity is consumed at the point of consumption, it does not return to the panel but the pathway must be there for it to work. 220 requires a pair of 110 hots, usually black and red, white to the return (neutral) and bare (or green) for the ground.

    How many feet are you going to cover, what is your final needs?
  5. rambler

    rambler Well-Known Member Supporter

    Jan 20, 2004
    What is the distance between your house and the shed? This is vital info, no one can seriously help you without knowing that.

    There is nothing about your current deal that is to code. You would need to start over - mess with it all - to get it to code. Fire insurance & other things will depend upon this being to code all the way. Some places inspect a lot more than others. So is being to code important to you?

    You say the wire leaves the house from an old electrical cord. Does this cord come from a breaker/ fuse box, or do you mean it is plugged into an outlet in your house? Is it 2, 3, or 4 wires supplying 110, 110 with ground, 220, 220 with ground to the shed?

    I'm just going to ignore that cord & wire. You fully understand it is not to code, and so we will leave it alone. It's sure not a good thing as is. I would not sleep at night if it is as bad a setup as I think it is....

    Ok, in your shed, you will need a small breaker box. The little 2-openning Square D would be fine if you only want 110v out there. This is a seperate building, you need a seperate box controlling it.

    You need to run a ground wire from the box to a ground rod driven 6-8 feet into the ground.

    The power coming from your overhead wire (shutter) goes into this box, and you put in one or 2 12 or 20 amp breakers and run your wires to outlets or lights from the breakers.

    If you are feeding this shed with 12ga wire, you can use one 20 amp breaker maybe. No more! It could be much less, if the run of wire is very long. Distance leads to voltage drop which is _very_ hard on electric motors. This is why we need to know the distance.

    If you are feeding the shed with a better wire, then you can do more or bigger circuts.

    Your good 12 ga new wire will be fine for wiring the whole shed inside, can handle 15 or 20 amp breakers with the 12ga wire.

    You really, really, really want that ground wire & rod in the ground very near the new breaker box. You can feed your shed with 2 wires that way for 110v. It comes under an ag exemption. But you _do_ need a path of grounding. Either a seperate ground wire coming in overhead; or at least the ground rod.

    Again, you do understand the feed wire is totally illegal as is, and so you are breaking all sorts of code, and you won't get any fire insurance, etc.

    You understand how difficult it is for people to help you here when you say you are going to start out with illegal, dangerous feeder wires? Really asking a lot of us all. You are setting yourself up for 'issues' down the road.

    My message is just for illistration, if you don't get better help or want to use bad former installations, don't blame me if it goes wrong. Just covering my butt. Hopefully we can get you to add the couple bucks to upgrade the feeder wire as well once you see where you are at for costs.

  6. The Paw

    The Paw Well-Known Member

    May 19, 2006
    Manitoba, Canada

    as Rambler says, the feed wire is the real issue. While you may be capable of adding a box and outlets, all this does is create more potential draw on a suspect feed wire. An electrical circuit is only as sound as its weakest link, and adding outlets on the end of that feed wire is just asking for trouble.

    If the feedwire is not a dedicated circuit, but coming from one outlet on a general house circuit, you may be setting yourself up to overload that circuit by adding too many outlets.

    Do it right. My rule of thumb is that it is okay to improvise on plumbing, because the worst thing that can happen is you end up knee deep in crap, but electricity is a whole different matter. If you describe the feedwire set-up in more detail, I am sure there are knowledgable posters who can tell you what is involved in upgrading the feed wire.

    Good luck.
  7. tiogacounty

    tiogacounty Well-Known Member

    Oct 27, 2005
    you need an electrician. It sounds like you have some questionable wiring installed already and nothin' personal, but you are doing far too much guessing to make me comfortable. On little mistake can burn your shed to a crisp or kill you. is it worth it, to save a few hundred bucks?
  8. Gideon

    Gideon Well-Known Member

    Sep 14, 2005
    Just from a layman's POV I would come off the main panel with 10 gauge to the shed breaker or fuse box then 12 from there. I like heavier wire-makes me sleep better at night. Use conduit wherever posible and please use junction boxes for connections. Wire nuts with tape is better-use proper sized nuts to get tight fits. I like to twist my wires together with pliers first and then put on the wire nuts. May be over kill but that way I KNOW I have secure joints that are not going to overheat and burn the place down. Sounds like your present wiring is just waiting to really hurt someone or your building. I got hit in the head with unprotected wiring once and did not like it-hurt for a month. Could have sued them for the mess-don't expose yourself to that liability-cover that wiring please.
  9. boonieman

    boonieman Well-Known Member

    Dec 27, 2005
    Meade Co Kentucky
    I have to admire you for considering attempting this job. However, in this case, you should strongly consider what Rambler and others have said. At least have an electrician run the wire from the house to the subpanel in the shed and then maybe you can take it from there.