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New 30 Amp Shed Sub Panel underground electrical feed. - Should I use 10/3 UF-B or 10/2 UF-B and is

Post in 'DIY and General non-hearth advice' started by Don2222, Nov 26, 2011.

  1. Don2222

    Don2222 Minister of Fire

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    I never said it was a 150 foot run, just that I purchased 150 ft of wire which was very much over estimated. The house is 42 feet long and the trench is 27 feet long but it also goes 10 feet up the side of the house and a few more twists and turns to get to the circuit panel. Maybe 100 foot should have been purchased. Just not a good estimate.

    Anyways, I wanted to ask you BeGreen if I put two 20 Amp Breakers in the sub panel. Then would the 30 Amp breaker in the main panel still be enough?

    Thanks again
    Don

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  2. nate379

    nate379 Guest

    30 amp in the main panel is correct for the #10 wire.

    If you put 20 amp breakers in the sub panel you need to use #12 wire on those 2 breakers. Or could use #14 wire and 15 amp breakers.
  3. nate379

    nate379 Guest

    30 amp in the main panel is correct for the #10 wire.

    If you put 20 amp breakers in the sub panel you need to use #12 wire on those 2 breakers. Or could use #14 wire and 15 amp breakers.

    What are you powering in that shed? If it's just a few lights/outlets, I would not run a panel and just do everything on one circuit. This is legal to do.

    A #12 wire would be fine for that as well.
  4. oldspark

    oldspark Guest

    I dont know if code will allow 2 20 amp breakers on one 30 amp breaker. When ever I wire in a building like you are I always try and go bigger so down the road I am covered but depending on what you are running in the shed you should be fine I would think. Do you have to follow a code in your area?
  5. Don2222

    Don2222 Minister of Fire

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    Hi Nate

    Not sure what I will have in the shed. A table saw and a sliding mitre saw plus outlets and lights. Also a heater.

    So I though since the box has two slots I may as well use them.

    One last question?
    Since I am using underground wire UF-B is it acceptable to protect the wire before it goes into the ground with a little conduit??
    See picture below:

    P.S., The second wire is 14-3 to a 3way switch in the house so I can switch on the lights before I go to the shed at night! :)

    Attached Files:

  6. nate379

    nate379 Guest

    The #10 wire feeding the sub needs a 30 amp breaker and if 20 amp breakers are in the subpanel, those circuits need to be #12 wire.

    Add up the breakers in your house panel, it's going to be more than the main breaker. Figure avg house with 100-125 amp service.

    Electric dryer 30 amp, electric stove 50 amp. Dishwasher 20 amp, kitchen outlets, 20 amps each, 3 bedrooms, 15 amps each, living room 15 amp, dining room 15 amp, fridge 20 amp.

    I'm missing a bunch of stuff but that is over 200 amps just right there.





    Don yes you can run it in conduit. You can do the whole think or just like you have. That 14-3 is UF wire as well? You can do other types of wire but they will require a full run of conduit.
    The UF wire doesn't like UV rays, though some of it now does have that rating I believe. I worked on a building some years back that they owner had stapled the UF to the side of the building and


    I would also put a 90* sweep on the bottom in your pic so the wire isn't kinked
  7. nate379

    nate379 Guest

    Oh while doing some reading for this thread I realized that it's ok to run UF wire indoors.

    Again mis-information from a "pro" master electrician. I was told that I had to convert to Romex indoors. The run I did for my shed I went about 40ft across my attic in the garage with reg Romex, down the wall and then tied into the UF wire at the LB connection on the outside wall. Then did the same at the shed about 100 ft across the yard. Granted that is still ok and romex is much easier to work with and cheaper, but it still annoys me that I got bad info.

    When I moved into my new house I found that they wired my panel from the meter panel which is on the other side of the house with #4 aluminum wire. All that was on a 125amp breaker!! #4 aluminum is only rated for 75 amps!
    They ended up having to pull that wire out and replace it with the correct wire.

    I realized I wasted 300$ on a home inspection when I had to tech the inspector how to look for aluminum wiring. Really???
  8. Don2222

    Don2222 Minister of Fire

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    Thanks for the correct info Nate.

    I am running the UF-B thru the ceiling in the garage and basement to the other end of the house where the main panel is. What a PITA!

    I just took the 90s out at the bottom of the trench because I did not want any moisture collection?
  9. Don2222

    Don2222 Minister of Fire

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    Hello oldspark

    Yes I am following the code in my area but connecting to my main panel will be tight. (No more open spaces) However I know what I use and do not use so I know I can sneak the 10-3 in with no trouble. An inspector would probably force me to a 200 amp panel and I cannot afford that right now.

    I really need the 2 circuits in the shed. If I run my compressor and have the heater on, I would pop one breaker.
  10. Don2222

    Don2222 Minister of Fire

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    Hello

    Thanks again guys, I took your expert advise and returned the 15 amp breakers for the 20 amp breakers!! I would have never know that! You guys are great!!

    See pic
    1 - 15 amp breakers
    2 - 20 amp breakers

    Attached Files:

  11. begreen

    begreen Mooderator Staff Member

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    Well you are not going to like me saying this, but that top romex clamp should be entirely on the outer jacket insulation and not clamping on the wire. If you cut it too short, at least wrap some electrical tape around the wires where the clamp is.
  12. Don2222

    Don2222 Minister of Fire

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    Thanks BeGreen

    I appreciate you saying that and suggesting the Tape. I will do that. It is difficult working with that size wire. I had to cut the Load wires shorter than the ground and neutral so they would reach the connectors.

    I was wondering about the jacket and clamp. I will do that thanks again.

    BTW. I found this nice chart.

    http://www.wireityourself.com/wire_sizes.html

    See below and click to enlarge

    Attached Files:

  13. Don2222

    Don2222 Minister of Fire

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    Hello

    One more question for the road.

    I hooked the sub panel into the main panel today. The shed has it's Juice!!!

    The main panel had a 220v 15 amp breaker for the 220v 900 watt kickspace heater in the pellet stove hearth for basement heat if the pellet stove is down. Rarely if ever used. Also on that 15 amp 220v breaker is the central vacuum. The 220v central vac has 70cfm of suction with 2 motors and dual exhaust. I was running straight pipes until my neighbors complained then added mufflers!! Anyways it pulls 11 amps!! The kickspace heater pulls 6 amps.

    So when I tied the 30 amp sub panel with 20 amp breakers in it to this point and I added a 40 amp 220volt breaker in place of the old 15 amp 220v breaker

    So if you add 11 + 6 + 20 = 37 amps in which I will never have everything going at once, It should be right!!

    My question is this the best way to do it?


    See picture below. Meter set to 250 vac scale and needle is approx half way. :)

    Click on pic to enlarge

    Attached Files:

  14. nate379

    nate379 Guest

    Ok I'm not sure I'm following 100%

    In your main panel you had a 15 amp 240v breaker that powered a heater and a vac.

    Then you pulled out that 15 amp breaker, put in a 40 amp breaker and put your sub panel on that too?

    If that is what you did that is not correct at all.

    First in most all locations you can't double tap a breaker like that.

    2nd a sub panel needs to have it's own breaker in the main panel.

    3rd tThe 10-3 wire you ran to your sub is only good for 30 amps, so it needs a 30 amp breaker in the main. If that 15amp run is wired normal it would be a 14/3 wire, rated only for 15 amps.

    That 40 amp breaker would never trip unless you had a complete dead short. If either the subpanel run or your other run would be overloaded the wiring will melt down and could burn the house down... the breaker would probably never trip.


  15. begreen

    begreen Mooderator Staff Member

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    No, sorry to be blunt, but you are dangerous around electricity. The breaker gets sized to the wiring, not the estimated combined load of multiple circuits that were wired at a lower load and wire gauge.. You have created a dangerous situation in your house. Splicing 3 circuits of mixed wire gauge onto one higher amperage breaker is not allowed and very unsafe. I shudder to think what this panel must look like. For the safety of your home you should get a professional electrician there to review this.

    I see now that there is plenty of slack to do that top romex connection correctly. Insert it deeper into that connector so that it is clamping on the insulation. And last, I see the neutral bonded to the ground at the sub-panel. They should be separate.
  16. davmor

    davmor Member

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    You cannot have your subpanel ground and neutral bonded. It appears that is what you have done. Not sure on your questions. Maybe a picture of your main panel may help. If you are not sure of your work you may be farther ahead to have someone look at it.
  17. Don2222

    Don2222 Minister of Fire

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    Thanks BeGreen
    I need to upgrade to a 200 amp main panel to correct that. Thanks again
  18. gpcollen1

    gpcollen1 Minister of Fire

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    Just want to make sure you do not leave it like that?! You need to put those breakers back the way they were...OR...you can get special breakers where you can get 240 from a 'single' breaker or 2 - 120 lines from a single breaker. That is what you need to do if your breaker space is all used up. Not sure what brand panel you have but here are the Square D Tandem Breakers...

    http://www.nextag.com/square-d-tandem-breakers/stores-html
  19. oldspark

    oldspark Guest

    I was worried about this happening, no disrespect to any body but advice off of a forum for electrical is not good, I mentioned the breakers a while back and it sounded wrong but sorting out the good advice from the bad is not always easy when you are not sure.
  20. oldspark

    oldspark Guest

    I hope not as it has been beat to death in this thread, I can not tell for sure from the picture.
  21. Don2222

    Don2222 Minister of Fire

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    Hello

    I appreciate all the info I got from this thread there is alot of good information here to keep me going down the right path. An upgrade to 200 amp service and a few breakers will make this all correct! Thanks again for all your information!
  22. Don2222

    Don2222 Minister of Fire

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    Attached Files:

  23. davmor

    davmor Member

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    If you click on the picture it enlarges it. It looks like the the neutral and the ground are on the same bus bar.
  24. oldspark

    oldspark Guest

    Right you are, don2222 did you catch that, that is a no no and mentioned in the thread many times. The one link I posted had every thing covered for a sub panel. Good eye davmor!
  25. Don2222

    Don2222 Minister of Fire

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    Hello oldspark

    Yes, but was not clear about why. So these two links explain it! Thanks for pointing me in the right direction!
    There is an optional ground buss for this panel and it did not explain anywhere what this option was for!
    I now understand the extra buss is for equipment ground that this panel feeds that should be connected to a ground rod outside the shed!!!
    What I need that can be purchased at ACE hardware is:
    http://www.acehardwareoutlet.com/productDetails.aspx?SKU=36347
    Then a ground wire must be attached to this ground buss outside the shed!!

    from http://masterslic.tripod.com/FAQ-2/18.html
    Why isolate the neutral in a sub panel?...
    The neutral is only bonded to ground at your service panel. At all other points throughout your house, there is no connection between the bare (or green) grounding conductor and the white neutral conductor. Under normal conditions, the grounding conductor carries no current. No current means there is no voltage drop along it, therefore anything "grounded" to this conductor is at the same potential (voltage) as ground. If you bond the neutral and ground at the sub panel, then stray currents from the neutral return could go thru the equipment ground on the electrical devices fed from this sub panel. If you isolate the neutral and ground at the sub panel, than any currents would go back to the main panel, and go to the service ground. The main panel is where the neutral and equipment ground should be bonded.
    If you install a sub panel outside the building from the main panel, than you will need to drive a ground rod at this panel. A single branch circuit run to another building is not considered a sub panel.

    also from here >> http://ths.gardenweb.com/faq/lists/wiring/2005015726007600.html

    Grounding and bonding of the sub-panel

    At the sub-panel there must be no connection between the neutral bus bar and the equipment ground bus bar or the neutral bus bar and the sheet metal of the breaker box. You may need to purchase an additional bus bar for the equipment ground since many panels, especially those that come with a main breaker, do not come equipped with one. If the panel comes with a bonding screw or bonding strap, do not install it to the neutral. Depending on the brand of panel, you may need it to connect the ground bus to the sheet metal enclosure.

    At the remote building, you will need to drive two eight-foot ground rods located a minimum of six feet from each other and connect them to the equipment ground bus using #6 copper wire. The easiest way is to make one continuous run without cutting the wire. The rods must be driven in flush or below grade. The ground rod clamps must be listed for direct burial. It will say so on the clamp or look for the letters "DB". If you have any metal piping (except gas lines) in the remote building, you must bond it to the equipment ground bar, use #6 wire. If the connection is to a metal water line, the connection should be within the first 5 feet of where the water line enters the building. All connections must remain accessible, so if the connection will end up inside a wall, you must provide an access plate.

    I realize that some of the things I've included exceed the code minimum, but this is an attempt to make a "one size fits all" response without getting into a really long discussion.

    For a sub-panel in the same dwelling there is no need for additional ground rods or connections to metal piping. Also, no need for a main breaker in the sub-panel, regardless of the number of circuits. Unless you are running metal conduit, you will need to run a 4 wire feeder.
    ------------------------------------------------------------------------
    Ace Hardware Equipment Ground Buss for Sub Panel in shed!

    "SQUARE D" GROUND BAR KIT



    For attaching ground wire in load centers and safety switches
    Required when load center is not at point of service entrance
    Has 12 lugs in grounding bar
    For wire diameters between 4-#2/0 AWG maximum
    UL listed
    Clampack
    Fits Ace No.s 32537, 32538, 34034, 34035

    Attached Files:

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