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Thread: Does this seem high? Can I do this by myself?

  1. #1
    DIY Member ironspider's Avatar
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    Default Does this seem high? Can I do this by myself?

    Greetings all,

    The wife and I just bought a new house and during the electrical inspection the inspector noticed that something was not correct in the way the barn (detached about 75 feet from subpanel to main service panel) was wired. I think he said they had used 3 wire instead of 4 wire and there are no grounding rods at the barn. The current wiring is fed through conduit buried in the ground.

    So, after the inspection, we had a couple of local electricians come by and do their estimates on fixes. We had some other fixes in this as well such as an A/C disconnect and a service upgrade to 200AMPS from 100AMPS. Both electricians had that line item (replacing the wiring to the barn and doing the ground rods) at around ~$850. That seems like a lot to me.

    So, my question is whether or not I can do this myself. Now I know that any time someone asks a question like that, pros are going to have visions of exploding houses and DIYers running around with flames on their backs but I have done a lot of electrical before in our current house (by a lot I mean that I've run several new circuits and understand the process [not that I am a master electrician or anythign like that!]). Am I missing something here? This is what I *believe* would need to happen:

    Purchase materials: (60 AMP sub panel and breaker in main box and conduit already exist) so 75x4 (2 hots, neutral, and ground) = 300ft of #6 THWN @ $0.60ft = $180. 2 grounding rods = $30. Grounding clamps = $6 total ~$215.

    Labor: obviously free since I'd be doing it. I know this might be a lot of work but it's still free if I do it myself.

    Permits/Inspections: Now I have no idea about this part of it. I assume the township wants to inspect work like this to make sure you aren't going to blow your house/barn up but does that usually cost money? And does obtaining a permit usually cost money? Is a permit even needed, or just an inspection?

    I don't know if I'm missing anything there but that seems like my elbow grease could save me around $600.

    Am I missing somethign here? Are those higher numbers from the electricians because of the labor to pull that wire and some padding in case they need to dig anything up?

    Thanks!

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    Plumbing Designer FloridaOrange's Avatar
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    Quote Originally Posted by ironspider View Post
    Am I missing somethign here? Are those higher numbers from the electricians because of the labor to pull that wire and some padding in case they need to dig anything up?

    Thanks!
    I'm not an electrician but just wanted to comment on the statement above.
    Labor+permit+insurance+license fees+business occupational licenses+etc.
    There's usually more cost involved besides someones hourly pay.
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

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    DIY Senior Member Jeff1's Avatar
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    I'm not an electrician either but have done a lot of this work (taught to me by my uncle who was an electrician). You may also have to change the conduit which could include digging and either bending or gluing. A big question is: how much is your time worth? I just had to re-do some work done by a pro. It took me 2 hours and a couple runs to the hardware store. I'm sure a pro could have done it in half the time. (The pro replaced a sub panel and didn't do a very nice job with the wires entering the panel. It also didn't have a separate ground wire - old work).

    The actual work is not rocket science, but it is labor intensive. If you are not sure you might want to have the pro do it and pay for the piece of mind. Just make sure you both agree on the total work to be done.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    You'd need to determine the fill rate of the conduit to see if it could support an additional wire. Pulling that much through a conduit can be grueling if there are any bends. Add in some wire lubricant...you'll need it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades mattbee24's Avatar
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    Maybe I'm missing something here, but since it is an un-attached building couldn't he just put in a ground rod at the barn and run a ground wire from the rod to the panel? Of course, he would still have to make sure the grounds and neutrals are separated in the box.

    I always thought that is what you were SUPPOSE to do when you have a building is not attached.

    But maybe I'm just plain wrong...it's been known to happen.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    A subpanel is to be boned at the supplying source, thus you are supposed to have 4-wires. At a sub-panel, ground and neutral are supposed to be separated in the panel. Will it work, yes, is it as safe as it should be or meet current code, no.
    Jim DeBruycker
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    In the Trades mattbee24's Avatar
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    Not trying to argue here jadnashua, you probably are more familiar with this than I am. But isn't it only required to run 4 wire from the main panel to the sub when the sub is within the same building?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Not sure...one of the pros will likely pick up on this later. It was my understanding that a subpanel was wired the same, regardless of whether it was an attached building or not.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Code Enforcement codeone's Avatar
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    Quote Originally Posted by mattbee24 View Post
    Not trying to argue here jadnashua, you probably are more familiar with this than I am. But isn't it only required to run 4 wire from the main panel to the sub when the sub is within the same building?

    Under the 2005 NEC it allowed you to use the grounded conductor to be connected to the seperate building disconnecting means and the grounding electrode. The 2008 NEC does not allow this you have to run a seperate grounded conductor and a grounding conductor. Article 250.32 However there is an exception.

    The exception states. For existing premises wiring systems only,the grounded conductor run with the supply to the building or structure shall be permitted to be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding and bonding of equiptment or frames required to be bonded where all the requirements of (1),(2) and (3) are met.

    (1) An equiptment grounding conductor is not run with the supply to the building or structure.
    (2) There are no continious metal paths bonded to the grounding systems in each building or structure involved.
    (3) Ground-fault protection has not been installed on the supply side of the feeder(s)

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    In the Trades mattbee24's Avatar
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    If I am reading that right, you used to be able to use a ground rod but now you have to run the ground from the panel? Unless it is an existing structure, then you can use a ground rod?

    Why was one way safe in 2005, but not in 2008?

    I guess that's why you guys take all those damn classes. It sure does confuse the hell out of me.

  11. #11
    DIY Member ironspider's Avatar
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    Thanks for the replies, as always on these forums I love that it gets some good thinking and talking going!

    I'm going to keep checking this to see where the questions immediately above this reply go but, if I did do the work myself, I think I would be using the THWN2 cerrowire from Lowes to do the work. On the Cerrowire page, their ampacity chart says that #8 THWN2 will support 55AMPs. Now, if I recall, since there are no 55AMP breakers, you are allowed to use a 60AMP breaker on something rated for 55AMP correct? (I think this is written as "protected to 60"). #6 wire will support 75AMPs so, obviously, there would be no issue in using that for a 60 AMP subpanel. I most likely would just use the #6 since it is only .06 more a foot but I just want to know exactly what is allowed.

    Also, would the ground I run from the main service panel have to be a #8 as well (if I used #8 wire) or a #6 (if I used #6 wiring for the other 3 wires [hot, hot, neutral]) or could it be smaller? I ask because when I look at some 6/3 UF-B romex the wires are obviously 6 gauge but the listed ground is 10 gauge. Now that would be a savings if I could use #6 for the 3 hots and a #10 for the ground because the #10 is almost .20 cheaper a foot.

    So, in summary, would this be the least expensive "meets code" way to do this: Buy 3*75' each of THWN-2 #8 [red, black, white]and 1*75' of THWN-2 #10 [green], 2 grounding rods, and two grounding clamps?

    Then disconnect the run at the main service panel, connect the 4 wires from the wiring caddy to the existing wire, tape them together, lube it up and pull it through on the barn end and pray to god it's a straight run?

  12. #12
    Retired Defense Industry Engineer jadnashua's Avatar
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    As you can see, it depends on what code your area uses, so the first thing it to check with the local inspector to find out...then follow it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  13. #13
    Electrical Contractor jbfan74's Avatar
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    #8 wire is rated at 55 amps in the 90 degree column, but you will not find any breakers of lugs rated at 90 degrees. This column is used to derate the wire.
    Most cases you would use the 75 degree column to size the breaker, in this case 50 amp.
    If you want to run 60 amps to the barn, you will need #6 wire. You can use #10 for the ground.

    You also need a min. of 3/4 conduit to pull these wires.
    Yes I am A Pirate-Jimmy Buffett

  14. #14
    Electrician ActionDave's Avatar
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    Quote Originally Posted by mattbee24 View Post
    If I am reading that right, you used to be able to use a ground rod but now you have to run the ground from the panel? Unless it is an existing structure, then you can use a ground rod?

    Why was one way safe in 2005, but not in 2008?

    I guess that's why you guys take all those damn classes. It sure does confuse the hell out of me.
    all structures require a ground rod. it is connected the grounded bus at the service but to the grounding bus when you have a sub panel if it is fed four wire.

    that's not exactly true. all structures require a grounding electrode system which commonly consists of a ground rod and water pipe. sometimes you need only one ground rod, a lot of times you need two. sometimes you don't need any ground rods.

    under '05 or '08 you must feed a sub panel with a separate equipment ground if you have a metalic conection between the two buildings.

  15. #15
    Licensed Electrical Contractor Speedy Petey's Avatar
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    First off this is yet another case of a H-I not knowing what he is talking about.
    It is quite possible that this is a code legal installation. NO, not all feeders were required to be "3-wire" with the grounds and neutrals separate.
    Codeone gave you the earlier supporting code section.

    Also, yes, any detached structure served by a feeder requires a grounding electrode of some sort. This is not required if the structure is served only by a circuit.

    Jbfan gave you the lowdown on ampacity. You CANNOT simply go to some website and look up conductor ampacity, you will get it wrong 99% of the time unless you know what you are looking at.
    To add to what Jbfan said, if you are looking to use SER or even NM cable, such as UF, then you are limited to the 60 deg C column which lowers the ampacity even more.
    Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.

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