Running Electrical Wires Underground

Discussion in 'Shop Talk' started by billyj, May 5, 2006.

  1. billyj

    billyj Well-Known Member

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    I'm getting read to run water and electrical service to my 5th Wheel camper as temporary service underground.( consider it permanent) because I may have use for it later. I want to get the camper away from the future building site with assurance it want be in the way. My water and power source is next to the where the building will be. So, this means running the power and water some distance (not sure yet) could be as much as 200 feet.

    The reason for the long distance is, my power and water is on the West side of the site and I want to set the camper up on the East side. This means going around the rear end of the site as to not interrupt the plumbing under the concrete slap.

    My questions are, what size wire, type (strand or solid), what type of conduit, how far can I run the wire without a drop in amps. can I run the water and power in the same ditch as long as I separate, where I'm located the word CODE does come up :hobbyhors (the ditch-witch I'm using will dig 4ft in depth).

    Address this project as if you were setting up a campsite. That's what this will be for about a year. Building funds are coming in slow.

    Your input would be greatly appreciated.
     
  2. Rowdy

    Rowdy Well-Known Member

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    Get ready to spend some money... No, really.

    First you need to get an exact number of feet. I'll use 200ft, since it is a number you used, and a figure similar to what I did.

    Personally, I would go with direct burial wire. Conduit is expensive, takes more time to put in, and then you have to pull through it.
    If you are going 200 ft you are going to need something around 2/0. I have not priced wire in over a year, but 200ft of 2/0 three conductor rated for direct burial will be well over $1000 just for the wire.

    Of course, if you are planning it to be _just_ campsite you could probably use smaller wire, depends on what type of amps you want at the campsite. I'll say 70 amps. That will give you 50 for the trailer and 20A for an outside plug. Using 2awg wire that would only be a voltage drop of about 4%. ( I think up to 6% is acceptable, but I am not an electrian, haven't been on a ductbank job is several years) 200ft of 2awg should be under $500, but again it has been a long time since I priced wire.

    What I ended up doing was buying enough 2/0 to get me close enough, put up a sub panel with just lugs and a switch then went down to a smaller wire (I think I used 2awg) for the rest of the run. Cut my wire cost down to under $700. This worked for me in part that the house I am going to build will be close to that subpanel, and my shop will be where my travel trailer is sitting now, so both runs are wire will not be wasted in the long run.

    Personally, I would not put the two in the same ditch. If you ever have to dig up either for a repair it will be alot quicker/eaiser/safer/etc if they were several feet apart.


    Other people here have more recent experiance than I do, it would probably suit you to listen to them, and of course do as much research of your own that you can.
     

  3. WisJim

    WisJim Well-Known Member Supporter

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    What Rowdy said sounds right, but I would put the wire inside some PVC conduit for protection against future digging accidents.
     
  4. copperkid3

    copperkid3 Well-Known Member

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    What they BOTH said is very good advice......and perhaps I can add a suggestion that incorporates a bit of each. It may be possible to use a 2/0 wire that is not direct burial and place it into the gray plastic underground conduit. The water line and electrical can both be laid in the same ditch, provided they are separated by a minimum of 2 feet of dirt. Check on the codes in your area, but around here, the water line is laid first at least 4 feet down to get below the frostline, then dirt is filled in and the electrical is laid a minimum of 16" below ground. Lay the electrical line out along the path that you plan on using and start sliding the conduit over the line; it helps to get the kind with the built-in couplings on one end; glue them as you go and then slide it in and cover. However, Rowdy makes a good point about NOT putting them into the same ditch; perhaps lay the water line first at 3-4' (depending on your frostline) and then move over from the first ditch a couple feet and set the depth to 15"-24" and then run the electrical. Be sure to make a detailed map showing where the lines are; depth, etc. and keep it in a safe place for later reference to the property.....it can be invaluable to future owners!
     
  5. countrymech

    countrymech Well-Known Member

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    If I understand your question right, you want to run power to a sub panel with a 200 foot run. What is the size of the service at the camper. The 2/0 stated would be enough to power a future shop ie 220. Your camper should not be more than 50 amp service. This can be supplied by a run of a #6 copper or #4 aluminium wire. National code for a direct burial cable of this size is 24 in. I do believe. Might try calling your local power company and see if you can purchase wire from their yard. It is usually cheaper than going through a retailer just due to the shear volume of wire they purchase. Good luck.
     
  6. fordy

    fordy Well-Known Member

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    ...................What maybe correct electrically mayNOT be feasable finanically!! The standard RV service is based upon 30 amp\120 volt service . Were it me I'd check into some #8\2 with a ground that is direct bury and should handle most loads that you would require in your camper . Actually , you could run 240 all the way to a fuse box next to your camper location then wire into one of the 120 hots leads and the ground\neutral for the camper , then you could use the Other hot side for tools , lights , etc. Plus I suspect that #8 would be alot cheaper than the "0" size wire . fordy... :)
     
  7. Gideon

    Gideon Well-Known Member

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    #8 should take care of a fair sized camper even at 200 ft. Is the ground rocky? If yes I would use plastic conduit to shield it from cuts. What you may consider is simply laying it on top of the ground this summer until you get the shop built then going underground from the shops panel. The amperage would be better that short distance. We are going to lay electrical and water for about 100yds to the gate so we can water along the drive and provide electrical for the gate motor and camera/monitor. We will put the electrical down first then about 6-8 inches of soil and then the water about one foot deep. Frost line here is @ 6 inchs.
     
  8. billyj

    billyj Well-Known Member

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    Spoke with the guy who' s putting the well in and he said running 10/2 grey wire would be fine ,250 foot roll $126.00 bucks. Since I will be in an area where electrical storms pop up often, he suggested running a second wire and leave it open just in the first wire shorted out,(not likely to happen, but a chance) I wouldn't have to located the short. Code in that area calls for the wire to be on the bottom of the ditch and 12 inches of dirt on top then run the water line. Seems that's backwards but what can I say.

    Thanks to all for your input.
     
  9. kmaproperties

    kmaproperties Well-Known Member

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    CODES by us say buried lines need to be 12 inches apart if in the same trench, so a ditch witch won't work. Its so you can dig them up for repairs and not affect the good lines. It's an overkill cause you don't have to repair lines much anymore with the plastics in use.
     
  10. tiogacounty

    tiogacounty Well-Known Member

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    Hey, as an electrician for the last couple of hundred years, (well some days it seems that long) I'll chime in. At that length, the least you can get away with is a 8/2 UF cable direct buried to at least 24". This will provide plenty of power for a 30 amp 120 volt rv receptacle. Personally, I do not put any wire in the ground unless it's in pvc conduit, but it's you choice and your wallet. Have fun.
     
  11. Chuck

    Chuck Well-Known Member Supporter

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    It amazes me how often I have a question about something and come here to find that someone has just asked the very same thing. Wow.

    Anyway, I'm going to run power out to our gate, so I can put in some small lights and maybe a camera or driveway monitor. It's about 150 feet.

    What size wire would I need for that?
     
  12. rambler

    rambler Well-Known Member Supporter

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    Chuck, I like to play with numbers, so here is a voltage drop calculator:

    http://www.elec-toolbox.com/calculators/voltdrop.htm

    This lets you compare copper vs aluminum, and different amp draws vs what size wire you will need - for the distance you are running. And if you want 120 or 240.

    If all you want is 120v 20 amp out there, looks like #6 copper or #4 Al would be the ticket.

    --->Paul
     
  13. seedspreader

    seedspreader AFKA ZealYouthGuy

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    Let me double or triple reinforce the importance of using an underground conduit. I don't care if you get "direct bury" line or not. For your protection and the next guys, put it in a conduit. We are in the process of tapping into our septic system with an "in-law suite" for my Mom and Dan and as my dad was operating the back hoe he came across the electricty (thankfully inside of conduit) in an unexpected place. He was being careful but still put a little dimple in the conduit. It could have been costly or dangerous had it not been done right.
     
  14. billyj

    billyj Well-Known Member

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    A very valid point, it's time for me to reconsider, although it's not totally permanent.
    Thanks
     
  15. tyusclan

    tyusclan Well-Known Member

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    Chuck, the lights and camera you're talking about have very little amp draw. Number 12 is all you would need for that. You can either run it in PVC conduit or bury 12 w/ground UF. If it's going to be a permanent thing I would put it in conduit. And stick with copper wire. I never run aluminum wire for anything, ever. I hate the stuff.
     
  16. rambler

    rambler Well-Known Member Supporter

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    Fair enough, but when I had my farm rewired last summer, the REA brought in the hi-wire underground. Direct burial. What, 4000, 10,000 volt???? No conduit on that.

    The wires going to the buildings, some as thick as a thumb (just the wire, not counting the insulation) was direct burial al. Seems silly to bother putting down 900 feet of conduit around the 120v wires when they didn't conduit the 700 feet of high-voltage stuff.

    --->Paul
     
  17. joken

    joken Well-Known Member

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  18. The part of the country I live is somewhat rocky. Being a electrician myself I've seen my share of rock eatened underground service wire. Most usually they last right around 10 years and then they have to be replaced. So in my opinion if you aren't going overhead then you would be better off installing pvc pipe. And pvc pipe isn't really that expensive, especially when you compare it to having to get a backhoe and a electrician out to replace the existing underground service.
     
  19. tiogacounty

    tiogacounty Well-Known Member

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    WOW! I read this post and assumed that rambler had made a data entry error to come up with that wire size. Then I went to the link and got the same answer. The only problem is that the thing is completely wrong, and that wire size is about five times bigger than what you need. The issue is clearly stated on the same page as the caculator. It does not use ampacity tables from the code, and consequently is of little value. The starting point of voltage drop caculations is the ampacity design value, as listed in the code tables. For solid # 12 wire in many styles it is 25 amps. This does not mean you can use it for a 25 amp load, it's just an engineering #. The other issue is that you can only load a breaker or fuse to 80% of it's rated value in this case. So it will never exceed 16 amps on a # 12 wire, using the proper 20 amp breaker. Finally the small load proposed by Chuck will, most likely, never get even close to 16 amps. The bottom line here is that # 12 wire will be just fine. A lot of times I fine "weasel clauses" on blueprints indicating that the engineer is leaving the wire size up to the electrician in the field. If the longest distance to a light or receptacle is under 175', I rarely take the time to do voltage drop caculations, and just go with whatever is standard.