Long Electrical Run - 15 amp or 20 amp outlet

Discussion in 'Homesteading Questions' started by canfossi, Mar 4, 2011.

  1. canfossi

    canfossi Well-Known Member

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    I am going to be installing a post light this spring and was at the hardware store today to get a GFCI outlet, they come in 15 amp and 20 amp, which one should I get for this? I am going to be putting a GFCI outlet on the lightpost so that it can use it when the lamp is on. There is going to be only one post lamp about 160 feet from the fuse box. Also, someone suggested using 12/2 wire instead of 14/2 due to line loss. Any tips or advice would be greatly appreciated. Thanks Chris
     
    Last edited: Mar 4, 2011
  2. Batt

    Batt In Remembrance Supporter

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    Keep it less than 300 ft. from the transformer and the line loss should be minimal. 15 amp, 14/2 would work, 20 amp requires 12/2. Probably best to use 12/2 anyway just to give you a margin.
     

  3. switchman62

    switchman62 Well-Known Member

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    I would go with the 12/2 wire for sure over that distance. here is a link to a voltage drop calculator. You can put in your figures and see the V drop. I believe they say you should not have more than a 5% drop on full load.

    http://www.nooutage.com/vdrop.htm
     
  4. canfossi

    canfossi Well-Known Member

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    Okay thanks! So I will be fine using the 12/2 all the way from the fusebox to the receptacle and then to the lamp? I'm assuming I'll need a 20 amp fuse for this? Thanks Chris
     
  5. rambler

    rambler Well-Known Member Supporter

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    Here is a simple voltage drop calculator I like, it is rather conservative at 3% drop so it suggests big wires, BUT then you already have some drop in the rest of the wires in your system, and electric motors really are much happier if you keep it to a 3% drop.

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

    I would not even cosider a 14 gauge wire. For a 20 amp, you _must_ use 12 gauge to start with, 14 gauge doesn't handle a 20 amp fuse at all.

    A 12 gauge wire is typically good for 15 amp at 100 feet.

    For your 160 feet, they suggest a 6 gauge. Even at 5% drop, you can't get there for less than a 10 gauge wire and be remotely good.

    You want a light and an outlet, you really should plan for a 20 amp circut.

    I can't imagine going less than a 10 gauge wire, even that is a little light but you are gonna be too light with a 12 gauge. A 6 or an 8 would be even better.

    Most of the cost & work is in putting in the trench and doing the work, might as well do it right the first time & save some money? Someday you want to plug in an engine heater or a 1hp motor out there, & when the breaker trips or worse something melts down, then you get to redo it all over again.

    If it were me I'd do a 20 amp with 6 gauge wire. I can understand trying to skimp by, and a 15 amp with 8 or maybe 10 gauge would work, but you'll be disappointed some day.

    There are times to scrimp and save, but electrical costs a lot of time & money to do the work. Nice to get it right the first time & not worry about burning something down.

    Just my opinion. :)

    --->Paul
     
  6. rambler

    rambler Well-Known Member Supporter

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    While rules are based on safety and are similar; you are in Canada so check your local requirements. Most of us from the 'States might be thinking USA requirements. :)

    Do you really have fuses, or do you have breakers?

    I'm going to assume Canada reqires a full ground as well, so you will have a cable with 3 wires in it - hot, neutral, and ground.

    Do you know how to bond all of those properly, and get a good working system that is safe? It's easy to make electricity work, can be done with one wire actually; but it takes some thought & rule following to make it _safe_ for you & for kids and for the next owner of the property.

    Wonder if you could find an electrician to do the final work for you, you can get everything ready, trench and all, he just gets the wires hooked up & proper?

    --->Paul
     
  7. Nevada

    Nevada Voice of Reason Supporter

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    The 15 amp service should be fine for a post lamp.

    I don't think 12 gauge wire is going to work for you if you want to support a full 15 amps though. For 15 amps you'll need more like 6 gauge, which will be pricey. Consult this table to see what I mean.

    [​IMG]

    You might consider getting a lighter fuse/breaker for the job for economical reasons (that much 6 gauge wire is really going to cost you). For example, if your lamp will draw no more than 5 amps (600 watts), and you fuse the line for 5 amps, then you can get away with 12 gauge wire. If you fuse it for 2 amps (240 watts) then 14 gauge will be fine.

    Also consider that it may cost a lot less to drive a ground rod at the light post rather than run a ground wire all the way back to the load center. But since you are looking to use GFCI many jurisdictions aren't going to require an equipment ground at all.
     
  8. rambler

    rambler Well-Known Member Supporter

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    In the USA, that very rarely is acceptable any more. As of about 2006 or so??? They now want a full isolated ground wire almost all the time, even between buildings on the same place. One can find a farm exception, but it's not prefered any more and many local inspectors won't allow it.

    I don't know about Canada rules on that, and I agree it can work & is normally reasonably safe. Just saying, the rules have changed in many locations if one is worried about resale or insureance coverage, etc. Good advice otherwise tho.

    I had the whole farm service wires redone in 2007 or 8 right before the new rules took effect, saved some money by going with the old rules, smart of me right? Now I added a building last year, and it was very difficult to get it wired up, there was a lot of talk of needing to run a new set of 4 wires from the main transformer 650 feet away, instead of just adding on to the 3 wire box on a building 100 feet away. And we are talking wires that are well beyond using the gauge numbering system, the metal is about as thick as a thumb in each of the 3 (or 4) wires. So my 'savings' back then almost cost me a bundle last year, but it eventually was ok to go with the cheaper route. So anyhow, my advise on wiring tends to point out the better options for future needs, I don't mean to spend other people's money needlessly. :)

    --->Paul
     
  9. cast iron

    cast iron Well-Known Member

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    Good advice here, pay me now or pay me later. I used 12ga direct burial, 20amp receptacles, on a 20 amp circuit for an outdoor run to various points in the backyard thinking I would only have a grill rotisserie plugged in and maybe some garden lighting.

    Next thing you know we had two ponds with fancy waterfalls and the related water pump and lights. Pretty soon there was an electric smoker plugged in next to the rotisserie, a bird bath heater, and the laptops get plugged into those outlets when we are sitting on the deck drinking and posting. The circuit has held so far, as long as we don't do all of the above at the same time, and as long as we keep the pond pump filters clean, but I'd feel better about it if I had gone just a little bigger.
     
  10. edjewcollins

    edjewcollins Well-Known Member

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  11. edjewcollins

    edjewcollins Well-Known Member

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    let me clarify, 12/2 and a 20 amp receptacle, but use a 15 amp breaker. If you use 12 gauge wire on a 15 amp breaker, voltage drop at the receptacle will be 9.2 volts for an available voltage of 110.8 volts. If you use 14/2 wire, voltage drop increases to 14.6 for an available voltage of 105.4. This is based on a 160' circuit. here is the voltage drop calculator I used:

    http://www.csgnetwork.com/voltagedropcalc.html
     
  12. Oldcountryboy

    Oldcountryboy Well-Known Member Supporter

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    canfossi, just what are you going to be using the outlet for? Electric weedeater, christmas lights, or something else?

    What your going to be using out there along with the light pole can make a difference of just how much voltage drop you can get away with? If the outlet is for Christmas lights then you might could get away with just running #12 conductors as Christmas lights will only pull a couple of amps along with maybe 1 amp draw on your light pole. But if your going to be running something that draws more amps such as a weedeater, then you might want to step up the guage of wire.
     
  13. VaFarmer

    VaFarmer Well-Known Member

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    First thing is identify your use. (draw), couple lights, weed eater, trk blk heater, 12G will be OK. If more stuff or eletric motors match your wire & breaker to the demand.
    2nd, 15A GFCI will be fine out on the post. (unless your use demands a bigger wire than up grade the GFCI to match use. Consider a 20A GFCI breaker at the box (or sub panel box) to protect the whole circuit.
    3; use exterior rated wire ( and yea solid copper) (aluminum cable gets into a different set of guidelines) run ground wire (3 pole wiring).
    4; this is bigger issue than any 1 has addressed: you stated fuse box, ( Gee hope you really meant breaker) Fuse is fine as long as you respect it's limits. The biggest mistake that I see home owners do is multiply wires installed under the screw for that fuses output, (circuit tap). The lack of space is the biggest bugboo with a fuse box, the 2nd bugaboo is what homeowners do to there box.Other than that there fine, just outdated. The screw conector is designed for single wire hook up ONLY. Two wires can lead to 1 being loose and create an arching or overheating that Could get hot enough to melt insulation on wire, or ignite something. Circuit breakers are also intented for single wire hook up,(except certain SQ D's). But breaker boxes have more room to hook up new breakers or add split breakers. If you have fusebox look into a sub panel box if needed to add wiring. :sing: Wiring is not complicated but respect the whole circuit from start to finish, just don't run wire with a post & outlet on the end.:bash: Have a good day, mate. :eek:
     
  14. canfossi

    canfossi Well-Known Member

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    I am just using the outlet for plugging in the vaccum to clean the car in winter. Can't get up the hill with the car in winter. Sounds like I should get my electrician friend to help me here. He was a certified electrician. Thanks Chris
     
  15. rambler

    rambler Well-Known Member Supporter

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    Ah - start with the big power consumers right away! :) A good shop vac can pull a lot of amps. I trhink you'll be happy with more than 12 gauge anyhow.

    --->Paul