Solar panel wiring in attic

Steve961
Steve961 Solar Expert Posts: 93 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Can I safely run the wiring from my solar panels to my charge controller through the attic using just 2 Conductor Stranded Outdoor Tray Cable? This is a small off grid cabin with a 200 watt array, and I'd like to avoid the hassle of installing metallic conduit if at all possible.

Thanks.

Steve
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #2
    Re: Solar panel wiring in attic
    Steve961 wrote: »
    Can I safely run the wiring from my solar panels to my charge controller through the attic using just 2 Conductor Stranded Outdoor Tray Cable? This is a small off grid cabin with a 200 watt array, and I'd like to avoid the hassle of installing metallic conduit if at all possible.

    I would do so ...;-)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Solar panel wiring in attic

    If this is unused (unfinished) attic space it should be okay. Code varies from place to place and some inspectors have fits about "exposed wiring inside living space".
    Electrically, as long as it is sized sufficiently to handle the current without a lot of V-drop it will work. One caution; due to the nature of attic spaces being very hot some times don't try to run it "near the limit" of current as the ability to dissipate plays a major role in Ampacity and this will be affected by high ambient temps. (Same as in conduit, really.)

    (Waits for someone to come along and disagree.) :roll:
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #4
    Re: Solar panel wiring in attic
    unicornio wrote: »
    I would do so ...;-)

    No disagreement here...

    As long as the cable is placed where it is safe from mechanical attack (being stepped on or tripped over, having nails or screws driven through it, etc.) there is not a problem. (Plastic pipe or conduit can help in this respect, but will increase the wire temperature!)
    If you think that someone else will ever be working in your attic, label it as externally supplied power so that nobody tries to mess with it thinking it is safe because the Mains disconnect is off.
    Just common sense precautions, nothing special required.
    SMA SB 3000, old BP panels.
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  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    #5
    Re: Solar panel wiring in attic

    The attic is unfinished/uninhabited and well ventilated. I plan on running it through lag eye screws underneath the 4"x8" rafters. Sounds like I'm good to go.

    Thanks guys.
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #6
    Re: Solar panel wiring in attic

    Code says that if it is less than 50V, you can do just about anything you want.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Solar panel wiring in attic
    solarix wrote: »
    Code says that if it is less than 50V, you can do just about anything you want.

    Ah, but is it less than 50 Volts?
    An array could be almost any Voltage.

    I'm not keen on the idea of running it through eyebolts. Should be fastened securely to whatever is supporting it.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #8
    Re: Solar panel wiring in attic
    Cariboocoot wrote: »
    Ah, but is it less than 50 Volts?
    An array could be almost any Voltage.

    I'm not keen on the idea of running it through eyebolts....

    Among other things, using eye-screws would require pulling back the whole length of wire to relocate the attachment point. If you would really use eyebolts and the nut could be backed off without requiring the eyebolt to be turned, then it should be OK on those grounds.
    SMA SB 3000, old BP panels.
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  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    #9
    Re: Solar panel wiring in attic

    Good point about the eye screws, I'll just use some of the appropriate wire staples I have laying around. In regards to voltage, these are 12 volt panels to be run in parallel.

    Thanks for the advice.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Solar panel wiring in attic

    A million years ago when TV came through the air and you needed this weird device called an antenna to receive it, back before the age of coaxial cable, we use this flat two stranded wire called "300 Ohm FM". It had these stand-offs that screwed into wood (some were bolt-end) with eye loops. The loops were fitted with plastic insulators that had a slit to slip the wire into and then you pushed it into the loop.

    There were only three TV networks in the U.S.A. then. :p
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #11
    Re: Solar panel wiring in attic
    Cariboocoot wrote: »
    ... back before the age of coaxial cable, we use this flat two stranded wire called "300 Ohm FM".
    There were only three TV networks in the U.S.A. then. :p

    Ah, twin-lead! Hams still use it occasionally because it has a lower attenuation value than the best coax and in some cases can handle higher power at lower cost. (Provided you keep it away from metal surfaces, sigh.) And it is still the easiest way to build a folded-dipole FM antenna.
    SMA SB 3000, old BP panels.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #12
    Re: Solar panel wiring in attic

    marc,
    do you mean one of these as they still exist?
    http://www.radioshack.com/product/index.jsp?productId=2104003

    inetdog,
    yes, hams do still use it and i took it one step further and built some 30+ feet of it, but i made it heavy duty with a 6in spread and #10 wire. for the nonhams out there we call twin lead ladderline. are you licensed?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Solar panel wiring in attic

    Yes, Niel; that's what I meant.
    I remember they had ones with strap too for going on poles. You had to get them aerials up there, you know; to DX those far away places! :D
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #14
    Re: Solar panel wiring in attic
    niel wrote: »
    are you licensed?
    Never got around to it. Not even Tech, although I have gone to a few Field Days with ham friends. (I am a card-carrying procrastinator.)
    SMA SB 3000, old BP panels.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #15
    Re: Solar panel wiring in attic
    inetdog wrote: »
    Never got around to it. Not even Tech, although I have gone to a few Field Days with ham friends. (I am a card-carrying procrastinator.)
    I am so impressed!! Really. I always wanted to be a procrastinator, but I just never got around to it. --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #16
    Re: Solar panel wiring in attic
    vtmaps wrote: »
    I am so impressed!! Really. I always wanted to be a procrastinator, but I just never got around to it. --vtMaps

    Early in the 1970s, the Procrastinator's Society of America picketed the White House with signs reading "President Madison, this is YOUR war!" (1812).
    That inspired me to join the group. Someday.
    SMA SB 3000, old BP panels.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #17
    Re: Solar panel wiring in attic

    i wonder if the members of the procrastinators society are late for their own funerals or does membership stop at death?:-):p
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