What cable to use between panels and disconnect

Options
Mike16W
Mike16W Registered Users Posts: 9 ✭
in General Solar Power Topics #1
I am installing my first PV system on my house and I will need to run 4 cables (10ga.), 120/240 single phase, between my junction box on the roof to the disconnect on the side of the house. I will need to run these cables 100ft though a conduit. Does anyone have a recommendation on what cable to use and where to get it for the best price. I understand I will need to use 10 AWG RHW-2 cable. Is this available on line and it would be great if each strand was color coded.
Thanks for any help.
· Share on Twitter

Comments

  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #2
    Options
    Re: What cable to use between panels and disconnect
    Mike16W wrote: »
    I am installing my first PV system on my house and I will need to run 4 cables (10ga.), 120/240 single phase, between my junction box on the roof to the disconnect on the side of the house. I will need to run these cables 100ft though a conduit. Does anyone have a recommendation on what cable to use and where to get it for the best price. I understand I will need to use 10 AWG RHW-2 cable. Is this available on line and it would be great if each strand was color coded.
    Thanks for any help.
    Microinverters?

    I'm pretty sure you can use THWN-2 for that run.
    · Share on Twitter
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3
    Options
    Re: What cable to use between panels and disconnect

    Mike,

    The host of this site carries several appropriate cables for PV wiring, exposed to the elements. One it Tray Cable, this one is 10 GA two conductor:

    http://www.solar-electric.com/10-2-tc.html

    Personally, have never used TC for this application, and prefer individual conductor, such as these:
    http://www.solar-electric.com/incaforsoelp.html

    I am ASUMING that you are in need of PV DC wiring from the panels to the combiner. Altho, the reference to 120/240 AC may change the above.

    If there are junciton boxes on the panels, then you could run conduit from the panels to the combiner, and use Building Wire, THWN/THWN-2 (IIRC). Most building wire has this rating as well as THHN etc.

    If you could be more specific about your need, it would allow better replies to your question.
    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #4
    Options
    Re: What cable to use between panels and disconnect
    Vic wrote: »

    I am ASUMING that you are in need of PV DC wiring from the panels to the combiner. Altho, the reference to 120/240 AC may change the above.
    That's what prompted me to ask if he had microinverters. He wouldn't want to run PV wire 100' through conduit to a disco in any case, though. If it's a DC run without combining, I'd advise transitioning from PV wire to THWN-2 in a J box at the array.
    · Share on Twitter
  • Mike16W
    Mike16W Registered Users Posts: 9 ✭
    #5
    Options
    Re: What cable to use between panels and disconnect

    Yes, I will be using Emphase Micro-Inverters. Sorry, I should of stated that in my post.
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #6
    Options
    Re: What cable to use between panels and disconnect
    Mike16W wrote: »
    Yes, I will be using Emphase Micro-Inverters. Sorry, I should of stated that in my post.
    Use THWN-2 sized appropriately for the summed current from your U-inverters from your AC J box to the panel. I don't think (though verify with your AHJ) that you need a disco between the inverters and your service panel. You should be able to connect directly to a backfed breaker, adhering to the 20% rule, of course.
    · Share on Twitter
  • Mike16W
    Mike16W Registered Users Posts: 9 ✭
    #7
    Options
    Re: What cable to use between panels and disconnect

    Thanks for the information about the wire needed. I checked and I need a disconnect next to my meter in order to meet code in New Mexico.
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #8
    Options
    Re: What cable to use between panels and disconnect
    Mike16W wrote: »
    Thanks for the information about the wire needed. I checked and I need a disconnect next to my meter in order to meet code in New Mexico.

    Um, yes, of course you do. Visible, accessible, and lockable. I don't know what I was thinking when I said that I didn't think you needed one. My bad.
    · Share on Twitter
  • Mike16W
    Mike16W Registered Users Posts: 9 ✭
    #9
    Options
    Re: What cable to use between panels and disconnect

    Thanks. I will use the THWN-2 wire you suggested. I imagine getting them in the different colors makes it easier to sort out and connect. Do you get your wires locally or on the web? Always looking for a good price.
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #10
    Options
    Re: What cable to use between panels and disconnect
    Mike16W wrote: »
    Thanks. I will use the THWN-2 wire you suggested. I imagine getting them in the different colors makes it easier to sort out and connect. Do you get your wires locally or on the web? Always looking for a good price.
    Check your local code for wire color requirements. NEC says white or gray for neutral and anything else besides green for L1 and L2, but in some places you are directed to use specific colors. Here in Austin, for example L1 is red and L2 is black. Ground is green, of course.

    You could have both hot wires the same color, though, if your AHJ doesn't specify. It doesn't matter which one is which from the inverters. Make sure you figure the ampacity and temperature deratings and don't use wire that is too small.

    It's not likely you'll find a significantly better price than at a local electrical supply house for such a small quantity of wire, and they will often sell you just what you'll need instead of a full spool.
    · Share on Twitter

Categories