Is wire color important?

Steve961
Steve961 Solar Expert Posts: 93 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
I've been looking for reasonably priced #10 THHN/THWN wire for the 65 foot run between my panels and the charge controller. There will probably be 2 pairs of this wire inside 3/4" PVC conduit its entire length. I recently found a screaming deal on Craigslist for 400 feet of #10 stranded white THHN/THWN wire for $25. That's close to $0.06 per foot compared to Home Depots price of $0.47 per foot.

Is it required, or even necessary, to have the wire be different colors for positive and negative? I even see that the forum sponsor currently sells their #8 cable with two black leads - http://www.solar-electric.com/8-2-tc.html . Keep in mind that this is for a small, and somewhat remote, off grid cabin.

Thanks.

Steve
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Comments

  • CATraveler
    CATraveler Solar Expert Posts: 98 ✭✭✭✭
    #2
    Re: Is wire color important?

    Buy the wire and buy a roll of red electrical tape from HD for the positive ends.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Is wire color important?

    Black goes with everything. :D

    There are conventions about wire colour and applications but I'm not aware of any actual laws. An inspector might have a different opinion on this.
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  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    #4
    Re: Is wire color important?

    I like the electrical tape idea. I'm also fortunate in that there are no inspectors who care what I'm doing.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #5
    Re: Is wire color important?
    Cariboocoot wrote: »
    Black goes with everything. :D

    There are conventions about wire colour and applications but I'm not aware of any actual laws. An inspector might have a different opinion on this.

    The main NEC (National Electrical Code) has the force of law in terms of building and safety codes where it has been adopted. Its restrictions are that any grounded conductor can be white or gray, but definitely not black or red or blue. The (safety) grounding conductor must be green (with optional stripe) or bare. The standards are there so that someone working on the equipment later has some idea of what is what.
    For that purpose tape or paint is perfectly acceptable as long as it is done at all ends and junction points of the wires involved.
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Is wire color important?

    Except that the OP was asking about DC wiring, hence the "positive" and "negative" in his post.
    Whereas the NEC does have certain regs about DC, they seem to have been invented by someone with a decided lack of familiarity with direct current. :roll:
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #7
    Re: Is wire color important?
    Cariboocoot wrote: »
    Except that the OP was asking about DC wiring, hence the "positive" and "negative" in his post.
    Whereas the NEC does have certain regs about DC, they seem to have been invented by someone with a decided lack of familiarity with direct current. :roll:

    NEC uses similar color codings for DC as it does for AC. It's not the same as everyone is used to in low voltage work (i.e. red for + and black for -) but at least it's self consistent within the framework of the NEC.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Is wire color important?
    bill von novak wrote: »
    NEC uses similar color codings for DC as it does for AC. It's not the same as everyone is used to in low voltage work (i.e. red for + and black for -) but at least it's self consistent within the framework of the NEC.

    Ah, you mean like with 240 VAC where one hot wire is black and the other hot wire is red? ;)
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  • SolaRevolution
    SolaRevolution Solar Expert Posts: 410 ✭✭
    #9
    Re: Is wire color important?
    bill von novak wrote: »
    NEC uses similar color codings for DC as it does for AC.

    The NEC makes no distinction between the DC + or - on the matter of color. It only requires that the neutral (grounded conductor) be identified.

    If your DC system is negative grounded your negative "shall" be "identified" as a neutral. If your DC system is positive grounded your positive shall be identified as a neutral. If your system is floating and does not have a ground bond for either the + or - then neither is allowed to be white, gray or otherwise "identified" as a neutral. There is no requirement that an ungrounded + or - be any particular color as long as it is not white, gray or green.

    NEC 200.6(A): ..."An insulated grounded conductor of 6 AWG or smaller shall be identified by a continuous white or gray outer finish or by three continuous white stripes on other than green insulation along its entire length"...


    (Note that there is an exception which allows marking of black insulation for USE2/RHH wire when used for module output and interconnect wiring)

    -Alex Aragon
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #10
    Re: Is wire color important?

    Codes are different , But also similar for most areas.
    Tape MUST be within "real close " to the end of wire/ connection , and then if that wire/cable is within a gutter or box , it must be spiral "barber pole" wrapped to ID in the box/gutter. Colour / color for different country's / voltages / but most are Green / green-yellow are grounds . But for the question of jacket / insulation colour , it must always be marked and easily ID'ed.
    Small wire 0-16 , strip end, pole spiral and then wrap the end where the striped jacket is, I always leave a bit exposed so the next or me always gets to see that the black wire is considered a blue (in 3 phase) .. SO always mark with the correct colours & label voltages if needed . This is for independent wires/wires in a conduit. Check the local code books , there you will find colours used. DC powers have different colours also between country's. Red is always power as Ive seen all over in DC.

    Best to always mark .
    VT
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #11
    Re: Is wire color important?
    Cariboocoot wrote: »
    Ah, you mean like with 240 VAC where one hot wire is black and the other hot wire is red? ;)

    Correct. That seems wrong to people who are used to low voltage DC. But within the NEC it is consistent; black is always hot.
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  • petertearai
    petertearai Solar Expert Posts: 471 ✭✭✭✭
    #12
    Re: Is wire color important?

    I would get some shrink sleeve, this will provide a longer lasting identification of the cable colour.
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #13
    Re: Is wire color important?
    Cariboocoot wrote: »
    Ah, you mean like with 240 VAC where one hot wire is black and the other hot wire is red? ;)
    That's not mandated by the NEC, although local jurisdictions may require it.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #14
    Re: Is wire color important?

    Hey guys; have any of you noticed how one of your legs is getting longer than the other? :p
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #15
    Re: Is wire color important?
    Cariboocoot wrote: »
    Hey guys; have any of you noticed how one of your legs is getting longer than the other? :p

    yikes. i had a million things to say about this, but none i can say here.:p
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