Conduit questions

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Wxboy
Wxboy Solar Expert Posts: 70 ✭✭✭✭
in Solar Beginners Corner #1
For the past 9 months the wiring to my panels has been strewn across the yard so I want to finally bury them. I just built a ground based panel mount last weekend and now I need to get conduit for the wires. Slowly getting things in order.

Here are my questions regarding conduit

What is the best kind to use? I am thinking about using roughly 6 foot long plastic sections that fit together.

How deep should the conduit be for practical purposes? Not worried about codes.

How do I figure out what diameter to use or if the wire fits inside is that good enough?

To go from the panels into the ground do I use a vertical piece of conduit with a 90 under ground?

Now for grounding. If I ground everything to one rod near the house how do I get the ground wire from the house and from the panels outside the conduit to the rod? Currently nothing is grounded.
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  • firerescue712
    firerescue712 Solar Expert Posts: 95 ✭✭
    #2
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    Re: Conduit questions

    Schedule 40 PVC conduit for burial. Glue the ends together. Here is a website that shows the conduit fill per size conduit and size wire. http://www.allenelectric.com/referencedata/conduitfill.htm. Your conduit needs to allow free movement of the wiring. There are Conduit 90's that are not sharp turns. You will need to fish the wire through the conduit. About the depth of burying, you had better go by code. Are you planning on upgrading over the years? More wattage means more amps means larger wire...or higher voltage via series wiring of the panels. How far are the panels from the ground source? I am just a neophyte. The seasoned guys will be here soon to be more descriptive of what you need. The biggest thing..always be safe.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #3
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    Re: Conduit questions

    One more thing to add. I have 2 sets of wires from 2 different panels that would go through the conduit, not sure if that is ok. Wire size is 8 awg for one set of wires and 6 awg for the other. I don't plan to upgrade the wire sizes in the future. If the system gets larger and the current increases then I will have to accept the losses.
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  • Rick1
    Rick1 Registered Users Posts: 24 ✭
    #4
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    Re: Conduit questions
    Wxboy wrote: »
    For the past 9 months the wiring to my panels has been strewn across the yard so I want to finally bury them. I just built a ground based panel mount last weekend and now I need to get conduit for the wires. Slowly getting things in order.

    Here are my questions regarding conduit

    What is the best kind to use? I am thinking about using roughly 6 foot long plastic sections that fit together.

    How deep should the conduit be for practical purposes? Not worried about codes.

    How do I figure out what diameter to use or if the wire fits inside is that good enough?

    To go from the panels into the ground do I use a vertical piece of conduit with a 90 under ground?

    Now for grounding. If I ground everything to one rod near the house how do I get the ground wire from the house and from the panels outside the conduit to the rod? Currently nothing is grounded.


    Install an inline exspansion joint to allow for the ground movement during freezing and thawing between the electric box and the underground elbow. Use large radius elbow as a more gradual turning radius will make the wire pull easier.

    When putting the conduit together put pulling lube on the inside of the elbows. After you have the conduit together tie a plastic grocery bag onto a piece of heavy string. Wad the grocery bag into a ball and place it into the conduit. On the other end of the conduit place the hose from a shop vac vacumn cleaner. When you turn on the shop vac the suction will pull the string through the conduit to the shop vac. Tie the string to a heavy rope and pull back the opposite way. Tie all the wires you will be placing into the conduit to the rope and pull. Tie or tape each wire about 6" from each other to make a taper. This will allow the wire to feed around corners much easier. They have a wire pulling lubricant at the hardware store use plenty. Their are u-tube vidieos showing this. I used this method to pull 300 ft. of three 1/0 copper building wire and one #4 building wire.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
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    Re: Conduit questions

    Hi Wx..

    Make the conduit larger than the smallest for the wires that you need for this part of the project to allow for any expnasion later. Some expansion of most systems is almost always needed later -- either more PV or some control funcitons etc.

    And, while you are at it, pull a pull rope into the conduit with the wires, to ease any future expansion. Regarding a ground, you can place a solid bare copper ground wire in the trench with the conduit. This should be about 8, or even 6 Ga for longevity. You can pull a stranded jacketed ground wire inside the conduit.

    PVC Schedule 40 conduit needs to buried deeper than does sch 80, or steel conduit. Believe that Code depth is 18" minimun for Sch 40 PVC. It can be difficult to place a pulling lube in the Ls while keeping it off of the mating surfaces that need a good glueing IMHO. Have had no problems pulling cables in conduit, just placing some lube on the cables as it passes into the conduit. Somewat larger conduit than the minimum does help pulling cables as well.

    BB Bill always councils that addind a second conduit in the trench while you are at it is a good idea, as conduit is relatively inexpensive.

    As noted, Sweeps are large radius Ls which can help pulling, but with the smallish cables that you are pulling, they may not be needed. YMMV, good luck, 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.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #6
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    Re: Conduit questions

    I am cheap--I use black ABS and a pair of 45 degree angles for the "sweeping turns" (if you cannot get the electrical plastic conduit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
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    Re: Conduit questions
    Rick1 wrote: »
    When putting the conduit together put pulling lube on the inside of the elbows. After you have the conduit together tie a plastic grocery bag onto a piece of heavy string. Wad the grocery bag into a ball and place it into the conduit. On the other end of the conduit place the hose from a shop vac vacumn cleaner. When you turn on the shop vac the suction will pull the string through the conduit to the shop vac. Tie the string to a heavy rope and pull back the opposite way. Tie all the wires you will be placing into the conduit to the rope and pull. Tie or tape each wire about 6" from each other to make a taper. This will allow the wire to feed around corners much easier. They have a wire pulling lubricant at the hardware store use plenty. Their are u-tube vidieos showing this. I used this method to pull 300 ft. of three 1/0 copper building wire and one #4 building wire.


    Or just thread the wiring and a pull rope in, in place, section by section, as you glue the conduit sections together. Then drop the whole thing into the trench. Just make sure not to glue the wires to the inside of the conduit. :-)
    SMA SB 3000, old BP panels.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #8
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    Re: Conduit questions
    inetdog wrote: »
    Just make sure not to glue the wires to the inside of the conduit. :-)

    When you glue the conduit together, apply the glue only to the male fitting. If you put glue on the female, the male will push that glue into the interior where it may form a partial obstruction or stick to your wires.

    Also, if you take the wise advice to lay a second conduit in the trench, make sure to run something (rope or nylon twine) through it now. The conduit may fill with water over time and you will not be able to use the shop vac to pull a string through later.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Desert Rat
    Desert Rat Solar Expert Posts: 138 ✭✭✭
    #9
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    Re: Conduit questions
    Wxboy wrote:
    If I ground everything to one rod near the house how do I get the ground wire from the house and from the panels outside the conduit to the rod? Currently nothing is grounded.


    Use bare copper for the ground wire and bury it in the trench alongside the conduit. It will function as one big grounding electrode.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #10
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    Re: Conduit questions

    I am in western Pa. The electrician burryed mine 18 inches. I used 1 1/4 inch conduit for my system. That would be a nice size to use. I think 1 inch would work but the 1 1/4 inch will only cost you a few dollars more. solarvic
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