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Thread: Aluminum wire and plastic conduit or copper and metal?

  1. #16
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by hj View Post
    If you are resigned to using the 60 amp breakers, why would you stay with the 100 amp wires, given the additional cost for the larger conductors?
    Partly because I got the wire at a good price, but also because I would rather run heavier wire than is actually required anyway.

  2. #17
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by mattbee24 View Post
    From what I understand, the sub panel is in an attatched building, and he is running emt along the wall all the way to the sub panel. He is using #4 copper to feed the sub panel. Around here, #4 copper is acceptable for 100a service in a residential home, and #3 for commercial. (he is using a 60a breaker so that point is mute anyway)

    As far as using the conduit as the ground, I didn't think you could do that, but I could be wrong.

    If he does need to pull a ground, it looks like he should still be able to do that. The chart I have shows you can have up to 4 strands of #4 thhn in 1" emt.

    That's just my opinion, I could be wrong.
    You definitely have the details of my structure and purchased-so-far supplies correct, and I am not yet absolutely certain about the EMT as the ground ... and if four strands of #4 actually do turn out to be too much for the 1" EMT, I believe I can use a smaller ground wire. The aluminum wire I had merely *thought* about using has a #4 ground running alongside three strands of #2. So, I can imagine #6 copper would be fine as a ground alongside #4 copper lines and a neutral if I must have a fourth wire even with continuous EMT.

  3. #18
    Engineer Furd's Avatar
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    I am not yet absolutely certain...

    I believe...

    I can imagine...
    The electrical codes are not items of uncertainty, belief or imagination. They are hard and fast rules and where enacted into law they MUST be followed. There is no place for uncertainty, belief or imagination. Follow the codes or do not do the job.

  4. #19

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    Even if you are not yet required to pull a ground, pull a #8 anyway.

    Grounding = good.

    The charts may say you can fit the wires in but the charts are often unrealistic. Does it still say something like 10 #12's in 1/2 EMT???

    I recently re pulled 3, 4's + ground into an existing 1" EMT and it was NOT easy. An inexperienced person couldn't have done it without damaging the wire. Wires cannot twist or kink at ALL or they take up too much space.

    Run 1.25 or 1.5.


    There is no place for uncertainty, belief or imagination.
    But there are MANY places for interpretation.
    Last edited by 220/221; 10-31-2008 at 05:35 PM.

  5. #20
    Electrical Contractor/Instructor jwelectric's Avatar
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    Anyone want to bet that this is what he is installing?

    click here

  6. #21
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by Furd View Post
    The electrical codes are not items of uncertainty, belief or imagination ...
    I understand, and I do not proceed until my own uncertainties and unknowns have been resolved.

    Quote Originally Posted by 220/221 View Post
    Even if you are not yet required to pull a ground, pull a #8 anyway.

    Grounding = good.
    That makes sense to me, and I might just do that. Thank you.

    Quote Originally Posted by 220/221 View Post
    I recently re pulled 3, 4's + ground into an existing 1" EMT and it was NOT easy. An inexperienced person couldn't have done it without damaging the wire. Wires cannot twist or kink at ALL or they take up too much space.

    Run 1.25 or 1.5.
    I have yet to put the wire and EMT side-by-side, but I will take a good look and do the computations before hanging anything. I only have to go about 20' before my first turn, then another 20' before turning again and then turning up to the subpanel, and I can put that last turn in place after-the-fact, if necessary. Also, this is not my first time pulling wire.

    Quote Originally Posted by jwelectric View Post
    Anyone want to bet that this is what he is installing?

    click here
    No, that stuff was #6, and I have #4.

    I greatly appreciate everyone's help here, and I especially thank you, Jar546, for responding to this thread at all after others had either ignored or missed it entirely. I would have preferred to just ask simple questions and get straight answers -- Aluminum and plastic or copper and metal? -- but even antagonists can end up being helpful.

    Peace.

  7. #22

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    I have yet to put the wire and EMT side-by-side, but I will take a good look and do the computations before hanging anything. I only have to go about 20' before my first turn, then another 20' before turning again and then turning up to the subpanel, and I can put that last turn in place after-the-fact, if necessary. Also, this is not my first time pulling wire.
    Still need some clarification for grounding purposes and for all purposes for that matter:

    1) What code cycle are you under?

    2) Is the garage attached or detached (conflicting posts)?

    3) Will the conduit be run underground or above ground?

    4) Will the conduit if run above ground be subject to the weather?

    5) Are your pull points from beginning and the end only or do you have pull points in between start and finish too (real pull points)?

    6) Will the installation get inspected by local authorities during or at completion?


    If the job is not going to be inspected then I refuse to assist you with anything further.

    Without ALL of those questions answered above, no one can really help you or give you guidance.

    Either you want help and realistic, actual guidance or you want people to tell you what you want to hear regardless of the actual situation.

    Safety first. People have died doing what your are plannin on doing.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  8. #23
    Moderator & Master Plumber hj's Avatar
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    1. originally you were debating aluminum or copper, but the aluminum would have required a larger breaker.
    2. Originally you were debating 1" or 1 1/4" conduit.
    3. Then you debated whether the copper wire would support 100 amps, which is the same breaker you would have needed for the aluminum wire.
    4. Now you are sticking with the 60 amp breaker which does not need the same wire as the 100 amp one would have.
    5. Now you say you have the 100 amp wire and the conduit, so why are we still discussing it.
    6. Since there is little possibility that you will ever reach the 240 v, 60 amp plateau, why worry about oversizing the wire?

  9. #24
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by hj View Post
    1. originally you were debating aluminum or copper, but the aluminum would have required a larger breaker.
    Yes, I believe my 60-amp breaker would not have accepted #2 wire.

    Quote Originally Posted by hj View Post
    2. Originally you were debating 1" or 1 1/4" conduit.
    Yes, I was wondering what size conduit I would need after deciding about the wire.

    Quote Originally Posted by hj View Post
    3. Then you debated whether the copper wire would support 100 amps, which is the same breaker you would have needed for the aluminum wire.
    Yes, and when I discovered I could not afford 100-amp copper, I settled for the #4 that will easily carry all the current my existing 60-amp breaker will allow through.

    Quote Originally Posted by hj View Post
    4. Now you are sticking with the 60 amp breaker which does not need the same wire as the 100 amp one would have.
    Yes.

    Quote Originally Posted by hj View Post
    5. Now you say you have the 100 amp wire and the conduit, so why are we still discussing it.
    Other than for the sake of some folk's desire to trash me or whatever, I have absolutely no idea! My questions have all been answered:

    Three strands of #4 copper inside 1" EMT as a ground will easily carry 60 amps for 50' to my attached workshop's subpanel and be completely legal here where I happen to live.

    Quote Originally Posted by hj View Post
    6. Since there is little possibility that you will ever reach the 240 v, 60 amp plateau, why worry about oversizing the wire?
    I was not actually worrying about that, but at least now I know the wire is quite sufficient.

  10. #25
    DIY Junior Member peteferrell's Avatar
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    Dear Sir,
    I am a licensed Master Electrician. Funny you are asking this question as I am currently adding a 100 ampere sub-box in my own workshop which is also about 50 feet from my main box. I already had some 2 gauge alum. twisted duplex wire taken down from a power drop. First let me say that if you can afford the copper wire, then that is your best bet. Second, if you can't afford the copper wire in your project budget, then the alum. wire is fine. Just keep in mind the alum. wire does not conduct as well as the copper so we must treat it differently. Since I already have the #2 alum. I'm going to use it myself. When using alum. wire you must remember it will emit more heat at full load than the copper. There fore up size your non-metallic conduit (PVC) on size to allow more room for the wire to "breath." I choose to use 1 1/2 PVC conduit. The number of turns doesn't matter as long as you have wire pull access along the way. Never put more than 270 degrees of turns under a floor or underground as you will not be able to pull wire through it. #2 Alum. is rated at 124 amps of current in a raceway or conduit. When I design and build anything electrical, I always try to design the equipment to never run at more than 80% full load on the amp rating of the materials. In other words, if the wire is rated at 124 amps, then a 100 amp breaker feeding the wire is perfect. Be sure to drive an 8 foot copper ground rod at the new sub-box. You only bond the neutral and ground at the main box. All sub boxes should have the neutral and ground buss bars separate from one another. Just remember the main job of the breakers is to protect the wire and equipment down stream from being over loaded which could cause fire. Never use a larger breaker than the wire or equipment it is feeding is rated at. Even better, don't exceed the 80% load factor and you will never have problems kicking breakers. Also when using alum. wire don't forget the Anti-ox grease in the wire connection points. Alum. expands more than copper when it heats up, the grease will help insure a good non-oxidized connection. I hope this helps!

  11. #26
    Moderator & Master Plumber hj's Avatar
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    quote; #2 Alum. is rated at 124 amps of current in a raceway or conduit.

    My book says 3 #2 alum in a conduit is limited to 75 amps.
    Licensed residential and commercial plumber

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