Conduit size for 4 #6 thhn conductors

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Old 10-08-20, 04:23 AM
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Conduit size for 4 #6 thhn conductors

Hello,

I'm running underground conduit with 4 lines of #6 copper THHN for about 100' with a couple 90 degree bends. I dont do this very often, so I'm wanting to make sure I get a big enough conduit for an easy pull. From online fill calculators, they say I could use 1", but I'd rather go a little bigger to make my life easier. Would 1.5" be plenty, or should I go to 2"? Looking for someone with experience that knows what would work best.

Thanks in advance for any thoughts!
 
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Old 10-08-20, 10:23 AM
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It's always better going with a larger size but 2" would be excessive.
1-1/2" should be more than large enough for an easy pull.

If your wiring is new..... it's more than likely THHN/THWN.
If it's older wiring it may be THHN only and not rated for wet locations.
 
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Old 10-08-20, 01:15 PM
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Thank you PJmax for the advice. I was thinking 2" might be overcooking it but appreciate your confirmation.

The wire spool I bought is new, and I'm pretty sure it's dual rated THHN/THWN.
 
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Old 10-08-20, 01:44 PM
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3/4" Sch40 PVC conduit is code compliant for four #6Cu THHN/THWN, so 1" is plenty big. To use 1.5" is a waste unless you plan on increasing the conductor size in the future.
 
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Old 10-08-20, 07:42 PM
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Why do you need 4 #6 wires? At the most, you only need 3 - #6 and one #10 (or #8 of over 60 amps) for the ground wire.
 
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Old 10-11-20, 05:51 PM
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All,

I ended up going with 1.5" conduit, and that was decided by the inventory at the local hardware store with what they had in stock. I bought a roll of #6 that was 500', and just figured I would use 4 legs of the same wire, just because I don't have or didn't buy the separate ground wire.
 
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Old 10-11-20, 07:23 PM
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I assume you got a roll of black. To be code compliant the neutral needs to be white and ground green. You are not to re-color #6 and smaller conductors.
 
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Old 10-13-20, 11:53 AM
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@ pattenp: Code Smode what ciser123 is proposing is perfectly safe and will work fine although I would get paint or something other then colored tape (which can fall off) to identify each #6 conductor on each end of the conduit run.


 
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Old 10-13-20, 12:49 PM
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CircuitBreaker, where did I say it was not safe? I said it was not code compliant to re-color conductors #6 and smaller.
 

Last edited by pattenp; 10-13-20 at 02:18 PM.
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Old 10-13-20, 01:34 PM
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The 'bay has acdcwiresupply. I've bought 125' of BK, WH, RD in 6 awg with 125' 10 awg in GN. Good quality republic wire.
 
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Old 10-13-20, 02:38 PM
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@ pattenp I did not say you said it was unsafe the code is not always 100% about what works and what does not work. buying one large spool of conductor is a great way to save money if if not 100% code compliant but it can be painted or other wise made to be easily distinguished from the others you only need to color three of the four wires (RED/Black/White/Green)
The good and bad thing about electricity is it almost always works even if the wiring is not 100% safe.

I used to live in an old 1880's farm house in my younger years the only wiring to my bedroom looked to be 18AWG x 2 parallel SPT-1 (lamp cord) that was stapled to the wall it worked for my lamps and *YIKES* the occasional 1500W space heater (that wire also did a good job as a space heater then).

I lived in that place until I was 13 years old it still stands today albeit modern wiring.

 
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Old 10-13-20, 07:09 PM
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I used to live in an old 1880's farm house in my younger years the only wiring to my bedroom looked to be 18AWG x 2 parallel SPT-1 (lamp cord) that was stapled to the wall it worked for my lamps and *YIKES* the occasional 1500W space heater (that wire also did a good job as a space heater then).
So you are saying that this is OK since it works?

Sorry but Pattenp is correct. Re-identifying conductors smaller than #4 is not NEC compliant. The code is not designed to save you money, it is put in place so that everybody follows the same safe practices installing electrical systems. The supply house that we buy material from (which also sells to the public) will charge the same price whether you buy a 500' roll or 5 cuts of 100'
 
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Old 10-13-20, 07:32 PM
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No sorry I was trying to say that is the problem with electricity even if the installation is 100% unsafe like my 18AWG x 2 SPT-1 stapled to the walls it will almost always work (as in provide power to my 1,500W space heater).
 
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