6/3 romex used to feed a 70amp pool sub panel outside?

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The problem is the nmb

if the wires rated for 90 degrees. I have put in splices before so I can use the 90 degree coulmb and the. Transition to a larger wire to the breaker
 
Jraef said:
NM cable is NOT listed for use in WET locations, period, end of story. So once it goes outdoors you have to transition to something like UF, USE or individual conductors in conduit. Sounds like they opted for the latter. But even #6 individual THHN conductors in conduit is not good for 70A, so that was a mistake (or the "70A panel" statement is not correct and the actual load or MCA is 60A).

The #6 NM on the INSIDE is still only rated for 55A, so if the load or MCA is 60A or more, this smells of a DIY or Handyman project where someone used the 90C column, not knowing the rules.
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#6THHN is also not listed in a wet location unless it is dual rated THHN/THWN
 
An interesting find in online forums for pools and hot tubs and handyman is the recommendation that use of 6/3 and 70A is rampant with no pushback against it's use. Only one reference that mentioned a load calculation or derating but not being used. No mention related to 60deg rating of the NM, just suggested that rating of #6 to 75A. One reference to NEC but misquoted to suggest use of 6/3 at 75A.
 
As I recall, the default temperature value for unmarked terminations100A and above is 75C, but the default value for smaller terminations is 60C.

But as a matter of practice, most terminations are marked 75C, and the marking overrides the default.
 
AC\DC said:
And why can’t you use #6 at 7amps as long as it’s wire rated at 90 and both end of your connections are 90 degree.
Unless I looked wrong 6 copper at 90% is 75 amps
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I know we’ve swerved all over the place in this thread, but remember that the original post is about NM. 55A is it.
 
Bashacses said:
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UL Listing on 125 amp or less breakers you should be using the 60 column cable rating.
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This is incorrect. It sounds like a rationalization or misunderstanding of 110.14(C) but it gets the details wrong. First, it is not the breaker listing that is the issue. It is simply an NEC rule. Second, that NEC rule has an alternative to always using the 60C column (and it's probably not the breaker that would disqualify using that alternative). Third, the rule hinges on 100A or 1awg wire (or smaller), not 125A.
 
LarryFine said:
Is it because of motor load allowances?
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That's a good point. With heavy motor loads for a pool, can you size the feeder to the ampacity requirement (say it is 54 amps) but use a breaker with the higher combination motor breaker rating in 430.62? However, it may be a reach to be able to use a 70A breaker unless the pool has a large pump motor on a 20A or larger breaker. Also don't know if 430.62 is allowed to be used for a mixed feeder the has motors, lights, and a convenience outlet or two. I would think so based on the reference to the ampacity calculation for a multiple motor/load application.
 
AC\DC said:
The problem is the nmb

if the wires rated for 90 degrees. I have put in splices before so I can use the 90 degree coulmb and the. Transition to a larger wire to the breaker
Click to expand...
The conductors in NM are required to be 90°C conductors, but the only thing you can use the 90°C ampacity for is ampacity adjustment and/or ampacity correction. You can't use the splice method to use NM at an ampacity that exceeds the ampacity found in the 60°C column.
 
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