Min. Cir Ampacity 30.9

[Buck Parrish]

Yes maximum size breaker 50 minimum ampacity 30.9. I would have used #10 before.

 

[Dennis Alwon]

but I thought he could only use this wire for the given application (article 440) under 2 conditions:
1) 60 degree column works (it doesn't, he needs next size #8)
2) per 440 (or 430 per 440.7), the unit is marked and says on the label "max size breaker 50A" (he didn't say this but I am guessing everyone assumed it ?)

I am not sure what you are asking. What is "this wire" I put it in bold in your response.

 

[Dennis Alwon]

Yes maximum size breaker 50 minimum ampacity 30.9. I would have used #10 before.

#10 would be fine if it were piped.

 

[augie47]

#10 would be fine if it were piped.

thats a great point. all I need to do is put my NM in a pipe then :grin:
(sorry, couldn't resist this morning)

 

[Buck Parrish]

So I'll use 8 to the disco. #10 to the unit.

All wire references are copper.

 

[iwire]

Scrape the .9 off of the tag.

 

[augie47]

Unless you want to change to some other wiring method than NM.

 

[Buck Parrish]

Scrape the .9 off of the tag.

Cool ! That's right.

 

[Cavie]

So I'll use 8 to the disco. #10 to the unit.

All wire references are copper.

You mean #10 thwn yes?

 

[iwire]

Unless you want to change to some other wiring method than NM.

I would imagine a cut of 10/2 MC will be less then a cut of 8/2 NM.

 

[LarryFine]

Oh, Thanks cheif !

I before E, except after C.

 

[Buck Parrish]

I before E, except after C.

Oh yeah, I should have know. I went to school in Raleigh.

 

[LarryFine]

Oh yeah, I should have know. I went to school in Raleigh.

Ask anyone who does crossword puzzles: names don't follow the rules of English.

 

[Buck Parrish]

You mean #10 thwn yes?

Yes #10 thhn
Under 05 It would have been okay to use the 75 degree column , am I right ????

 

[augie47]

You're right on the 75? as long as the termination are rated at 75? (most are), and your THHN would be fine for this INSIDE unit, but not an outside condensing unit.

 

[Dennis Alwon]

Yes #10 thhn
Under 05 It would have been okay to use the 75 degree column , am I right ????

If you are referring to nm then No, the nm rule for 60C has been around for a long time--

 

[Cavie]

Yes #10 thhn
Under 05 It would have been okay to use the 75 degree column , am I right ????

No RX has always been 60 degree. Can you say THWN? W stands for wet location.

 

[One-eyed Jack]

With all the talk about the 60 degree coloum in 310.16. I am second guessing my self. Is #10 Romex okay on a 240 v Geothermal Heat Pump? The breaker will be 50 amps, the minimum circuit ampacity is 30.9.
Is romex #10-2 WG okay?

The min cir ampacity means just that . Ref. 240.4 D (7) The max overcurrent protection is 30. This would be a code violation on wire size and ocp. The mfg. calculation 30.9 for min cir ampacity takes precedence over all other calculations. #8 would be required regardless of wire type. Then you could use the 50 amp ocp based on mfg. calculations.