Romex or SE for 60amp heat pump

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timt72

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If we can put a 60 amp breaker on #6/2 romex can we hook it to a electric furnace that has a fla of 58 amps at 220v and if not why?
 
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the "next size breaker" rule does not allow you to exceed the ampacity of the cable. 55 amp wire is limited to a 55 amp load.
 
charlie said:
Keep in mind that Type NM cable is not permitted to be used in an outside enclosure. :)
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Yeah right, That is the most outrageously ignored rule ever. How many people do you think run UF cable as their homeruns to outdoor panels of to a/c discos. I have never seen it. I am not arguing with you but I think there is an unwritten rule here that permits that install. Once you leave the breaker box/ disco then it is enforced around here.
 
timt72 said:
If we can put a 60 amp breaker on #6/2 romex can we hook it to a electric furnace that has a fla of 58 amps at 220v and if not why?
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To answer your question directly-- If you are under the 2008 code then you cannot run 6/2 nm nor #6 SEU cable to that heater. Now under the 2005 you could run SE cable but not NM.
 
charlie said:
Keep in mind that Type NM cable is not permitted to be used in an outside enclosure. :)
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In my part of the world, interior wireing methods are allowed to a jbox on the exterior ( a/c disc. WP box for recp. Jbox for post light etc.) and changed over at that point.
 
charlie said:
Keep in mind that Type NM cable is not permitted to be used in an outside enclosure. :)
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That has been done for years feeding a/c disco. What did the code making panel think was going to happen to NM is exposed to outside air. Sometimes I think those code panels need to get more freah air :rolleyes:
 
timt72 said:
If we can put a 60 amp breaker on #6/2 romex can we hook it to a electric furnace that has a fla of 58 amps at 220v and if not why?
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I'd say you can't use #6 anything to connect a 58A heater. Space heating is a continuous load, so the ampacity required for a branch circuit is 58*1.25 = 72.5 amps. For copper, you're looking at #4 75C conductors, or #3 60C conductors.
 
wawireguy said:
I'm curious where it says you can't use NM in a outside enclosure?
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I am not sure that the nec states that nm cannot be used in an outside enclosure but it does state that the interior of raceways above ground in wet locations shall be considered wet location. Nm is not allowed in wet locations. I think the same would hold true for a panelboard in a wet location.
Art. 300.9 Raceways in Wet Locations Above Grade.
Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location. Insulated conductors and cables installed in raceways in wet locations abovegrade shall comply with 310.8(C).
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suemarkp said:
I'd say you can't use #6 anything to connect a 58A heater. Space heating is a continuous load, so the ampacity required for a branch circuit is 58*1.25 = 72.5 amps. For copper, you're looking at #4 75C conductors, or #3 60C conductors.
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I suspect the op is talking about a 10 kw furnace where it is 58 amps with the 125%. I have seen a few that were 56 or 57 amps after the 125% was added in. ((10000/240)+(blower load)) * (125%)= 58 amps . Just a guess.
 
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