10 kw heat strip

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SeanKelly

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Ran into a problem yesterday with wire sizing. I've been called on this before and need some advice. Walked onto apartment job and saw guys pulling #4 SE aluminum to the furnaces. The furnaces were already made up in one building and pulled in the next(16 units total). The next day I walked with the inspector and he said the #4 is too small because we have to rate it off 75 degree charts for the lugs. Min ampacity is 58.5 MOPD is 60. Went into the code book and saw 6-2 copper is too small. Then i figured we would run 6-2 SE copper. Called the inspector and he said SE cable if it runs through the interior of a building has to be rated off 60 degree chart. I knew the aluminum was going to fail and I know the 6-2 nmb is too small. Do I have to run 4-2 or are their any exceptions or anything else I am missing? Thx
 
welcome to '08 :D
It has taken me years to get the HVAC contractors properly address the MCA issue which most accomplished by SE cable vs NM and now we get to re-train:D
 
SE cable isn't even permitted to be used to feed those heat strips in that occupancy type anyhow, since it will be exposed inside at least for part of the run to the AHU.
 
SE cable isn't even permitted to be used to feed those heat strips in that occupancy type anyhow, since it will be exposed inside at least for part of the run to the AHU.

how so? (not challanging, just wanting knowledge)
 
It's amazing to me that for all these years, type SE cable has performed just fine using the 75 degree column ratings.

Suddenly, with the new code it's a fire hazard? :-?

How many houses have burned down with "undersized" but compliant SE cable installations?? :mad:
 
It's amazing to me that for all these years, type SE cable has performed just fine using the 75 degree column ratings.

Suddenly, with the new code it's a fire hazard? :-?

How many houses have burned down with "undersized" but compliant SE cable installations?? :mad:


Probably none. Someone thought that it would be a good idea to have two similar cables (NM and SE) with the same 60 degree rating. The CMP agreed. I'm hoping that there are many proposals for the 2011 NEC to go back to the 75 degree rating which worked fine for decades.
 
electric heat

electric heat

Be careful, some electric heat packs, do not allow aluminum to be used. Should alwayse use copper, If you can use romex then use 6-2, if you cannot use romex then use 6-2 mc. Make sure their is disconnect within proper distance,
 
... Someone thought that it would be a good idea to have two similar cables (NM and SE) with the same 60 degree rating. The CMP agreed. I'm hoping that there are many proposals for the 2011 NEC to go back to the 75 degree rating which worked fine for decades.

What possibility would there be to make both SE and NM cables permissible with the 75 degree ratings? Since NM is rated 90 degrees these days, they could stipulate that NM-B would be acceptable applied with the 75 degree column ratings.... :confused:
 
What possibility would there be to make both SE and NM cables permissible with the 75 degree ratings? Since NM is rated 90 degrees these days, they could stipulate that NM-B would be acceptable applied with the 75 degree column ratings.... :confused:

Because of the uses of nm inside with much thermal insulation around it, nm is rated 60C max but 90C is allowed for derating. See art. 334.80. In the 2008 code se cable has been assigned the same conditions as nm when it is installed as a feeder or branch circuit inside a building. 60C for both NM and Se cable as of 08 nec.
 
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