fixed heat calculation

Status
Not open for further replies.

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
The reason i ask is Table 240.3 lists Fixed electric space heating equipment with Art 424 so doesn't that mean that Art 240.4D doesn't apply here since fixed electric space heating is listed as specific equipment. Someone cited this article in reference to #12 awg conductors and not exceeding 20a O.C.P was the reason I asked.

Those items referenced in T240.3 must abide by article 240 overcurrent protection rules. Those in 240.4(G) do not need to follow the limitation of small conductors in 240.4(D)
 

kwired

Electron manager
Location
NE Nebraska
The reason i ask is Table 240.3 lists Fixed electric space heating equipment with Art 424 so doesn't that mean that Art 240.4D doesn't apply here since fixed electric space heating is listed as specific equipment. Someone cited this article in reference to #12 awg conductors and not exceeding 20a O.C.P was the reason I asked.

Like I said I looked at 424, I just looked at it again. I do not find anything that changes what has been discussed in this thread. The only thing there that applies is the fact that it mentions fixed electric space heating is to be considered a continuous load. After that the general rule is 240 and 310 for conductor sizing and overcurrent protection if a specific article does not have its own requirements or exceptions.
 

Smart $

Esteemed Member
Location
Ohio
The reason i ask is Table 240.3 lists Fixed electric space heating equipment with Art 424 so doesn't that mean that Art 240.4D doesn't apply here since fixed electric space heating is listed as specific equipment. Someone cited this article in reference to #12 awg conductors and not exceeding 20a O.C.P was the reason I asked.
You are correct... on how to start the determination process.

However, 424.3(B) says these loads shall be considered a continuous load for branch-circuit sizing... and when we get to 424.22(A) for overcurrent protection and 424.24(D), we get sent to Article 210, which will then send us to 240.4(D)...
 

G._S._Ohm

Senior Member
Location
DC area
Watching how this thread is evolving from an outsider's viewpoint I have to say that the NEC, as written, seems to put an 'undue burden of interpretation' on knowledgeable and experienced users - you all.

Publishing rationales for the rules may help, but since the NEC won't even say what is an objectionable current, I wouldn't hold my breath.
 
Status
Not open for further replies.
Top