Defenitions NEC vs NESC

[nonsinusoidal]

Can anyone provide feed back on why the NEC and NECS utilize the word "DUCT' and "CONDUIT" differently? It appears to be a contradiction on how such word is being utilized..... please advise

 

[alehman]

Conduit typically is listed by a recognized testing laboratory (e.g. UL), which is suitable for use in buildings as approved by the NEC.

Duct usually implies non-listed products - commonly used by utilities.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[rbulsara]

Perhaps, combination of a few things, not the least of which is the words used and "understood" in common (non-technical) language in the country of origin of these standards, namely USA.

NEC has defined "Electrical Duct" in Article 310.60 for the purpose of that article only as those conduits that are suitable for use underground. It specifically uses the word "electrical' to differentiate it from mechanical air ducts. The word "duct" is commonly used for air ducts for HVAC purposes, equally by techncial as well as common people in the USA.

This becomes more important as NEC by and large deals with indoor installation and mechanical ducts are often referenced.

NESC by and large deals with outdoor installations and seldom deals with mechanical air ducts. So it may be referencing the word duct just for electrical ducts. (I have not looked at a physical NESC book). For NESC, most of the outdoor installation is either overhead or underground in duct. This seems consistent with NEC.

Another point worth mentioning is although NEC uses the word conduit whenever it is engrained in common trade names (for example, rigid metal conduit), it prefers to use the word "raceway" for tubings, conduits or trays intended to hold conductors. Oddly, I have not heard any electrician use the word 'raceway' while speaking, but it is commonly used in writing specifications and on drawings.

Also codes and definitions are always evolving so this may change in the future.


Rafiq Bulsara

http://www.srengineersct.com

 

[alehman]

NEC defines raceway as any approved channel for holding wires, cables or busbars. I suppose that includes things like cable trays and surface raceway (Wiremold), etc. I too rarely hear "raceway" or the term "conductor", another NEC favorite, in the field.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[rbulsara]

Alan,

That "conductor" brings back a fuzzy memory of a heated discussion I was once drawn into, when a project manager and a spec reviewer, with structural backgrounds, were challenging the use of a spec title "Wires and Cables" and wanted me to define them and identify the difference between a 'wire' and a 'cable' or something along that line (it happened some 16 years ago). I do not remember the details but I was not able to convince them of my point of view, whatever it was. I had not invented those terms, after all.

Incidentally, soon after, the Masterpecs "revised" the spec section title to "Conductors and Cables" and I am still bemused by it as to what difference did it make?. Perhaps more in line with NEC.




Rafiq Bulsara

http://www.srengineersct.com

 

[nonsinusoidal]

It would be a benefit if the word "duct" and "conduit" is clarified by the NESC and NEC.

 

[alehman]

And "tubing" as in EMT.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[rbalex]

FWIW, Cable Trays are not raceways under the NRC Article 100 definition; they are a cable support system.

 

[rbalex]

With reference to the OP; the two documents are controlled by two different organizations. The NEC by the NFPA, the NESC by the IEEE. They are intended for two different audiences, read their Scope statements. As long as they are internally self-consistent, there is no compelling reason that they must conform to each other.