Difference between a conduit and a duct?

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stcalle

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Could someone explain the difference between a conduit and a duct? For how I saw it, the word duct is usually used when you have some sort of underground situation or where you bury the conduit. I mostly hear the word duct in reference to service conductors. I hear the world conduit in all other instances.

thanks
 
Thats a good question, based on what I understand.
They both are raceways, but a duct is typically used only for underground conductors and that is due to the nature of a duct (made of fiber or other materials that typically will not protect cables from physical harm). We can assume that no one will tamper underground cables.
 
Difference between a conduit and a duct?

Electrical ducts is defined in section 310.60(A) as follows:
As used in Article 310, electrical ducts shall include any of the electrical conduits recognized in Chapter 3 as suitable for use underground; other raceways round in cross section, listed for underground use, and embedded in earth or concrete.
 
It probably depends on the application. My memory might be a bit rusty, but I think the NESC says that conduit is singular (i.e. one pipe) and a duct is a series of conduits (i.e. lots of pipes).

Someone with a copy of the NESC in front of them could verify or refute pretty easily, but even then it would only apply to you if you are putting in underground distribution cable. :)
 
drbond24 said:
It probably depends on the application. My memory might be a bit rusty, but I think the NESC says that conduit is singular (i.e. one pipe) and a duct is a series of conduits (i.e. lots of pipes).

Someone with a copy of the NESC in front of them could verify or refute pretty easily, but even then it would only apply to you if you are putting in underground distribution cable. :)
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I think the NESC is referring to a duct hole (innerduct), but a duct is a raceway. The code reference seems to have the meaning that duct refers to kind of conduit or race used solely for underground distribution. As far as I know a series of ducts is known as a duct bank.
 
Bus duct

Bus duct

Not all reference to duct indicates underground. Bus duct within a building contains electrical conductors.
 
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