Conduit and Tubing: Do these words mean things?

[bwat]

I hope this topic hasn't been beat to death here.

Posts and responses come up every now and then that will say something like "EMT is tubing, not conduit". And I often want to ask: "so what?". Does this actually change anything? Is this only stated because the "t" stands for "tubing", but in practice it's meaningless to differentiate? If tomorrow everything we know as EMT was all of the sudden called EMC (C for conduit), would anything change?

I understand that RMC, IMC, EMT, PVC Sch. 40, PVC Sch. 80, etc. are all different things, but whether something is categorized as conduit or tubing doesn't seem to matter. Each raceway type has its own installation requirements, and there isn't something in the NEC such as "Installations of A, B, and C are permitted with conduit but not with tubing" (or vice versa) that I am aware of.

To make matters worse and play devil's advocate a little bit, the NEC doesn't define "conduit" or "tubing" and if you look up "conduit" on m-w.com, the 2nd definition lists "a pipe, tube, or tile for protecting electric wires or cables .".... so when anyone calls out that EMT is tubing and not conduit, according to available definitions couldn't you say that tubing is a type of conduit, so yes EMT is conduit?

A lot of questions here, but it really comes down to: other than the fact that the "t" stands for "tubing" in EMT, does it matter whether it is tubing or conduit?

I like to consider myself a "words mean things" kind of a guy. In this context, it means that I recognize that "tubing" and "conduit" is used, and some people like to point this out, so there must be a reason to differentiate... but maybe there isn't.

 

[ActionDave]

I agree with you. The rumor I heard was EMT was a term that started as a marketing gimmick.

 

[electrofelon]

I dont think the NEC uses the word "conduit" much. The article 352 definition of PVC doesnt use the word "conduit". I also cant think of any instances where the NEC uses the word "conduit" in such a way that might restrict the use of a "tubing".

I do recall the "EMT isnt conduit" thing coming up on here before, but I cant remember why it purportedly mattered.

 

[dkidd]

I dont think the NEC uses the word "conduit" much. The article 352 definition of PVC doesnt use the word "conduit". I also cant think of any instances where the NEC uses the word "conduit" in such a way that might restrict the use of a "tubing".

I do recall the "EMT isnt conduit" thing coming up on here before, but I cant remember why it purportedly mattered.

A good example of the distinction is

314.23
(E) Raceway-Supported Enclosure, Without Devices,
Luminaires, or Lampholders. An enclosure that does not
contain a device(s), other than splicing devices, or supports
a luminaire(s), a lampholder, or other equipment and is
supported by entering raceways shall not exceed 1650 cm3
(100 in.3) in size. It shall have threaded entries or identified
hubs. It shall be supported by two or more conduits
threaded wrenchtight into the enclosure or hubs. Each conduit
shall be secured within 900 mm (3 ft) of the enclosure,
or within 450 mm (18 in.) of the enclosure if all conduit
entries are on the same side.

 

[Jraef]

This article, written by the way by our own Mike Holt, supports the “tubing is not conduit” side. I was in the “same” camp until reading this, now I am wondering.

StackPath

 

[infinity]

Is there really a need for a distinction between the two? They're both circular raceways.

 

[ActionDave]

This article, written by the way by our own Mike Holt, supports the “tubing is not conduit” side. I was in the “same” camp until reading this, now I am wondering.

StackPath

That article didn't say anything about conduit vs tubing other than both words are used in the nec and neither is defined.

 

[Little Bill]

One can be threaded and one can't

 

[infinity]

One can be threaded and one can't

True, but you can't thread FMC either which is a "conduit" so why do we need a distinction between tubing and conduit?

 

[Little Bill]

True, but you can't thread FMC either which is a "conduit" so why do we need a distinction between tubing and conduit?

You asked about distinction between the two, I was replying to that.

 

[bwat]

Another monkey wrench: PVC is referred to as conduit in art. 352

(at least in 2017 it is)

 

[ActionDave]

True, but you can't thread FMC either which is a "conduit" so why do we need a distinction between tubing and conduit?

Yup. And you can use some conduits in places where others can't be so what difference does it make if it's tubing or not.

 

[zbang]

I'm going to wildly speculate that when thin-wall pipe was introduced to the trade, it was marketed as "tubing" instead of "pipe" since it didn't need threading and was easier to bend, thus needing less labor to install.

Also, thin-wall circular metal shapes are often called tubing and thicker-walled ones pipe.

 

[hbiss]

I'm going to wildly speculate that when thin-wall pipe was introduced to the trade, it was marketed as "tubing" instead of "pipe" since it didn't need threading and was easier to bend, thus needing less labor to install.

EMT was invented by Jack Benfield who marketed it as an easier to install less labor alternative to threaded RMC which was pretty much all that was available back then. It was Jack who called it EMT which stands for Electrical Metallic Tubing. Probably for marketing reasons because tubing sounds a lot easier to work with than rigid conduit.

Personally I don't know what all the fuss is about. EMT has been around for a long time. If wire is run through it it's conduit or a raceway. As long as each different type is used in compliance with it's design and listing all is good.

-Hal

 

[jaggedben]

A good example of the distinction is

314.23
(E) Raceway-Supported Enclosure, Without Devices,
Luminaires, or Lampholders. An enclosure that does not
contain a device(s), other than splicing devices, or supports
a luminaire(s), a lampholder, or other equipment and is
supported by entering raceways shall not exceed 1650 cm3
(100 in.3) in size. It shall have threaded entries or identified
hubs. It shall be supported by two or more conduits
threaded wrenchtight into the enclosure or hubs. Each conduit
shall be secured within 900 mm (3 ft) of the enclosure,
or within 450 mm (18 in.) of the enclosure if all conduit
entries are on the same side.

Is that really an 'example' or is it the only instance where it matters?

Also is FMC 'conduit' and wouldn't it be crazy to support enclosures with FMC instead of EMT?

 

[synchro]

I found this from the 1929 Journal of the AIEE:

 

[PaulMmn]

Remember-- the C in PVC stands for "Chloride," not "Conduit!"

 

[infinity]

Remember-- the C in PVC stands for "Chloride," not "Conduit!"

Good point, but also in Article 352 it's called Rigid Polyvinyl Chloride Conduit (PVC) so the NEC is calling it a conduit.

 

[Jraef]

That article didn't say anything about conduit vs tubing other than both words are used in the nec and neither is defined.

Maybe you didn't get to the end...

Sidebar: Conduit Vs. Tubing

Many people erroneously refer to electrical metallic tubing (EMT) as “conduit.” EMT is actually a tubing rather than a conduit. Conduit and tubing are two different wiring methods that differ in application and installation requirements, although neither is defined by the Code.


In the NEC, the phrase “conduit or tubing” appears multiple times, indicating a choice between two different things. To see an example of this, look at Table 4 of Chapter 9.


The term “raceway” can be used to refer to an enclosed wiring method, including both conduit and tubing. Just remember that there are other types of raceway as well, such as wireways.

 

[tom baker]

EMT was invented by Jack Benfield who marketed it as an easier to install less labor alternative to threaded RMC which was pretty much all that was available back then. It was Jack who called it EMT which stands for Electrical Metallic Tubing. Probably for marketing reasons because tubing sounds a lot easier to work with than rigid conduit.

Personally I don't know what all the fuss is about. EMT has been around for a long time. If wire is run through it it's conduit or a raceway. As long as each different type is used in compliance with it's design and listing all is good.

-Hal

And Jack Benfield invented the Benfield bender to use with EMT. He traveled the country demonstrating the bender to electricians to show how easy it was to bend EMT. Up until that time, electricians used a Hicky. Electricians were distrustful EMT, and it took some time for it become accepted.
There is good background on this in the Benfield bending manual.