Branch circuit through hub in top of 3R loadcenter

[bobster789]

I have a Eaton NEMA-3R loadcenter (meter feed is through the bottom right knockout) installed on the brick veneer of the outside of my home. The top hub is currently unused. I would like to install a DS200H2 hub and run a Carlon PVC conduit about 48" through the soffit above the panel. The conduit will be used to protect 4 new branch circuits run with #12 THWN-2 stranded conductors to a junction box in the soffit space. From there I will extend these circuits using 12/2 w/g NM cable. Are there any code violations with doing this?

 

[don_resqcapt19]

I think the only code compliant way to do that would be to use a rigid nipple in the conduit hub and a female adapter to switch to PVC. Male adapters have not been evaluated for use with female threads.

 

[wwhitney]

I think the only code compliant way to do that would be to use a rigid nipple in the conduit hub and a female adapter to switch to PVC. Male adapters have not been evaluated for use with female threads.

I don't believe that's correct for PVC. UL 651 covers PVC fittings and conduit (but not PVC conduit bodies), and Section 1.5.3 in the Scope chapter says that "Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to: . . . (b) A threaded metal hub or fitting on a metal box"

I think that's definitive, but since I spent some time looking at UL 514B on Conduit, Tubing and Cable Fittings, I'll also note:

UL 514B 3.23 defines a Hub as "A fitting intended for use with threaded conduit for connection to an enclosure." No requirement for it to metallic conduit.

Carlon's catalog describes a Male Terminal Adapter as "For adapting nonmetallic conduits to boxes, threaded fittings, metallic systems. Male threads on one end, socket end on other." A hub is a threaded fitting.

Cheers, Wayne

P.S. This is just for PVC. For, say, EMT, a regular EMT connector is intended for connecting to a sheet metal box, and will come with a locknut on it to signify that (and its threadig may be neither NPS nor NPT), as per UL 514B 5.8.1.5. There are special EMT male adapters that have tapered threads that have been investigated to use with female threaded fittings.

Cheers, Wayne

 

[bobster789]

I don't believe that's correct for PVC. UL 651 covers PVC fittings and conduit (but not PVC conduit bodies), and Section 1.5.3 in the Scope chapter says that "Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to: . . . (b) A threaded metal hub or fitting on a metal box"

I think that's definitive, but since I spent some time looking at UL 514B on Conduit, Tubing and Cable Fittings, I'll also note:

UL 514B 3.23 defines a Hub as "A fitting intended for use with threaded conduit for connection to an enclosure." No requirement for it to metallic conduit.

Carlon's catalog describes a Male Terminal Adapter as "For adapting nonmetallic conduits to boxes, threaded fittings, metallic systems. Male threads on one end, socket end on other." A hub is a threaded fitting.

Cheers, Wayne

P.S. This is just for PVC. For, say, EMT, a regular EMT connector is intended for connecting to a sheet metal box, and will come with a locknut on it to signify that (and its threadig may be neither NPS nor NPT), as per UL 514B 5.8.1.5. There are special EMT male adapters that have tapered threads that have been investigated to use with female threaded fittings.

Cheers, Wayne

Thanks, Wayne! I was also wondering whether there was any restriction on using the hub in the top for branch circuits (vs. service feeders).

 

[J2H]

I don't believe that's correct for PVC. UL 651 covers PVC fittings and conduit (but not PVC conduit bodies), and Section 1.5.3 in the Scope chapter says that "Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to: . . . (b) A threaded metal hub or fitting on a metal box"

I think that's definitive, but since I spent some time looking at UL 514B on Conduit, Tubing and Cable Fittings, I'll also note:

UL 514B 3.23 defines a Hub as "A fitting intended for use with threaded conduit for connection to an enclosure." No requirement for it to metallic conduit.

Carlon's catalog describes a Male Terminal Adapter as "For adapting nonmetallic conduits to boxes, threaded fittings, metallic systems. Male threads on one end, socket end on other." A hub is a threaded fitting.

Cheers, Wayne

P.S. This is just for PVC. For, say, EMT, a regular EMT connector is intended for connecting to a sheet metal box, and will come with a locknut on it to signify that (and its threadig may be neither NPS nor NPT), as per UL 514B 5.8.1.5. There are special EMT male adapters that have tapered threads that have been investigated to use with female threaded fittings.

Cheers, Wayne

Wayne, that's quite interesting. Wondering if the same would apply for LTFNMC and a weatherproof receptacle box("Bell") box. Certainly makes since that this would not be permitted for LTFMC, or EMT if UL did not test the fittings for grounding continuity. That said, it seems like perhaps there should be an exception for an EMT fitting threaded into a box, or a hub, if there is a bonding jumper.

 

[don_resqcapt19]

I don't believe that's correct for PVC. UL 651 covers PVC fittings and conduit (but not PVC conduit bodies), and Section 1.5.3 in the Scope chapter says that "Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to: . . . (b) A threaded metal hub or fitting on a metal box"

I think that's definitive, but since I spent some time looking at UL 514B on Conduit, Tubing and Cable Fittings, I'll also note:

UL 514B 3.23 defines a Hub as "A fitting intended for use with threaded conduit for connection to an enclosure." No requirement for it to metallic conduit.

Carlon's catalog describes a Male Terminal Adapter as "For adapting nonmetallic conduits to boxes, threaded fittings, metallic systems. Male threads on one end, socket end on other." A hub is a threaded fitting.

Cheers, Wayne

P.S. This is just for PVC. For, say, EMT, a regular EMT connector is intended for connecting to a sheet metal box, and will come with a locknut on it to signify that (and its threadig may be neither NPS nor NPT), as per UL 514B 5.8.1.5. There are special EMT male adapters that have tapered threads that have been investigated to use with female threaded fittings.

Cheers, Wayne

Yet the UL Guide Information for conduit fittings says:

Fittings with internal female threads (e.g., hubs, conduit bodies, couplings) have only been investigated for use with threaded rigid conduit.

Not even IMC...only RMC .....there is a lot of conflicting information to be found in the various documents.

 

[wwhitney]

Yet the UL Guide Information for conduit fittings says: "Fittings with internal female threads (e.g., hubs, conduit bodies, couplings) have only been investigated for use with threaded rigid conduit. "

Not even IMC...only RMC .....there is a lot of conflicting information to be found in the various documents.

A few comments:

I don't see "threaded rigid conduit" as meaning RMC. Indeed the title of UL 6 is "Electrical Rigid Metal Conduit -- Steel"--the word metal is part of the name. So "threaded rigid conduit" just means any conduit that is (a) rigid and (b) has a threaded end, with no implication of metal. The upshot of the earlier references to a PVC Terminal (Male) Adapter is that it puts a threaded end on rigid PVC conduit. That is compatible with the UL Guide sentence you quoted.

This is in contrast to a Connector, which is intended for use with a box, per the definitions section of the applicable UL standards. Indeed, a PVC box adapter is not threaded at all. So for PVC, at least, we have two different fittings, a Connector, and a Terminal Adapter, with two different purposes and ranges of use.

Also, you can have a situation where "Fittings of type X are investigated only for use with Y," and "Fittings of type Z are investigated for use with A, B, C, and fittings of type X." That means when the type X fitting is listed, they just test it with Y, but when the type Z fitting is listed, it does get tested with the type X fitting. So as long as the listing standard for either component involves testing to validate the combination, it seems to me that suffices. I see no need for the combination to be blessed twice, once under each of the two listing standards

Cheers, Wayne

 

[infinity]

I don't see "threaded rigid conduit" as meaning RMC

IMC is not rigid conduit it is intermediate metal conduit. Just because it happens to be of rigid construction does not make it RMC.

I agree with Don. Someone with half a brain over at UL needs to tell them how to straighten out this mess.

 

[wwhitney]

IMC is not rigid conduit it is intermediate metal conduit. Just because it happens to be of rigid construction does not make it RMC.

RMC = "rigid metal conduit". UL and the NEC will use terminology exactly. So the phrase "rigid conduit" Don quoted does not mean RMC. It means any non-flexible conduit.

Cheers, Wayne

 

[infinity]

RMC = "rigid metal conduit". UL and the NEC will use terminology exactly. So the phrase "rigid conduit" Don quoted does not mean RMC. It means any non-flexible conduit.

Cheers, Wayne

RMC and IMC have completely different construction and separate code articles. So the reference to threaded rigid conduit in Don's post doesn't apply to IMC.

 

[wwhitney]

RMC and IMC have completely different construction and separate code articles. So the reference to threaded rigid conduit in Don's post doesn't apply to IMC.

The reference to "thread rigid conduit" in Don's post is not a reference to RMC. They would have written "threaded rigid metal conduit" if they meant that. The UL Guide information does not use trade slang.

Cheers, Wayne

 

[infinity]

The reference to "thread rigid conduit" in Don's post is not a reference to RMC. They would have written "threaded rigid metal conduit" if they meant that. The UL Guide information does not use trade slang.

Cheers, Wayne

You're ignoring the fact that IMC is not threaded rigid conduit.

 

[don_resqcapt19]

RMC = "rigid metal conduit". UL and the NEC will use terminology exactly. So the phrase "rigid conduit" Don quoted does not mean RMC. It means any non-flexible conduit.

Cheers, Wayne

The language says threaded rigid conduit, but the only two that the NEC permits to be threaded are RMC and IMC. It is very clear to me that UL means conduit covered by Article 344.
Again, we will not agree

 

[wwhitney]

It is very clear to me that UL means conduit covered by Article 344.

OK, so I downloaded the 2015-2016 UL White Book (last version that is available as a PDF), and it uses the phrase "threaded rigid conduit" 22 times, and the phrase "rigid metal conduit" 26 times. Briefly looking at the context of the usages, it does appear that you are correct and that UL is using "threaded rigid conduit" as a synonym for "rigid metal conduit". This is obviously poor practice; every usage of "threaded rigid conduit" should simply be replaced with the defined term "rigid metal conduit."

So in this case with further evidence we are able to agree. : - )

However, that still leaves my second argument. Namely that to use product X with product Y, only one of the listing standards has to investigate or cover the combination, not both. So while the hub / PVC terminal adapter is not investigated under the standard for the hub, it is investigated under the standard for the PVC terminal adapter. That makes the combination acceptable.

Cheers, Wayne

 

[don_resqcapt19]

OK, so I downloaded the 2015-2016 UL White Book (last version that is available as a PDF), and it uses the phrase "threaded rigid conduit" 22 times, and the phrase "rigid metal conduit" 26 times. Briefly looking at the context of the usages, it does appear that you are correct and that UL is using "threaded rigid conduit" as a synonym for "rigid metal conduit". This is obviously poor practice; every usage of "threaded rigid conduit" should simply be replaced with the defined term "rigid metal conduit."

So in this case with further evidence we are able to agree. : - )

However, that still leaves my second argument. Namely that to use product X with product Y, only one of the listing standards has to investigate or cover the combination, not both. So while the hub / PVC terminal adapter is not investigated under the standard for the hub, it is investigated under the standard for the PVC terminal adapter. That makes the combination acceptable.

Cheers, Wayne

I really doubt the terminal adapter is actually evaluated for use with a conduit hub.

 

[infinity]

So while the hub / PVC terminal adapter is not investigated under the standard for the hub, it is investigated under the standard for the PVC terminal adapter. That makes the combination acceptable.

I was always under the impression that the limit for hubs to threaded RMC was due to the bonding connection required with a tapered thread. Since that is not an issue with PVC a terminal adapter even with straight threads should be permitted.

 

[J2H]

I was always under the impression that the limit for hubs to threaded RMC was due to the bonding connection required with a tapered thread. Since that is not an issue with PVC a terminal adapter even with straight threads should be permitted.

I’ve thought the same thing for whatever it’s worth, but what is truly permitted I realize could be a different story.

 

[wwhitney]

I really doubt the terminal adapter is actually evaluated for use with a conduit hub.

It's right there in my first post of the thread. UL 651 cover "Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings." And section 1.5.3 of that standard says "Externally-threaded adapters (also referred to as terminal adapters) covered by these requirements are fittings intended for joining a length of rigid PVC conduit or elbow to: . . . (b) A threaded metal hub or fitting on a metal box"

So PVC terminal adapter to metal hub is a permitted combination under the UL standard on PVC fittings. The guide info you quoted today pertains to fittings listed under UL 514B "Conduit, Tubing, and Cable Fittings," which only covers the metal hub.

Cheers, Wayne