Non listed expansion coupling.

[electrofelon]

I frequently make my own expansion couplings/slip riser by using different sizes of PVC. For example a 2 1/2 schedule 40 fits nicely over 2". In fact the factory slip risers are exactly just a piece of two and a half schedule 40 with the other end shrunk down and a 2-inch TA on it. So I got called on this and was told I needed to use a listed expansion fitting. Here was my response:

Ok XYZ thanks. We will have to agree to disagree on this. I see nothing in the NEC prohibiting my method. While certainly I agree that 352.10 requires PVC fittings to be listed,. I contend that all of these fittings are listed, and there is no requirement that A fitting be listed for the purpose. Also note there are other ways to comply with the expansion requirement besides an expansion coupling. See 300.5(J), particularly the informational note that follows.

What does the group think?

 

[K8MHZ]

I frequently make my own expansion couplings/slip riser by using different sizes of PVC. For example a 2 1/2 schedule 40 fits nicely over 2". In fact the factory slip risers are exactly just a piece of two and a half schedule 40 with the other end shrunk down and a 2-inch TA on it. So I got called on this and was told I needed to use a listed expansion fitting. Here was my response:

Ok XYZ thanks. We will have to agree to disagree on this. I see nothing in the NEC prohibiting my method. While certainly I agree that 352.10 requires PVC fittings to be listed,. I contend that all of these fittings are listed, and there is no requirement that A fitting be listed for the purpose. Also note there are other ways to comply with the expansion requirement besides an expansion coupling. See 300.5(J), particularly the informational note that follows.

What does the group think?

The definitions state that listed means ".....suitable for a specified purpose".

 

[electrofelon]

The definitions state that listed means ".....suitable for a specified purpose".

It's an interesting distinction. I can't tell you where at the moment, but I am nearly certain the NEC does use the phrase "listed for the purpose" on occasion.

Also, my reading of 300.5(J) and the information note that follows seems to be flexible (pun) on how the result is achieved. There is nothing stating (something like) "an approved/listed expansion fitting shall be used"

 

[ActionDave]

We used to make our own expansion fittings when they were not so easy to get from the local supply house, but have not done that for a decade or more.

Digging into the code my 2020 edition 352.6 says PVC conduit, factory elbows, and associated fittings shall be listed.

Section 352.44 is titled Expansion Fittings and as far as I can tell they are the only fitting with their own code section. So does that mean that TAs and couplings are not associated?

 

[electrofelon]

We used to make our own expansion fittings when they were not so easy to get from the local supply house, but have not done that for a decade or more.

Digging into the code my 2020 edition 352.6 says PVC conduit, factory elbows, and associated fittings shall be listed.

Section 352.44 is titled Expansion Fittings and as far as I can tell they are the only fitting with their own code section. So does that mean that TAs and couplings are not associated?

There is some gray area as to what "associated" means for sure. Is a strap associated?

352.44 seems to apply just to situations where the conduit system expands or contracts beyond a certain amount. In those cases it seems clear an expansion fitting is required. I didn't mention this specifically in the OP, but for the purposes of this discussion I am talking about allowing flexibility for ground settling or heaving, where there are other options besides expansion fittings (again see 300.5(J) and the I.N. that follows).

 

[infinity]

Arlington makes a fitting designed for the field use of two different sized conduits to make your own expansion fitting.

https://www.aifittings.com/catalog/miscellaneous/slip-meter-riser-fitting/NM2520

 

[kwired]

Arlington makes a fitting designed for the field use of two different sized conduits to make your own expansion fitting.

https://www.aifittings.com/catalog/miscellaneous/slip-meter-riser-fitting/NM2520

AFAIK they just have one size. It is like a male PVC adapter but has 2 inch male thread and 2.5 inch slip/glue on other end. Yes instructions say to use your own piece of 2.5" sch 40 to complete the assembly. I have on occasion just used a 2.5 MA and piece of sch 40 to do the same thing. Not been called on it but many those cases weren't something that was to be inspected either.

 

[kwired]

There is some gray area as to what "associated" means for sure. Is a strap associated?

352.44 seems to apply just to situations where the conduit system expands or contracts beyond a certain amount. In those cases it seems clear an expansion fitting is required. I didn't mention this specifically in the OP, but for the purposes of this discussion I am talking about allowing flexibility for ground settling or heaving, where there are other options besides expansion fittings (again see 300.5(J) and the I.N. that follows).

One issue I have with ground settling or heaving is an expansion fitting might protect the raceway but the conductors inside don't expand or collapse and can still place strain on the terminations in a cabinet, meter socket, etc.

 

[electrofelon]

One issue I have with ground settling or heaving is an expansion fitting might protect the raceway but the conductors inside don't expand or collapse and can still place strain on the terminations in a cabinet, meter socket, etc.

Well yes, you need to provide services play in the conductors. I prefer top feed panels for this so you have a nice loop

 

[electrofelon]

Arlington makes a fitting designed for the field use of two different sized conduits to make your own expansion fitting.

https://www.aifittings.com/catalog/miscellaneous/slip-meter-riser-fitting/NM2520

Right. So I can use that but some will say I can't do the service thing just with a 2.5 TA?

 

[kwired]

Right. So I can use that but some will say I can't do the service thing just with a 2.5 TA?

It works but some those inspectors you just want to slap on the nose with a rolled up code book won't like it.

 

[kwired]

Well yes, you need to provide services play in the conductors. I prefer top feed panels for this so you have a nice loop

Still puts strain on terminals. top feed panel or meter helps though. Conductors larger than ~2/0 (other than ultra fine stranded) don't flex that easily that they won't put some strain on things.

 

[electrofelon]

Still puts strain on terminals. top feed panel or meter helps though. Conductors larger than ~2/0 (other than ultra fine stranded) don't flex that easily that they won't put some strain on things.

IIRC all 3R load centers seem to have lugs or breaker on top. if it's a true panelboard, typically the guts can just be flipped to go either way. Just if it has a main breaker that is oriented vertically, might have to flip that to comply with the down is off rule.

 

[kwired]

IIRC all 3R load centers seem to have lugs or breaker on top. if it's a true panelboard, typically the guts can just be flipped to go either way. Just if it has a main breaker that is oriented vertically, might have to flip that to comply with the down is off rule.

Yes. suppose it varies but my true panelboards are usually assembled in field and you orient the main breaker accordingly, even need to remove lugs from them at times and install connecting links to the panel bus.