Run SER cable to junction box, the installation correct?

[winnie]

What are y'all building that requires 500 sets of 2/0 4C SER to be sent through a fire wall?

Modular apartments; presumably 500 separate fire walls:

Size the junction box for SER Cable Splicing

This is a multifamily building project with modular apt units. Each apt unit is delivered to the site from the factory as a module. It has a 4#2/0 & 1#1G AL SER Cable whip. We need to make connections between the SER cable from the modular unit to the 4#2/0 & 1#1G AL MC Cable from the building...

forums.mikeholt.com

 

[tortuga]

Modular apartments; presumably 500 separate fire walls:

Size the junction box for SER Cable Splicing

This is a multifamily building project with modular apt units. Each apt unit is delivered to the site from the factory as a module. It has a 4#2/0 & 1#1G AL SER Cable whip. We need to make connections between the SER cable from the modular unit to the 4#2/0 & 1#1G AL MC Cable from the building...

forums.mikeholt.com

I still want to know the 'Type', A multifamily modular apartment project is not automatically Type III, at least I dont think it is, just because it is modular. Modular construction is a construction method, not a construction type. If the project uses a Type IA podium and say a roof above is carried by a noncombustible steel structural frame, the upper portion could be Type II rather than Type III.

 

[zemingduan]

A piece of advise since your a professional engineer, and you asked, one thing to ask first is the 'Type' of construction and occupancy classification, as this limits the wiring methods you have available.
For example under the code rules for SE cable it points back to part II of the rules for NM cable which I believe is limited to Type III construction or higher.
The last time someone was asking me about a metal sleeve for SE cable thru a fire wall it turned out SER not an approved wiring method to begin with as they were in Type II-B Noncombustible (or limited-combustible) construction, and also another common gotcha for non-metallic wiring methods on commercial is in the chapter 5 articles like details in Articles 518 or 517.
Also I don't know about Philly but I have gleaned on here a few large cities like NYC and Chicago do not permit NM or SE cable in general not sure if thats the case still in 2026? but you might check what local rules Philly has?, as it says your in Philly.


Thats quite a few boxes.

Thanks for the advice. Yes, we always consider the type of construction. Many residential mid-rise building has type I or II construction for the basement and 1st floor. And the type III constructions for the upper levels residential part. In this case, we only allow NM cable inside the apt unit. And for this projects, these modules located at the upper levels which are Type III constructions.

 

[zemingduan]

I guess it's 1hr or 2hr rated dry wall, definitely not brick or concrete wall. This is also what I want to figure out. Do you have to use the sleeve? What is the clean way to pass the SER cable through that wall to the box that is attached to the opposite of the wall?

I realize that the SER cable pass through the wall and enters into the back of the box which is mounted on the opposite side of the wall. I think you are not able to install the SER connector in the hole/wall. It needs to be accessible.

 

[winnie]

On what basis do you think that the SER connector will need to be accessible?

 

[NEC Inspector]

I think you are not able to install the SER connector in the hole/wall. It needs to be accessible.

One method to install it is by clamping it to the cable, caulking it in, then threading it onto the box. Once installed, it does not need to be accessible. There is also possibility of installing it inside of some boxes instead of outside... but it usually wouldn't be fun...

Do they make snap-in connectors for SER that size?