Licensed Electricians, I have a question...

[Dana67Dart]

I have Romex that I need to extend, not practical to run new point to point. I need to go around a new air inlet to my machine room. The electrician who ran the original wires, 25 years ago, took the path of least resistance rather than going thru floor joists went under them in the unfinished machine room.

I have 4 #14/2 and 1 #12/2

My plan is to cut each run about mid run. Add a J box to left and right ends of the runs then add new runs between the J boxes. In each J box will be 1 Romex in and 1 Romex out per run, so 10 Romex will enter each J box. There will not be any switches or other devices in each J box only the wires and wire nuts.

So the biggest question is What size J-Box do I need?

By my calculations I need about 42 cu in. Does that calculate out correctly? BTW US, single family, residential home, in my area owners can do their own work.

Thanks all

 

[1MeanA]

I’m not an electrician but have done a bit of wiring. How many wires are running to this machine room? Id think about running one cable to a sub panel if you can put it in a location that your electrical authority approves of.

 

[Elmo65]

4 11/16.

 

[Dana67Dart]

I’m not an electrician but have done a bit of wiring. How many wires are running to this machine room? Id think about running one cable to a sub panel if you can put it in a location that your electrical authority approves of

What it is is ceiling lights, outlets and switch legs. All coming from finished space one end of the room to the other, then going back into the finished space.

So a sub panel is not warranted. But thanks for the thought.

 

[grjammer]

What you are describing sounds like a duct has to be run across a run of wires that are stapled to the bottom of joists and you don't want them to be pinched under the duct when the duct is sitting flat on the joists.
I would just notch the 5 runs into the "affected" joists and use a nail plate on each notch. Hard to say it will work for sure unless I could see the installation.

 

[YY1]

You are wire nutting four #14 and one #12 together?

That's quite a bit.

Do yourself a favor and get 5" "deep" boxes.

Why cram stuff in when you don't have to.

 

[CFD244]

 

[MiradaMegaCab]

The OP’s 42 CI estimate is correct, or close based on box fill of 2CI for #14 and 2.25CI for #12’s.
Perhaps use a 3 gang box as there’s 5 Knockouts on each side making cable referencing easy, in and out splicing together without the chance of getting wires confused …..

60CI

 

[Garrett Ellison]

The above option looks good. Depending on how much room you have to put them, I would recommend a pair of indoor pull boxes. It doesn't hurt to go above code standards and give your self some extra room to work.
Wiegmann SC060604 SC-Series NEMA 1 Screw Cover Wallmount Pull Box with Knockouts, Painted Steel, 6" x 6" x 4",Gray - Amazon.com

 

[Dana67Dart]

Hard to say it will work for sure unless I could see the installation.

North is to the right in this photo


Cut wires near black circle
terminate in the J box
Splice each run to a new run and head each run south following the blue

I need to insulate this duct, 10 deg F incoming air and 20% humidity in the machine room equals ice on the makeup air inlet duct. Last winter I put heater tape on it with a thermostat switch and it worked OK ish.

The machine room actually stays well above freezing.

Other end of the run.

Cut wires near black circle
terminate in the J box
terminate each run to the run from the other J box (blue)

(They did such a great job with the insulation 20 years ago!)

If I put the J box where indicated I'll also put the splice in the 1 gang box in the new box so that box will need to be larger. But either way I will not be hiding the 1 gang box.

 

[Dana67Dart]

You are wire nutting four #14 and one #12 together?

No just extending the runs, so 1 #14/2 coming in gets wire nutted to 1 #14/2 going out, times 4, plus one 1 #12/2 coming in gets wire nutted to 1 #12/2 going out.

 

[diymirage]

 

[Dana67Dart]

Now That's Funny!

 

[ProjectBazza]

Couldn't you just use a readily available PVC j-box like this?

Graingers, Home Depot, Lowes, Menards....

 

[Dana67Dart]

Couldn't you just use a readily available PVC j-box like this?

Yep but it has to be the correct inside volume.

That's where I'm unsure

 

[1MeanA]

Around here you can buy a code book that can really help. I know the codes say that jbs cant be concealed and must be accessible. Somebody put one behind a wall in my old house years ago. Its a problem as i believe there is a loose connection that needs to be fixed…a Christmas job. The circuit is not being used right now.

 

[Dana67Dart]

Around here you can buy a code book that can really help

Yep but interpreting it is where I have issues


Like 1 #14 needs 2 cu in. But all the grounds count as 2 cu in or something like that.

Do wire nuts count?

if the box has knockouts and you use a clamp to attach the Romex to the box?

If the box has built in clamps do you have to account for them?


Confused Im So Confused GIF - Confused Im So Confused So Confused - Discover & Share GIFs

 

[1MeanA]

If you're going to get it inspected you could do what I did last time I had an electrical question that I couldn't figure out (power to new garage…how to redo the service). I went down to the electrical inspection office and asked one of the inspectors working the front desk. He told me exactly how it must be done. It took the doubt out of it and even saved me money.

 

[Elmo65]

Heres a suggesrton. Use a single box for each connection. There will be no confusion that way.

 

[Garrett Ellison]

When it comes to JB volume, the code requirement is the basement of what it has to be. Putting in a minimal size junction box always turns into more work than its worth. Always good to have extra volume to stuff everything into. You'll generally be joining all the grounds together inside of each box and using a pigtail of #14 from the connection to ground the box with. Romex/Nomex clamps are generally required when passing Romex/Nomex through an electrical box.

 

[Garrett Ellison]

That’s why I recommended the pull box originally. If you have adequate space for access through the front when mounting it, it makes the whole affair simpler to deal with and usually puts your work above code requirement.

 

[YY1]

Yep but it has to be the correct inside volume.

That's where I'm unsure

Err on the "too large" side.

Don't overcomplicate it.

 

[MiradaMegaCab]

60CI