Transition from flush mount CSED to surface mount conduit in a 2x4 exterior wall

[BackCountry]

We often encounter flush mount combination service entrance device (CSED) panels like in the attached photo.

When adding additional equipment, I have never been able to find a code compliant way to transition from the flush panel to an exterior LB, gutter, or NEMA 3R box. Typically, we cannot access the back side of the panel (interior living space) and we often need to pull in more than just a feeder (if we did, NM cable would be fine).

When relocating 10 or 14 #12 and #14 branch circuits, for example, there’s simply no way to fit that much NM into the bottom or top of the flush mount panel.

What we usually do, is install an LB (like in the photo) with a chase nipple and bushing at the flush mount panel. We then run THWN for all circuits and wrap the 6-8” section of “free air” conductors running inside the wall from the LB to the top or bottom of the panel. We seal the penetration with an appropriate sealant.

I don’t like it, but there’s no fitting that can make that tight of a bend radius. Nor will flex conduit make it, LFMC, or anything else I’ve found.

That don’t make flush mount NEMA 3R boxes.

Does anyone have a better solution?

 

[LarryFine]

Make the hole for the LB high enough above the panel for the FMC to be able to be shaped like a question mark inside the wall, or used cables (not NM).

You should not be running "wrapped" individual conductors in the wall without a raceway.

Or, cut the new panel into the wall in an adjacent stud space and join the two panels with a nipple or two through holes hole-sawed through the stud.

 

[BackCountry]

Make the hole for the LB high enough above the panel for the FMC to be able to be shaped like a question mark. You should not be running "wrapped" individual conductors in the wall.

Unfortunately, the bend radius in a 2x4 wall is too tight for anything beyond 3/4” FMC — we can’t get behind the panel most of the time, so we’re limited to that 3.5” of space to make the bend. We often need 2” conduit for the number of conductors. Even if we tried to split it up, there’s not enough space.

 

[tom baker]

Have a custom nema 3R fabricated that would be 8 inches deep and the width of your exterior panel. This wireway would extend into the wall and out of the wall above the new exterior panel. nipple between the wire way inside the wall and your existing combination service entrance panel. have the wire way the same width as your new exterior panel. A few trim boards around the wire way opening and the new panel and you’ll have a very nice looking insulation.

 

[BackCountry]

Have a custom nema 3R fabricated that would be 8 inches deep and the width of your exterior panel. This wireway would extend into the wall and out of the wall above the new exterior panel. nipple between the wire way inside the wall and your existing combination service entrance panel. have the wire way the same width as your new exterior panel. A few trim boards around the wire way opening and the new panel and you’ll have a very nice looking insulation.

Hey Tom,

I agree: I’ve tried that before with a 12x12x8 3R box, and we drilled holes in the sides to secure it to the studs and some blocking to bring in the sides of the stud bay to 12”. We used peel and stick flashing tape to lap it onto the sides of the box and trim boards around it to hide the flashing. It worked out ok, but that house had wood siding. The secondary problem was that there are almost always branch circuits on the top and bottom of these panels, so we had to disconnect those and reroute them through the box. It works, but in the stucco world I worry about water long term without having flanges. I suppose we could buy some flange kits for a convertible panel and adapt them. I was hoping for a simpler out of the box solution.

One thing I’ve never tried is using a rigid 2” close elbow, with a built in hub. I suppose I could drill a hole the size of the elbow, double lock ring it inside the wall to the top or bottom of the CSED, and then nipple out to an LB. It might work, the specs I looked up show them as 4” x 4” for a 2” trade size. I usually only do 2” on these installations, so as long as we could find some space for a KO that large it would work.

Even a semi flush panel is tough, the largest KO’s on those are usually 1” and that’s if the stucco or siding contractor didn’t build it out too much to cover them up partially.

If we’re doing an ESS job, it’s not uncommon to need to bring over 10-20 Branch circuits and #1 or #2 feeders plus a ground. I try to get into a 3R wireway as soon as I can, but again: that transition from inside the wall to surface is a challenge.

 

[tom baker]

I am without code book, and am not sure if WWs have to be listed. The WW I was suggesting would go on right side of service panel.

 

[letgomywago]

I have a solution but you won't like it

UF cable

Other option is to 45 ENT and have the pvc LB be at a 45. It's ugly but way more compliant than what you've been doing.

Finally cut in a slot and use 22 bends on the conduit and then caulk really good this is ugly too but if you need EMT for whatever reason this works with it. I hate doing this so I don't suggest doing it.