Options for installing sub-panel

Question

we are thinking about the best way to rewire our kitchen. It had 2 circuits when we moved in. We managed to add 2 circuits using an existing 3/4'' conduit that goes from the basement to our third floor apartment in the back hallway (see pictures below). However, we want to remodel the kitchen next year and our goal is to have at least 6 circuits in a kitchen with gas appliances. What are our best options and how much work do they require? We thought about three possibilities.

1. Stick with the EMT conduit and use multi-wire branch circuits to maximize the circuits we can get out of it. This is based on a previous suggestion from this forum.
2. Install 60A sub-panel in the 3rd floor using the EMT conduit with 3x #6 wires plus #8 wire for ground. Run 6/3 mc cable from basement junction box to main panel. A sub panel seems much more future proof. How do people feel about the #6 wires for 60A sub-panel. I read different things about that.
3. Install 60A sub-panel in the 3rd floor by replacing the EMT conduit with 4/3 mc cable that goes directly from main panel to sub-panel. We would remove the EMT and use the same holes for the mc cable. Maybe I am wrong but it seems relatively easy to run this cable.

In general, I like a sub-panel because it's more future proof and because it avoids the MWBC

Current conduit

The 3/4'' EMT conduit goes from the basement to a third floor junction box in the back hallway (about 30') and currently includes wires for 4 circuits (2 for kitchen, 2 for the living area).

Answer 1

The subpanel is the way to go. But make it big!

That is our #1 thing on panels - you want lots of spaces. Spaces are cheap, regrets because your panel is full are expensive. And that is a dinky little panel downstairs, you're not going to get much out of it, and I bet you're already double-stuffing that!

Of course you want a small "box size", but that can be had - you just have to look carefully. I have a small space" restriction and I'm looking at an 8-space QO panel barely larger than a sheet of paper. I might put 2 of them there, stacked above each other. You could drop straight down out of that junction box.

Or alternately, I don't know if anything is exiting the back of that junction box or if it's yours to rewire, but you have plenty of room for a full-size 30-40 space panel if the panel overlaps the 3/4" conduit. Have the conduit enter the bottom of the panel and exit the top. Any thru wires can passthru the panel.

You may think "A 60A feeder can only support eight 15A branch circuits, so why do I need more than 8 spaces?" Because of oversubscribing. You are vanishingly unlikely to use all 8 circuits at absolute limits at the same time, so it is normal/healthy to put several times that in breakers. This gives you the elbow room, for instance, to put the fridge on a dedicated circuit, non-GFCI so you don't have nuisance trips from unrelated circuits tripping the fridge. A fridge only draws 1 amp.

30 spaces fed from a 60A breaker is perfectly reasonable. Further, you could bump this to 125A by changing to a 1" pipe and #2 wire.

Conduit, oh yes!

All my work is in conduit and I can't recommend it more highly. Since it's EMT, you don't need to carry a ground wire. Given 3/4" conduit, #3 or #4 wire won't fit. But you can fit three #6 THHN wires in there, and have room for six #12 wires. That's only 3 more circuits (4 total) and you don't hit a crippling derate until 5. So that actually works quite nicely.

Or you could fit the three #6 along with three #10 for powering a dryer or another subpanel.

As far as the other three circuits also in this pipe, consider serving them out of this new subpanel, or another subpanel.

Too-low wires

I am concerned about that gaggle of NM cables running out of that panel. If the panel is low enough to be legal, then that bunch of NM is low enough to need physical protection from damage. The best physical protection I'm aware of is EMT conduit, but you can't put a bunch of Romex into a conduit; only 4 circuits per and for fill reasons you are better off switching to THHN wire.

I would try ThreePhaseEel's idea of flexible conduit. Regardless the point is you need to clean up your wiring so it is Code legal. You don't want to wait til the inspector sees this and suddenly wants everyone to fix theirs and there's contention for conduit space.

I suspect your landlord or council is not aware of the code violation here. The better thing would be for everyone to get together and fix it all.

Answer 2

Conduit is still your friend

Even though running rigid EMT back to the main panel from the basement junction box is basically impractical with all those other cables in the way, it is still possible to stay in conduit all the way back to the panel. How? Flexible conduit, that's how!

In particular, instead of running a cable (or cables) back to the panel, we replace all the existing cabling between the panel and the basement JB with 3/4" FMC, using a 90° fitting to come into the bottom of the basement JB as the EMT going up to the third floor leaves very little room to do anything else. We can then pull wires as-needed through that FMC: 3 6AWG THHN feeder wires, 4 14AWG THHNs for the existing 15A branch circuits, and a 10AWG or 8AWG bare ground will all fit through a 3/4" FMC, although it will be a tight pull, or you could pull wires for the MWBC route through it if you preferred, using a 12AWG bare ground from the panel to the basement JB. (The reason for the ground wire here is that FMC isn't allowed to be a grounding conductor by itself when more than 6' of it is used in a run.)

And yes, 6AWG is (more than) fine for a 60A subpanel

Anyone who is telling you that 6AWG is insufficient for 60A is full of hooey, as a 6AWG THHN copper wire landed on 75°C connectors and terminations (all modern distribution-equipment terminations are slash rated 60°C/75°C, which means that 110.14(C)(1)'s 60°C termination limit does not apply to them), and otherwise allowed to run at 75°C (as a wire in conduit is), is good for 65A. (In fact, thanks to the 240.4(B) round-up rule, you can use it for a 70A subpanel, even, although there's no point to that in your case.)

The only caveat for this is that the wire connectors used in the junction boxes must also be rated for 75°C usage. This is true of most mechanical set-screw (Polaris™ or equivalent) connectors, as well as of decent quality wire-nuts, but may not be true in all cases, so do check the specs on what you're using.

GO BIG OR GO HOME

When it comes to subpanel shopping, you will want to go big here. A 24-space or 30-space, 125A, main lug subpanel is not at all out of place here; if you wished to stick with GE, a TLM2412CCU (if you don't mind grey) or TLM2412CCUW (if "default electrical panel grey" would be a bothersome edition to the decor; the W suffix stands for a unit that's factory painted white) with a TGK32 ground bar field-fitted would be a good choice here.

As to getting wires from the third floor junction box into the subpanel, I would use a LB, accessed from the opposite side of the wall, and a 3/4" EMT run inside the stud bay to come down into the top of the panel. This will require a bit of patchwork, but gives you a 100% conduit installation while letting you flush mount the panel. Of course, if you'd rather have the panel surface mounted, that's an option as well, clear space permitting, and would let you simply run a length of 3/4" EMT down from the third floor junction box to the top of the panel.