The Furnace Council

A Physics Comic in 9 Strips
LightCell Energy Lab • 60A Decision • 2026-03-28
The LightCell lab — monitors, Numark NS7III, ceramic bins on shelves
THE LAB — where the decision happens. Monitors, Numark, and furnaces just out of frame.
💥 Feynman First Principles
🎭 Oppenheimer Program Director
⚡ Shannon Circuit Wizard
🔥 Danielle Lab Commander
1
The Council Assembles
Feynman bursts in, Oppenheimer follows, Danielle looks up from monitors
FEYNMAN I heard there's a 60-amp question that needs answering! *chalk already in hand*
OPPENHEIMER Richard, you can't just burst into someone's ceramics lab and—
FEYNMAN Is that a Numark NS7? *reaches for turntable* You sinter AND you spin?
DANIELLE Welcome to LightCell. The furnaces are in the back. The question is on the whiteboard. Try not to touch the faders.
2
Feynman Does the Math
Feynman at whiteboard writing power calculations
FEYNMAN OK, first things first. Two circuits. Old one's 60 amps. New one's 60 amps. 220 volts each.
NEW CIRCUIT: 60A × 220V = 13,200W = 13.2 kW
minus ancillary (pumps, controls, cooling) ≈ 12A
HEATING AVAILABLE: 48A × 220V = 10.6 kW for elements
FEYNMAN The question isn't "how do we split 60 amps." The question is: how big a furnace can we feed? And do we want headroom, or do we want to run at the ragged edge?
DANIELLE We want a mondo furnace. An upgrade path. Flexibility.
FEYNMAN *grins* Then let's figure out what "mondo" means in kilowatts.
3
The 30/30 Trap
Oppenheimer diplomatic, Feynman horrified, Shannon with failing graph
OPPENHEIMER What about 30/30? Equal allocation. Democratic. Fair.
FEYNMAN Democracy is great for politics. Terrible for thermodynamics.
THE MATH Feynman grabs two small model furnaces and holds them up, one in each hand.
ON 30A: heating = 30 - 12 (ancillary) = 18A = 3.96 kW
LOSSES AT 1850°C IN H₂: 1.6–3.3 kW
NET RAMP POWER: 0.2–1.9 kW ← may never reach temperature!

Two furnaces at 30A each = two furnaces that can't do their job
SHANNON *holds up graph showing two declining lines that never reach 1850°C* In information theory we call this "dividing a channel below its minimum capacity." Both channels fail. You've transmitted zero information.
FEYNMAN You've built two very expensive space heaters.
4
The Program Director Speaks
Oppenheimer pointing at calendar, Danielle raises hand, Gantt chart
OPPENHEIMER Let me reframe this. You don't machine and sinter concurrently. You machine parts Monday and Tuesday. You sinter Wednesday. These are naturally sequential.
DANIELLE Right. The existing furnaces stay on the old 60A circuit. The new circuit is for expansion — the mondo furnace when we build it.
OPPENHEIMER Then why are we splitting anything? The three-way switch selects which equipment gets the full 60 amps. Position A: machining. Position B: existing furnaces if you need the extra circuit. Position C: the mondo furnace. Full power to each, just not simultaneously.
DANIELLE But what if I want a mondo furnace AND something else on position C? What if I want to keep an existing furnace warm while the big one ramps?
OPPENHEIMER *pauses* That's the real question. What does a mondo furnace actually need?
5
Shannon Draws the Circuit
Shannon with contactors and circuit diagram, others impressed
SHANNON A manual transfer switch forces you into three discrete operating points. But your actual demand is continuous. What you want is a contactor matrix.
                  60A MAIN
                    |
               [CT sensor]
                    |
         +----------+----------+
        [K1]      [K2]      [K3]
         |          |          |
    MACHINING   FURNACE A   FURNACE B

K1 exclusive — machining gets full 60A
K2+K3 both on — CT trips K3 if total > 55A
Cost: $500-950 total (contactors + CT + relay)
FEYNMAN That's... actually elegant. Automatic load shedding. No human has to remember to throw a switch at hour nine of a sinter run.
OPPENHEIMER At Los Alamos we learned: any procedure that depends on human memory during a 20-hour operation will eventually fail.
DANIELLE I like it, but the electrician is coming this week. What do I tell them TODAY?
6
The Hydrogen Problem
Furnace comparison - 40A dim vs 60A blazing, Danielle nodding
FEYNMAN Here's the kill shot. Hydrogen atmosphere has 10× the thermal conductivity of air. It doubles your steady-state losses.
MAX FURNACE VOLUME BY AMPERAGE (8hr ramp to 1850°C):

              VACUUM      H₂
30A         ~9L         ~5L     ← what you already have
40A        ~17L        ~11L    ← nice upgrade, not mondo
50A        ~26L        ~17L    ← genuinely mondo begins
60A        ~37L        ~25L    ← MAXIMUM MONDO
FEYNMAN A 40-amp mondo furnace in H₂ maxes out at 11 liters. That's not mondo. That's... *squints* ...medio.
DANIELLE *laughs* And we NEED H₂. Vacuum gets you 99.5-99.9% density. H₂ gets 99.7-99.95%. For translucent alumina, that last half percent is the whole game.
OPPENHEIMER So the atmosphere choice constrains the amperage choice. You cannot decide one without deciding the other.
7
The Cathedral of Watts
Furnace scale comparison from tiny to massive, team looking up in awe
NARRATOR Feynman draws four furnaces on the whiteboard, each larger than the last.
FEYNMAN At 30 amps, your furnace is *draws tiny box* this big. Same as what you have. At 40 amps *draws medium box* respectable, two-and-a-half times bigger. At 50 *draws large box* we're talking. And at 60...
NARRATOR He draws a furnace that takes up half the whiteboard.
FEYNMAN ...you get a furnace that could sinter a basketball. In hydrogen. With margin.
SHANNON The jump from 40 to 60 isn't linear. In H₂, you go from 11 liters to 25 liters. That's 2.3× the volume for 50% more amps. Diminishing returns haven't kicked in yet — you're still on the steep part of the curve.
DANIELLE So every amp I leave on the table is volume I can never get back.
FEYNMAN Now she's thinking like a physicist.
8
The Verdict
All three point at 60 on whiteboard, Danielle at monitors, group shot
NARRATOR All three turn to face Danielle. They point at the same number on the whiteboard.
FEYNMAN Give the mondo furnace everything. Position C equals 60A, no split. The existing furnaces already have their own 60A circuit. Don't kneecap your future at birth.
OPPENHEIMER The three-way switch selects which equipment gets power, not how to divide it. Position A: machining. Position B: existing furnaces. Position C: the mondo furnace. Full 60A each. Just not simultaneously.
SHANNON And when you're ready for the next level, replace the manual switch with a contactor matrix. $500-950. Automatic load shedding. The math doesn't negotiate.
DANIELLE *looks at the whiteboard, then at the furnaces in the back, then back at the team* 60A for the mondo. No split. With a contactor upgrade path.

THE FURNACE COUNCIL HAS SPOKEN

60
AMPS — NO SPLIT

Position A: machining • Position B: existing furnaces • Position C: MONDO FURNACE (full 60A)

9
The Best Power-to-Entertainment Ratio
Danielle grins at DJ controller, Feynman examines turntable, all laugh
DANIELLE *glances at the Numark NS7III* So 60 amps for the mondo, 60 amps for the existing furnaces, and the DJ controller just needs... a USB port.
FEYNMAN *already spinning a platter* THAT is the best power-to-entertainment ratio in this entire lab.
OPPENHEIMER I once directed a program that consumed the electrical output of a small city. Your 120 amps of ceramics furnaces are... modest, by comparison.
SHANNON But the information density per watt? *gestures at monitors showing code, DJ controller, furnace controls* This lab has the highest Shannon entropy per square meter of any workspace I've seen.
DANIELLE Alright, council adjourned. I'm calling the electrician. 60 amps, no split, position C for the mondo furnace. And someone get Feynman away from my turntables.
FEYNMAN *still scratching* You can't stop me. This requires fewer amps than your furnace and it's way more fun.

Technical Appendix: The Real Numbers

FURNACE VOLUME vs AMPERAGE at 1850°C (8hr ramp, 150mm insulation):

CIRCUIT   POWER     HEATING    VAC      H₂      PRACTICAL
—————————————————————————————————————
30A      6.6 kW    4.0 kW     ~9L      ~5L      1× current
40A      8.8 kW    6.2 kW    ~17L     ~11L     2-2.5×
50A     11.0 kW    8.4 kW    ~26L     ~17L     3-4× ← mondo starts
60A     13.2 kW   10.6 kW    ~37L     ~25L     4-5× MAXIMUM MONDO

KEY ASSUMPTIONS:
• Ancillary load (pumps, controls, cooling): ~12A fixed
• Insulation: 150mm composite (dense Al₂O₃ + fiberboard + microporous + blanket)
• Loss coefficient: ~5.4 kW/m² (vacuum), ~10.4 kW/m² (H₂)
• Thermal mass: ~333 × surface area (kg)
• Mo or W elements (MoSi₂ cannot operate in vacuum/H₂)