Galley and Commercial Loads

The galleys are the largest sheddable load on the whole aeroplane — the headline target of the FCOM sentence the overview pinned as the system's design philosophy: "Commercial supply has secondary priority." Everything in this chapter that says "the galleys are shed on overload" comes home here. The decision logic was already drawn out elsewhere: ECMU and Contactor Management gives the three-scenario shedding table, and AC Distribution and Busbars gives the busbar segments (107XP / 208XP / 115XP). This article fills the two layers those leave open: the physical layer (the feeder power budget) and the operational layer (the full GALLEY pushbutton script, and the precise meaning of the "cycling-recovery" mechanism).

The reason the galleys matter out of all proportion to a coffee maker is arithmetic: a fully loaded galley network draws roughly as much power as an entire main generator. Once that number is fixed, the whole chapter's load-shedding logic stops being a rule to memorise and becomes something you can derive — which is where this article starts.

1. Scope and boundaries

By the end of this article you should be able to answer five questions:

1. What is the galley feeder power budget, and which chapter-wide rule does it explain?
2. How is the galley RCCB control chain organised across the two relays (2XA1 / 2XA2), and who signs for each group?
3. What is the logical relationship between the GALLEY and COMMERCIAL pushbuttons?
4. In the overload script, what is the electrical substance of the crew step (releasing the GALLEY pushbutton)?
5. When does "cycling the GALLEY pushbutton to recover" work, and when is it futile?

A boundary worth fixing at the outset. This article owns: the galley feeder architecture and power budget, the full GALLEY pushbutton logic, and the closure of the overload script. It reuses: the three-scenario shedding decision table (article 06), the five-step overload chain (article 02), and the RCCB as a component (article 14). The galley appliances themselves — ovens, water boilers — are an ATA 25 topic, not electrical.

2. Architecture — feeders and the power budget

2.1 Feeders and the power account

The galleys hang off the AC Main Distribution busbars through a set of three-phase feeder lines, each protected by its own Remote Control Circuit Breaker (RCCB):

"The galley supply three-phase feeder lines supply aircraft terminal blocks with 115/200 VAC, 400 Hz from the AC Main Distribution busbars 1XP and 2XP. The galleys (if installed) are electrically connected with cable lugs to the terminal blocks."

"Each RCCB controls and protects the power supply to a power feeder. The number of feeders and RCCBs depends on the number of installed galleys, the configuration of the galleys and their calculated electrical power consumption."

Per AMM 24-56-00. The second sentence carries a warning against memorising a fixed count: the number of feeders and RCCBs is configuration-dependent — it follows the galleys actually installed and their calculated power draw, not a fixed eight.

1XP  AC BUS 1 (left network) ──[2XA1]── feeders F1/F2/F3/F10 ──┐
                                                               ├─ terminal ─ cable
2XP  AC BUS 2 (right network)──[2XA2]── feeders F4/F5/F6 ──────┘  blocks   lugs ─► galleys
            each feeder passes through one RCCB
            (ECMU remote control + its own overload / short-circuit protection)
            RCCB 28 VDC control supply: DC Main Generation sub-busbars 103PP / 206PP
            galley supply: 115/200 VAC 400 Hz, three-phase

The power account — and this is where the chapter's whole shedding logic gets its physical root:

"Single Feeder Load Each feeder can supply a maximum load of 15 KVA. … All Feeder Loads All feeders can supply a maximum load of 105 KVA."

Per AMM 24-56-00. So a single feeder tops out at 15 kVA (the same in every configuration), while the total of all feeders is configuration-dependent: 105 kVA in the main passenger configuration, and 90 kVA in the freighter configuration (effectivity FSN 401-450). The installed RCCB set in the passenger configuration is "RCCB (1, 2, 3, 4, 5, 6 and 10)" — seven RCCBs (per AMM 24-26-00), so 7 × 15 kVA = 105 kVA, which is exactly the all-feeder figure. The absolute design ceiling — eight feeders at 15 kVA — would be 120 kVA, but no passenger configuration here installs the eighth.

That 105 kVA is the number to carry: a fully loaded galley network ≈ one IDG's rated output (115 kVA). The galleys, brewing at full tilt, eat almost a whole generator's worth of power. This makes the shedding logic inevitable rather than arbitrary — with a single generator carrying the whole network (a budget of about 115 kVA against the entire aircraft load), not shedding the galleys is simply impossible; once the APU generator joins and two 115 kVA sources are on line, the budget doubles and "shed nothing" (article 06, scenario 2) also becomes possible.

Left / right grouping (read from the ASM galley schematic; the AMM text does not give this feeder-to-bus mapping in words). The left group F1/F2/F3/F10 is drawn from 1XP (AC BUS 1) through relay 2XA1; the right group F4/F5/F6 from 2XP (AC BUS 2) through 2XA2.

[!warning]- The relay SIDE label on the schematic reads backwards

On the ASM schematic, the relay SIDE naming runs opposite to left/right intuition: 2XA1 is captioned "SIDE 2 GALLEY" yet it electrically governs 1XP / AC BUS 1 (the left network), while 2XA2 is captioned "SIDE 1 GALLEY" yet governs 2XP / AC BUS 2 (the right network). Read the grouping by electrical bus ownership (2XA1 → 1XP → left), not by the SIDE caption on the drawing.

2.2 The control chain — two ECMUs co-sign each group

The decisive verbatim is double signature, not "one relay owns a group, one ECMU crosses to the other side":

"The ECMU's manage the validity of the logics controlling the opening or closure of each Remote Control Circuit Breaker (RCCB) supplying the galleys: - the ECMU 1 and the ECMU 2 via the relay 2XA1 manage RCCB 1, 2, 3 and 10, - the ECMU 2 and the ECMU 1 via the relay 2XA2 manage RCCB 4, 5 and 6."

Per AMM 24-26-00. Three things read off this cleanly:

1. Each group of RCCBs is co-signed by both ECMUs — not owned by a single ECMU. The left group goes via 2XA1, the right via 2XA2; the relay is the collecting point for a group, not one ECMU's private channel.
2. The listing order reveals the lead. The left group (2XA1) lists ECMU 1 first; the right group (2XA2) lists ECMU 2 first — i.e. each group is led by its own-side ECMU, with the opposite-side ECMU as back-up. This runs the same direction as the contactor layer's "each ECMU manages its own side" — it is not "each ECMU manages the opposite side."
3. Because of the double signature, the loss of a single ECMU does not leave that group of galleys completely unmanaged; it does, however, produce the corresponding degradation set out in the single-ECMU-failure analysis in article 06.

Each RCCB's open/close logic is driven by a fixed set of inputs:

"Each RCCB (1, 2, 3, 4, 5, 6 and 10) and the relays (2XA1, 2XA2) have an associated control logic depending on the following inputs: - ELEC/GALLEY pushbutton switch, - GLC (1 and 2), APU GLC, EPC A, EPC B, - GCU (1 and 2) and APU GCU overload, - EXT PWR A and EXT PWR B overload."

Per AMM 24-26-00 — these are exactly the input side of the three-scenario table in article 06. Note that 24-26 gives only the hardware chain (pushbutton / relay / RCCB); the automatic shedding algorithm itself lives in 24-29:

"The galley automatic shedding is described in Ref. AMM D/O 24-29-00-00."

Per AMM 24-26-00. So when a fault question asks "which galleys go and in what order," the answer is computed in 24-29 (the Emergency Electrical Configuration / reconfiguration material), not here.

3. Working principle

3.1 The two pushbuttons — a logical AND

The galleys are powered only when both the GALLEY and the COMMERCIAL pushbuttons are on:

"When the pushbutton switch GALLEY and the pushbutton switch COMMERCIAL are in its on position, the galley supply RCCBs are energized and the contacts are closed. The galleys (if installed) are supplied with electrical power."

"When either the pushbutton switch GALLEY or the pushbutton switch COMMERCIAL is in its off position, the galley supply RCCBs are de-energized, all contacts are open and the galleys (if installed) are not supplied with electrical power."

Per AMM 24-56-00. So galley supply = GALLEY on AND COMMERCIAL on. The mechanism behind the "AND" is that the GALLEY function is gated by COMMERCIAL:

"The galley supply control pushbutton switch GALLEY controls directly the galley supply. This pushbutton switch is used: - To shed all the galley loads and - To reset the galley loads after an overload detection and an automatically shed by the ECMS. The function of the GALLEY pushbutton switch is only enabled when the AC Main Distribution pushbutton switch COMMERCIAL is in its on position."

Per AMM 24-56-00. So COMMERCIAL is the master switch and GALLEY is the sub-switch: with COMMERCIAL off, the GALLEY pushbutton does nothing at all, because the galleys have already gone with the whole commercial load. On the flight deck the GALLEY pushbutton carries AUTO / OFF positions with a FAULT legend (per FCOM DSC-24-20): in AUTO the galleys are normally supplied and the ECMU sheds them automatically on generator failure or overload; OFF sheds them all manually.

The two switches differ in their reach. Selecting GALLEY OFF touches the galleys plus two named penalties:

"OFF : All galleys are shed. Water/Waste (drain mast) ice protection is lost. The electrical supply of the heating floor panels is shed."

Per FCOM DSC-24-20. The floor-heating link is concrete in the AMM — it is fed by a discrete tapped off an RCCB auxiliary contact:

"The control unit(s) of the heated floor panel system is(are) supplied with a discrete 28 VDC signal from an auxiliary contact of the galley supply RCCB."

Per AMM 24-56-00. Selecting COMMERCIAL OFF reaches very much wider — the whole commercial family plus the galleys:

"OFF : The following equipment is shed: ‐ Galleys ‐ Cargo loading system ‐ Electrical service ‐ Escape slide lock mechanism ice protection ‐ Water/waste (drain mast) ice protection ‐ Lavatory and cabin lights ‐ Water heater ‐ In-seat power supply ‐ Passenger entertainment system."

Per FCOM DSC-24-20. (The busbar segmentation behind that list is treated in article 14.)

3.2 The 24-26 closure of the overload script

The five-step overload chain (article 02) runs identically for a GEN, APU GEN or EXT PWR overload. At the galley end it closes like this:

1. The GCU / GAPCU detects an overload → signal to the related ECMU → automatic shedding per the three-scenario table (article 06).
2. Shedding effective → no warning at all (the counter-intuitive point, confirmed again here — the SD shows only GALLEY SHED / GALLEY PARTIALLY SHED, with no MASTER CAUT).
3. Shedding not effective → the galley pushbutton FAULT legend, with the central warning set:

"- amber FAULT legend comes on on GALLEY pushbutton switch, - the MASTER CAUT accompanied by the single chime and the amber message GEN 1(GEN 2, APU GEN) overload, EXT PWR A overload) on the Engine/Warning Display (EWD) confirm the overload. The crew has to release the GALLEY pushbutton switch (white OFF legend comes on). This action results in opening relays 2XA1 and 2XA2 and then all the RCCB's. All the galleys are then shed. GALLEY SHED indication is displayed on the ELEC AC page on the SD."

Per AMM 24-26-00. The crew action — releasing the GALLEY pushbutton (white OFF legend) — takes the relay master switch path: it opens relays 2XA1 and 2XA2 together, which drops all the RCCBs at once. It does not go through the ECMU's per-RCCB logic. That is why the manual shed is more complete and quicker than the automatic shed (the speed/completeness comparison is integrative reasoning): the automatic shed is the ECMU computing the table segment by segment, while the manual shed is two master switches thrown directly.

3.3 Cycling — a conditional recovery

"NOTE: It is possible to try to recover only the galley shed because of overload conditions by cycling the GALLEY pushbutton switch: - the galleys are recovered if the overload condition does not continue, - the galleys are shed automatically if the overload condition continues."

Per AMM 24-26-00. FCOM states the same in pushbutton terms: "Switching OFF then AUTO resets the galleys which have been automatically shed by the ECMU" (per FCOM DSC-24-20). Three qualifiers must be read carefully:

1. Only an overload shed can be recovered. The part of the shed that follows the configuration (the "lost an IDG, no APU" portion in article 06) tracks the configuration — cycling does not bring it back while the configuration is unchanged.
2. It is a retry, not a force. If the overload still exists, the galleys are shed automatically again — the pushbutton cannot override the protection.
3. What it resets is the ECMU overload latch (one of the reset channels in article 06).

A practical reading: cycling once = asking the system "is there enough power now?" Bring the APU up or drop the load, and the answer becomes the galleys coming back.

3.4 The three display levels

On the ELEC AC page the galley message is shown one at a time by priority (per FCOM DSC-24-20 and the AMM SD indications): COMMERCIAL OFF (highest — the whole commercial family black, article 14) > GALLEY SHED (all galleys gone — manual OFF or automatic full shed) > GALLEY PARTIALLY SHED (a partial shed — the stepped "keep one feeder" state of article 06). Seeing PARTIALLY SHED tells you the system is sitting at an intermediate rung of the stepped shed — the next move is either recovery (the source has come back) or a full shed (the overload has worsened).

4. Operations and abnormals

4.1 Flight-deck scenarios

1. Cruise, lose GEN 2, APU not started, cabin reports "half the ovens are dead." Normal — the stepped shed has kept one feeder (article 06), and the SD shows GALLEY PARTIALLY SHED. The answer to the cabin: once the APU is up, one cycle of the GALLEY pushbutton brings them all back.
2. GEN OVERLOAD caution + GALLEY FAULT. The automatic shed did not succeed (step 3) — your action is to release the GALLEY pushbutton (the master switch sheds everything). To try to recover afterwards: first clear the overload source (start the APU / reduce load), then cycle the pushbutton to ask the system once.
3. The GALLEY OFF penalty account. Drain-mast ice protection is lost (worth recording in the decision on a long cruise in icing conditions) and floor heating is lost. These two are the penalties FCOM names specifically — galley shedding is "not just cold meals."
4. Ground, dual-source split supply, one side's galleys go dark. Work the ground rule from article 06 — which source overloaded and shed its own galleys. Per the AMM ground shedding table: EXT PWR A owns 4 / 5 / 6 / 10 + 208XP; EXT PWR B and the APU GEN own 1 / 2 / 3 + 107XP / 115XP (per AMM 24-29-00). Clear that source's load or change source, then cycle to recover.

A teaching image that holds all of this together: the galley is the gym in an office block. The whole building is fed 115 kW; the gym alone can draw 105. With mains normal (both generators) anyone can train; with half the building dark (one IDG lost) the management shuts the treadmills first and leaves only the changing-room lights on (stepped shed, keep feeder 2); when the power still isn't enough (overload alarm) the front desk asks everyone to leave (crew releases the GALLEY pushbutton = throw both master switches). Want to reopen? First check whether the generator truck has arrived (APU); if it has, swipe the door again (cycle the pushbutton) — and if the power still isn't there, swiping is futile, the management clears the room again at once.

4.2 Dispatch view (MEL) — all "go," the opposite pole to the static inverter

The galley and commercial loads are the first of the aeroplane's sheddable loads, and their dispatch tolerance is correspondingly the highest — all Category C:

• Galley supply system (24-26-01): Category C, 10-day repair interval, required quantity 0.
• Commercial supply system (24-26-02): Category C, installed 1 / required 0, placard yes.
• The overhead GALLEY / COMMERCIAL pushbutton FAULT lights (24-01-01): Category C.

Per the operator MEL. This is the exact opposite pole to the static inverter: the static inverter (24-28-01) carries repair interval "–", required 1 — must work (no-go), while the galley / commercial loads are Category C, required 0, fully dispatchable. One line fixes the chapter's whole dispatch philosophy: the closer a load sits to the survival floor (ESS TR / main batteries / static inverter), the more it is a no-go; the closer it sits to the "commercial, sheddable" end (galley / commercial), the more tolerant the MEL. This is exactly the overview's "Commercial supply has secondary priority" landing at the dispatch layer.

[!warning]- Common misconceptions — predict, then check

Read each statement, decide true or false, then check the truth in brackets.

1. "When the GALLEY pushbutton successfully sheds the galleys, the crew always gets some shed indication." — False. An effective shed gives no warning at all; the SD shows only GALLEY SHED / GALLEY PARTIALLY SHED (§3.2). Only an ineffective shed raises the amber GALLEY FAULT + MASTER CAUT.
2. "GALLEY OFF and COMMERCIAL OFF are just two switches that cut the galleys — same effect." — False. They are a logical AND, but their reach differs: GALLEY OFF touches the galleys (plus drain-mast ice protection and floor heating); COMMERCIAL OFF touches the whole commercial family of sub-busbars plus the galleys (§3.1).
3. "Once the galleys are shed, cycling the GALLEY pushbutton always calls them back." — Conditional. Cycling recovers only an overload shed: it recovers if the overload has cleared, and sheds again at once if it continues (the pushbutton cannot override the protection). A configuration shed ("lost IDG, no APU") is not recovered by cycling while the configuration is unchanged (§3.3).
4. "The ECMU's automatic shed is more complete than the crew manually releasing the GALLEY pushbutton." — False. The reverse: the manual pushbutton takes the relay master-switch path (2XA1 + 2XA2 thrown together, bypassing the ECMU's segment-by-segment logic), so it is more complete and quicker; the automatic shed is the one that computes segment by segment (§3.2).
5. "Once the APU generator is on line, you still have to shed the galleys to free up power." — False. A fully loaded galley is 105 kVA ≈ one IDG's 115 kVA; a single source carrying the whole network has insufficient budget and must shed, but once the APU GEN joins, two 115 kVA sources are on line, the budget doubles and "shed nothing" holds (§2.1, article 06, scenario 2).

Self-test

[!note]- Q1. What is the galley power account, and which chapter-wide rule does it explain?

A single feeder maxes out at 15 kVA; all feeders total 105 kVA in the passenger configuration (90 kVA in the freighter configuration, FSN 401-450) — close to one IDG's 115 kVA rating. This explains why a single generator carrying the whole network must shed the galleys (insufficient budget), why the galleys are fully held once the APU joins (budget doubled), and why the galleys are the headline "secondary priority" commercial load. The seven installed RCCBs (1, 2, 3, 4, 5, 6, 10) × 15 kVA = 105 kVA, consistent with the all-feeder figure.

[!note]- Q2. How is the galley control chain organised, and who signs for each group?

Left group RCCB 1 / 2 / 3 / 10 via relay 2XA1; right group RCCB 4 / 5 / 6 via relay 2XA2. Both ECMUs co-sign each group — the own-side ECMU leads (2XA1 lists ECMU 1 first, 2XA2 lists ECMU 2 first), the opposite-side ECMU backs up. It is not "one ECMU manages the opposite group." Each RCCB's logic takes the inputs: GALLEY pb, GLC 1/2, APU GLC, EPC A/B, GCU 1/2 + APU GCU overload, EXT PWR A/B overload. The automatic shedding algorithm itself lives in 24-29.

[!note]- Q3. What is the relationship between the GALLEY and COMMERCIAL pushbuttons?

A logical AND — both must be on for galley power, either off sheds them all. COMMERCIAL is the master (the GALLEY function is only enabled with COMMERCIAL on); GALLEY is the sub-switch. Their reach differs: GALLEY OFF touches the galleys + drain-mast ice protection + floor heating; COMMERCIAL OFF touches the whole commercial family of sub-busbars + the galleys.

[!note]- Q4. What is the electrical substance of the crew releasing the GALLEY pushbutton?

It directly opens the governing relays 2XA1 + 2XA2 → all galley RCCBs de-energise and open → all galleys shed. This is the relay master-switch path, bypassing the ECMU's segment-by-segment logic, so it is more complete and quicker than the automatic shed. The SD shows GALLEY SHED.

[!note]- Q5. What are the bounds of the cycling retry?

It works only for galleys shed by an overload condition, and it is a conditional retry — recovered if the overload has cleared, shed again at once if it continues (the pushbutton cannot override the protection). A configuration shed (lost IDG, no APU) is not recovered by cycling; cycling becomes meaningful only after the configuration recovers (APU comes on line). What it resets is the ECMU overload latch.

Key takeaways

References

Per AMM 24-56-00 D/O (galley three-phase feeders from 1XP/2XP, 115/200 VAC 400 Hz; RCCB controls and protects each feeder, feeder/RCCB count configuration-dependent; single feeder 15 kVA / all feeders 105 kVA passenger and 90 kVA freighter; RCCB 28 VDC control supply from sub-busbars 103PP/206PP; the two-pushbutton AND and the GALLEY-enabled-by-COMMERCIAL gate; heated floor panel discrete from an RCCB auxiliary contact); AMM 24-26-00 D/O (the two-ECMU double-signature management via 2XA1/2XA2, the installed RCCB set 1/2/3/4/5/6/10 and the per-RCCB logic inputs, the automatic shedding pointer to 24-29, the overload-script crew step opening relays 2XA1+2XA2 and the cycling NOTE); AMM 24-29-00 D/O (the in-flight and ground galley/commercial shedding tables, EXT PWR A vs EXT PWR B/APU side ownership); FCOM DSC-24-20 (GALLEY pushbutton AUTO/OFF/FAULT and the OFF penalties — drain-mast ice protection, floor heating; the COMMERCIAL OFF shed list; the SD GALLEY SHED / GALLEY PARTIALLY SHED / COMMERCIAL OFF indications); the operator MEL 24-26-01 / 24-26-02 / 24-01-01 (galley and commercial all Category C, required 0) and 24-28-01 (static inverter no-go, for contrast). The left/right feeder-to-bus mapping and the inverted relay SIDE caption are read from the ASM galley schematic; the "105 kVA ≈ 115 kVA" reading of why shedding is necessary, the "master switch vs segment-by-segment" speed comparison, the "closer to the survival floor = more no-go" dispatch philosophy, and the office-block-gym analogy are integrative syntheses of the above and contain no facts from outside the library.

Independent study material, not an Airbus publication. Refer to current operator FCOM, FCTM, and QRH for operational use.