Key Numbers on a Lighting PlotEasyStagecraft Course · Tier 1B · Module 4 (Reading a Lighting Plot) · v1.0 · what every number written on a plot actually means

Why this matters. A lighting plot is covered in numbers. After this sheet, you'll know what every single one means: channels vs addresses vs dimmer numbers vs position numbers vs lens angles. Without this, the plot reads like noise. With it, every number is information.

The 6 number types you'll see on a plot

1. Channel number

Format: shown in parentheses next to fixture, e.g. (74) or as a circled number.

What it is: the console slot that controls this fixture. The number the LX op uses to fire the channel.

Range: 1 to 9999 (most consoles handle thousands).

Why it matters: when the SM calls "GO LX 47", the operator brings up channel 47. Multiple fixtures can share a channel (a wash group).

2. Dimmer number

Format: shown unparenthesised next to a conventional fixture, e.g. #12.

What it is: the physical dimmer channel controlling this fixture (relevant only for conventional fixtures — LED + movers don't use dimmers).

Range: 1 to ~96 in a school venue (24-channel rack × 1-4 racks).

Why it matters: if dimmer 3 fails, every fixture wired to dimmer 3 goes dark. Knowing dimmer assignment lets the LX op diagnose "channel 47 is dark" quickly: which dimmer? which breaker?

3. DMX address

Format: often shown as 001, 012, A:047 (where A = universe), or as a 3-digit number near the fixture.

What it is: the starting DMX channel the fixture listens on. LED + mover fixtures use 1-32 DMX channels each (the fixture's "footprint").

Range: 1-512 per universe; multiple universes for big rigs.

Why it matters: if two fixtures are accidentally on the same DMX address, they'll mirror each other. The fix: re-address one.

4. Position number (unit number)

Format: small number near the fixture, often inside a box, e.g. [6].

What it is: where on the bar the fixture sits. Counted from one end of the bar.

Range: 1 to however many fixtures are on the bar.

Why it matters: "Channel 47 is on LX2 pos 6" — gives the EWP operator the location during focus.

5. Lens angle (profile fixtures only)

Format: shown next to fixture, e.g. 26°, 36°, 50°.

What it is: the beam angle of a profile fixture (Source Four / Selecon Pacific). Narrow = far throw; wide = close-up.

Range: common school options are 19°, 26°, 36°, 50°.

Why it matters: wrong lens = wrong throw distance. FOH bars need 19°-26° (long throw); LX2 specials need 26°-36°; cyc-side units often 50°.

6. Wattage (conventional fixtures only)

Format: e.g. 650W, 1.2kW.

What it is: the lamp wattage. Affects how bright the fixture is + how much power it draws.

Range: 100W (PAR 38), 575W (Source Four), 650W or 1.2kW (Fresnels), 1.2kW (Followspots).

Why it matters: total wattage × number of fixtures = circuit demand. If dimmer rack capacity is 24A × 240V = 5760W per channel, and you've got 4× 1.2kW lamps on one channel = 4800W — under but tight. Plan circuit loading.

Other numbers you might see

What you seeWhat it is
Number next to a gel code (e.g. L201/2)Second sheet of L201 — used when the first one's heat-damaged or for tracking sheet usage.
Number on a focus chart e.g. A1, A2, B1Grid reference for focus zones on the stage floor. A1 = upstage-left quadrant, etc.
Number on a fixture for the gel cut #15References the gel cut list — the 15th cut on the list.
Number after a colon A:047"A" is the DMX universe; 047 is the address. Multi-universe rigs use this format.
Number next to a mover indicating 14 channelsThe fixture's DMX footprint (how many addresses it occupies).
Number near a power leg e.g. or P3Power phase indicator (3-phase distribution).
Number marked with + or Indicates a change in the latest revision — added (+) or removed (−).
Year + version on title block (e.g. v1.4 / 2026-05-02)Plot version + revision date.

A worked example · reading one fixture's annotations

Imagine a Source Four LED on the FOH bar marked as:

(15) #22 · S4 LED 26° · L201+L251 · DMX A:045 · pos 5

Decoded:

Cross-references — same fixture appears in 3 documents

DocumentHow the fixture is identified
Lighting plotSymbol + position label + channel + DMX address + lens + gel
Circuit list / Lamp scheduleRow per fixture: channel, position, unit#, fixture type, lens, gel, DMX address, purpose
Gel cut listGel code, count, position references

If you can identify a fixture in all three documents + they agree, you have a clean plot. If the numbers disagree between documents, something has been missed in a revision — flag it to the LD.

The "is this plot lockable?" 30-second test

Walk down this list with the plot in your hand:

  1. Pick any fixture. Can you identify channel + DMX address + position + gel + lens? Yes / No.
  2. Do the totals match the bill of materials? Yes / No.
  3. Is the version + date in the title block? Yes / No.
  4. Is the legend (symbol key) on the plot or attached? Yes / No.

If all four = Yes, the plot is lockable. If any = No, ask LD before signing off.