Why numbering is a system, not a label
A drawing number is a small piece of code that does a large amount of work. It tells the reader what the drawing is, which part of the project it belongs to, and how it relates to the others. When numbers are handed out ad hoc, the documentation becomes a pile of sheets that only their author can navigate.
Good numbering is boring and predictable. The same pattern appears on every drawing, so anyone can find a sheet from the number alone and can tell at a glance whether two drawings cover the same thing.
The investment is small — a short written procedure at the start of the job — and the return is a set that stays readable even after several rounds of changes.
What a drawing number should encode
A number does not need to carry everything, but the more useful it is, the less the reader has to guess. Most schemes encode a few of the following.
- Project or contract identifier, so sheets from different jobs never mix.
- Discipline code, which for electrical work sets the drawings apart from the other services.
- Drawing type, such as plan, single-line diagram, panel schedule or detail.
- Location or level, so the reader knows which part of the building the sheet covers.
- A running sequence number, unique within the set.
- A revision identifier, which ties the sheet to its place in the revision history.
The exact order matters less than consistency. Once the pattern is fixed for a project, it should not change halfway through, because every note elsewhere in the set that refers to a drawing will depend on it.
Building a scheme that scales
A workable scheme separates the parts of the number so that any one of them can grow without disturbing the rest. Grouping characters into blocks — project, discipline, type, location, sequence — makes the number easy to read and easy to sort.
For example, a number might read as a project code, an electrical discipline code, a type letter, a level digit and a sequence. The same pattern then covers single-line diagrams, floor plans and schedules, and a new drawing type simply takes a new type letter rather than breaking the pattern. Avoid reusing a number for a different drawing: a retired number should stay retired, which prevents confusion when an old copy reappears on site.
It also helps to keep the number short enough to write by hand and to read over the phone. A scheme that needs a lookup table to decode will not survive contact with a busy site, whereas a short, regular pattern is remembered after a day or two.
Revision control that survives reality
Numbering identifies a drawing; revision control identifies the version. Together they answer the only question that matters on site: is this the latest sheet?
Each revision should have an identifier, a date and a short description of what changed. A revised cloud on the drawing, matched by a note in the revision block, tells the reader exactly what moved. Without that, a reviewer has to compare two sheets line by line, which is slow and unreliable.
The revision history also acts as a record. When a question comes back months later about why a cable size changed, the revision note is the answer. Keep it short and factual, and keep the sequence continuous, so that a missing revision cannot be mistaken for one that never happened.
Issue status and the document set
Drawings are issued for different reasons, and the reader needs to know which. A common set of statuses distinguishes work in progress, review, tender and construction. The status should be printed on the sheet, because a drawing issued for review must never be mistaken for one issued for construction.
Alongside the status, the document set should stay coherent. A cable schedule, a panel schedule and the drawings it belongs to should all carry matching revision identifiers. If the drawings move to revision C but the schedule stays at revision A, the set has a defect even though each document is individually correct.
A simple register — one line per drawing, with its current revision, date and status — keeps the whole set visible in one place. When the register and the sheets agree, issuing a package becomes a routine task rather than a last-minute hunt.
Common pitfalls
Most numbering and revision problems come from a handful of habits.
- Renumbering drawings mid-project, which invalidates every cross-reference already circulated.
- Describing a revision as a general revamp instead of naming what changed.
- Updating a drawing without updating the schedules and the material list that depend on it.
- Relying on file names alone when the drawings will be printed and handled on site.
- Letting two people issue revisions from different copies of the same sheet.
- Issuing a set without a register, so nobody can say with certainty what the current revision is.
Keeping numbers and revisions in one place
Numbering and revision control are easier when the drawings, schedules and calculations share one source. GorkyCAD is a browser-based CAD system that produces the single-line diagram, plans, panels and cable schedule from a single electrical model, so a revision applied to the model flows through to the documents rather than being repeated sheet by sheet.
That single source also means the cable schedule and the material list cannot drift away from the drawings they belong to. You can open the editor in your browser free of charge and try the workflow on a real project, with no card required.
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FAQ
Should revision letters start at A?
Many offices reserve the first letter or number for the pre-issue stage and start formal revisions after that. What matters is that the rule is stated in the project's drawing procedure and applied consistently.
Can I reuse a retired drawing number?
Better not to. A number that has been withdrawn should stay withdrawn, so that an old copy found on site can still be recognised as superseded.
What should a revision description contain?
A short, specific note of what changed and where, using the clouded areas on the drawing as a reference. Avoid vague descriptions such as general updates.
Do schedules need revision control too?
Yes. Schedules are documents like any other, and they should carry the same revision identifiers as the drawings they accompany so that the set stays consistent.