What a tender GA has to show, and what it doesn't
A tender general arrangement (GA) shows the client that the equipment you are offering fits, where each item goes, how it is reached and how cables get to it. It carries the overall footprint and height of each item, its position with key dimensions, the access and maintenance clearances, the cable entry and trench routes, any future space, and equipment references that match the single line diagram. It leaves out what a fabrication drawing needs: internal busbar arrangements, sheet metal details, fixings, tolerances and a full bill of materials.
The line matters because a tender GA is read twice. The evaluator reads it to decide whether your offer fits the room and meets the specification, and later, if the submission becomes a contract document, someone reads it to decide what you promised. Elora Grid drafts a first tender GA from the specification and the equipment list, in your title block and with a 3D view to check clearances; your engineers decide what goes out with the bid.
What is a tender GA for?
Two readers, with different questions. The client's evaluator wants to see that the switchboard, the transformer or the enclosure fits the space, keeps the clearances the specification asks for and can be maintained once installed. Your own team wants the quantities the drawing settles: the room size, the plinths, the trench length, the cable entry, the spare tiers.
Neither reader needs to know how the equipment is built inside. At tender the supplier is often not chosen yet, so the internal arrangement is not yours to state.
What must a tender GA show?
The envelope and the position of every item. That means the footprint and height of each board, transformer or enclosure, drawn from the quote you are actually pricing, and dimensioned to the walls, the doors and the neighbouring equipment. Add the access and maintenance space in front of and behind each item, including the draw-out space for withdrawable breakers and the swing of every door. AS/NZS 3000 sets minimum access and egress around switchboards in Australia, and the specification often adds more.
Then the connections and the future. Show whether cables enter from the top or the bottom, where the trench or tray runs and where it penetrates a wall. Mark the spare floor for future tiers if the single line diagram shows spare ways. On a generator enclosure the same logic gives the overall envelope, the access doors, the inlet and discharge louvres, the exhaust outlet, the base tank and the lifting points.
What should stay off it?
Anything you cannot stand behind until a supplier is appointed and the design is developed. Internal busbar layouts, sheet metal folds, gland plate details, fixing schedules, material gauges and tolerances all belong on fabrication and shop drawings. So does the detailed wiring inside a panel, which lives on the wiring diagram.
Leaving them off is not a shortcut. Each detail you draw at tender is one more thing the client can later point to, drawn before anyone had the information to get it right.
Why does the difference matter commercially?
Because a dimension on a tender GA reads as a promise. Say the GA shows 1,200 mm in front of a switchboard, and the board you end up buying needs 1,500 mm to draw out its breakers. If the room was sized from your drawing, there is no variation to claim; the fix is yours.
Protect the drawing with words. Mark it as issued for tender, state equipment dimensions as nominal and subject to the selected supplier, and keep a notes block for the assumptions: the supplier quote the envelope came from, the cable entry assumed, the clearances applied. Check how the contract treats the tender submission against the order of precedence, so you know whether the GA can outrank the specification.
How do you check a tender GA before it goes out?
Lay it beside the single line diagram first. Every panel, transformer and enclosure on the SLD should appear on the GA with the same reference, and every spare way should have somewhere to go. Then read it against the specification for clearances, ingress protection, cable entry and any layout the client has prescribed.
Last, check the envelopes against the quotes you are pricing rather than a catalogue drawing from a different make. Elora Grid compares the GA with the SLD and the specification and lists each mismatch with the drawing and clause it came from; whether the drawing is ready to issue is your engineer's call.
Tender GA against fabrication drawing
| Tender GA | Fabrication drawing | |
|---|---|---|
| Purpose | Show the offer fits and can be accessed | Tell a workshop how to build it |
| Dimensions | Envelopes, positions and clearances | Every part, with tolerances |
| Internal detail | None, or outline only | Busbars, folds, fixings, materials |
| Drawn from | The specification and supplier quotes | The appointed supplier's design |
| When | Before award | After award, often after design review |
| What it commits you to | Fit, access and the stated assumptions | The detailed design |
- 01Start from the quotes you are pricing. Take each envelope from the supplier quote, not a catalogue of another make.
- 02Place every SLD item with its reference. Same references as the single line diagram, spare ways included.
- 03Draw the access and draw-out space. Front, rear and door swing, against AS/NZS 3000 and the specification.
- 04Show cable entry, trenches and penetrations. Top or bottom entry, routes and where they cross walls.
- 05Add the notes block. Issued for tender, nominal dimensions, the quotes and clearances assumed.
- 06Check it against the SLD and the specification. Every mismatch is a fix before issue or a qualification in the bid.
Common questions
What is a tender general arrangement drawing?
A tender general arrangement drawing shows the physical layout of the equipment offered in a bid: the footprint and height of each item, its position in the room or on the site, the access and maintenance clearances, the cable entry and any future space. It shows the client the offer fits and can be maintained, and it carries no fabrication detail.
Is a tender GA a contract document?
It can become one. If the contract incorporates the tender submission, the GA you submitted may sit among the documents you are held to, so its dimensions read as commitments. Check how the contract treats the submission and the order of precedence, mark the drawing as issued for tender, and state envelopes as nominal and subject to the selected supplier.
How much detail should a tender GA have?
Enough to show fit, access and connection, and no more. Dimension each envelope and its position, the clearances and the cable entry. Leave internal busbar arrangements, sheet metal details, fixings and tolerances for the fabrication drawings, which follow the appointed supplier's design. Detail drawn before that point is detail you may be asked to honour.
Can Elora Grid draft a tender GA?
It drafts a first general arrangement from the specification and the equipment list, in your title block and drawing standards, with a 3D model to check clearances and access, and it lists any mismatch with the single line diagram. The drawing comes out as DWG, DXF and PDF for your drafters to edit, and your engineers decide what is issued with the bid.