Pre-installing electrical boxes on a modular housing line is a different problem from installing them on a single site build: the box has to work at station speed, has to be the same model every time a given wall type comes through, and has to arrive at the station in a way that matches how the line actually consumes material. Get those things right — station layout, model repeatability, and a fixing method suited to the process — and pre-installation becomes a predictable, repeatable step rather than a bottleneck.
Why factory pre-installation is a different problem than site installation
On a traditional site build, a box goes in once, by a tradesperson making individual judgement calls about position and fit. On a modular line, the same wall type recurs across every unit of a house type, at a pace set by the station’s takt time — and the box installation step has to keep up without individual judgement calls slowing it down. That means the position, the model, and the fixing method need to be decided once, upstream, and then repeated exactly, station after station, unit after unit.
This is a real enough distinction that dedicated “pre-fabricated house factory pre-installed” model variants exist alongside the general-purpose Concrete & Precast Boxes range, with a specific difference in conduit convention: pre-fabricated house factory lines typically use only Ø20 mm flexible tubes rather than Ø16 mm, so an inlet insert that a site installer might need isn’t required on the line-supply version. That’s the kind of detail that’s invisible until it isn’t — a line ordering the wrong inlet variant discovers it at the station, not on a spec sheet.
What matters for station layout
The box needs to be positioned so it doesn’t interfere with whatever else happens at that station — insulation, board fixing, other service runs — and so the operator’s motion to place it is short and repeatable. This is a layout question as much as a product question: the right box specified for the wrong position in the station sequence still slows the line down.
Why model repeatability matters more here than almost anywhere else
If a house type uses one box model in one wall position, every unit of that house type should use the same model, from the same supplier, for the life of that house type’s production run. A mid-run substitution — even to an apparently similar box — risks a dimensional or fixing mismatch that only shows up later, at final fit-out, after the wall is already closed. Keeping the same model for the duration of a house type’s production run is not a preference, it’s a risk-avoidance decision.
A real example of a station-friendly fixing method
For panel and board-built lines specifically (as opposed to wet-cast concrete), some models are built around a genuinely station-friendly fixing approach: dedicated box supports hold the box securely between the boards, and no further fixing of the box is needed at all — it’s simply placed in its final position when the top board layer is mounted. That’s about as close to zero added station time as a fixing method gets, and it’s worth confirming which models in a given range are built around it before assuming every model needs an active fixing step.
Packaging that matches how the line consumes material
A line doesn’t want a single bulk carton sitting at a station if that doesn’t match how the station actually draws material through a shift or batch. Packaging unit size is worth confirming with your supplier against your own line’s consumption pattern rather than assumed from a standard carton size — this is a conversation worth having per project, not a fixed answer.
A checklist for evaluating a supplier for line supply
- Confirm the exact model is available consistently for the full expected production run of the house type, not just for an initial order.
- Confirm packaging options against your line’s actual consumption pattern, not just the supplier’s standard carton size.
- Confirm the box’s fixing method suits your station’s process (fixing to stud/frame before board closure, for example) and doesn’t add a step the station wasn’t designed for.
- Get position and model requirements documented once per house type/wall type combination, and treat that documentation as the reference for every subsequent run — not something re-decided per batch.
- If a model needs to change mid-run for any reason, treat it as a new validation step, not a like-for-like swap.
What we do differently
We treat a line-supply relationship as a repeatability commitment, not a one-time order — the same model, the same packaging approach, for as long as your house type is in production. If your packaging or station requirement changes, tell us before the next batch, not after a line has already had to adapt around a mismatch.
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