Reflected ceiling plan for a backlit wardrobe in a Malleshwaram master: electrical rough-in placement and why it breaks the glass spec

The mirror sits 1.8 metres off the floor, frameless, 6mm thickness, and the LED cavity runs the full width behind it. But the electrical rough-in for the driver sits 300mm to the left of where the structural beam allows the cavity to sit. The mirror cannot float where the power reaches. This is the problem that arrives at site when nobody reads the reflected ceiling plan before the glass shop drawing is cut.

The Malleshwaram project: where the RCP met the wardrobe spec

A 3.2 by 4.1 metre master bedroom in Malleshwaram, built in 2022, faced this exact coordination failure. The architect had specified a full-width backlit wardrobe mirror—the kind that reads as a single glowing plane, not a lit object. The electrical consultant had placed a single rough-in for the LED driver in the ceiling void, positioned for convenience near the existing distribution board. The glass specification called for the cavity to sit 80mm behind the mirror, with a 50mm cavity depth for the LED strip and driver housing.

When the glass atelier received the shop drawing dimensions, the cavity placement forced a 280mm horizontal offset from where the electrical rough-in actually sat. The driver housing—a box roughly 120 by 80 by 40mm—could not fit in the cavity as dimensioned. The mirror spec broke. The architect had to choose: reposition the electrical rough-in (requiring a site visit and ceiling rework), or reposition the mirror (breaking the wardrobe alignment with the built-in storage below).

Reading the RCP before the glass shop drawing

What the RCP must show for a backlit wardrobe

The reflected ceiling plan is not a decoration. For any backlit mirror or cabinet, it must show: the outline of the cavity void, the position of any structural elements (beams, ducts, drop-soffit edges), the location of all electrical rough-ins (driver, transformer, junction boxes), and the height of the cavity opening. Most Bangalore projects skip this level of detail. The RCP arrives as a simple grid of downlights and a note that says "cavity as per architect's detail".

For the Malleshwaram project, the RCP showed the downlights and nothing else. The electrical rough-in existed only on the electrical single-line diagram, which the glass atelier never saw. This is the gap that breaks the spec.

The cavity depth and driver placement logic

A backlit mirror cavity needs 50 to 65mm of depth to house an LED strip (10mm profile) and a driver (typically 35 to 45mm in height when mounted vertically). If the driver sits horizontally, add another 15mm for cable routing. The mirror itself is 6mm. The mounting frame sits 8mm proud of the cavity rear. This totals 80mm minimum from the mirror face to the structural ceiling. If the structural ceiling is lower, or if the cavity cannot be positioned where the electrical rough-in sits, the entire assembly has to shift—and the mirror spec changes with it.

In Malleshwaram, the structural beam sat at 2.85 metres. The ceiling void was 350mm deep. The electrical rough-in was at 2.75 metres (100mm below the beam soffit). The cavity needed to sit at 2.77 metres to clear the rough-in box by 20mm (joint tolerance). This meant the mirror face sat at 2.69 metres—40mm lower than the original specification, which had assumed the cavity could sit anywhere in the void.

Why the glass spec breaks when electrical rough-in placement is wrong

The glass shop drawing specifies the mirror size, thickness, edge finish, and mounting frame position. It also specifies the cavity opening—the exact rectangular void into which the mirror and its backing frame fit. If the cavity opening moves, the mirror dimensions change. If the mirror dimensions change after the glass is cut, the piece becomes scrap.

The electrical rough-in placement determines the cavity location. The cavity location determines the mirror spec. In the Malleshwaram case, the rough-in placement was not coordinated with the wardrobe designer or the glass atelier. The electrical consultant placed it based on proximity to the distribution board, not based on the glass mounting requirement.

The result: the glass atelier received a shop drawing instruction that was impossible to build without either repositioning the electrical rough-in or accepting a mirror that was 40mm lower than designed. The architect chose to rework the electrical rough-in, which required a ceiling opening, a new conduit run, and a site supervision visit. This cost time and money that could have been avoided with a single RCP coordination meeting at the design stage.

How to coordinate the RCP with the glass wardrobe spec

The sequence: RCP first, then glass shop drawing

Before any glass shop drawing is issued, the RCP must be finalized and must show the electrical rough-in location. The glass atelier needs to see this to determine whether the cavity can sit in the intended location, or whether it needs to shift. Once the cavity location is fixed, the mirror dimensions are locked. Only then should the glass shop drawing be cut.

In practice, this means the wardrobe designer, the electrical consultant, and the glass atelier need to be in the same coordination loop. This is not standard on most Bangalore projects. The electrical consultant is often a separate entity, hired by the structural engineer or the MEP contractor, and they do not see the wardrobe specification until the rough-in is already in place.

The site dimensions that matter

When the glass atelier visits site to measure, they need to confirm: the exact position of the structural beam (to the millimetre), the depth of the ceiling void, the location of any existing conduits or boxes, and the position of the electrical rough-in box (including its height and depth). These measurements override the drawings. If the drawing shows the rough-in at 2.75 metres but it sits at 2.73 metres on site, the cavity location changes.

For the Malleshwaram project, a pre-shop-drawing site visit would have revealed the rough-in position and allowed the glass atelier to adjust the cavity location before the mirror was cut. This is standard practice for frameless shower enclosures—the site dimensions always come first. It should be standard for backlit wardrobes too.

Avoiding the Malleshwaram outcome on your project

Specify the RCP coordination requirement in the wardrobe brief. Ask the electrical consultant to show the rough-in location on the RCP before the design is finalized. Ask the glass atelier to visit site and confirm the cavity location before the shop drawing is cut. Build in a 2-week buffer for any repositioning.

If you are specifying a backlit wardrobe with an LED cavity, the cavity location is not flexible. It is determined by the electrical rough-in position and the structural ceiling height. The mirror spec flows from the cavity location. Get the RCP right, and the glass spec follows. Get it wrong, and you are cutting glass twice.

Patterns like Deco Noir or Golden Geometry are often specified for backlit installations because the geometry reads cleanly when lit from behind. But the geometry only reads as intended if the cavity is positioned correctly from the start.

Questions we get asked

Can the LED driver sit outside the cavity, in the ceiling void?

Yes, if the cavity is 50mm deep (LED strip only) and the driver sits loose in the void above it. This works if the void is accessible and if the junction box is within 1.5 metres of the driver. Most Bangalore projects prefer to keep the driver inside the cavity for thermal reasons—the LED runs cooler in a sealed space—and for serviceability. If the driver is loose in the void, it becomes hard to access during maintenance. For a 3.2 metre wide mirror, we recommend the driver inside the cavity.

What happens if the structural beam is lower than expected?

The cavity sits lower, and the mirror sits lower. This changes the wardrobe height and may affect the alignment with the built-in storage below. This is why the site measurement is non-negotiable. If the structural drawing shows 2.85 metres but site shows 2.80 metres, the wardrobe spec has to adjust. This should happen before the glass is cut, not after.

Does the electrical rough-in need to be inside the cavity footprint?

No. The rough-in can sit to the left or right of the cavity, as long as the conduit can reach the cavity opening without kinking. A 90-degree conduit bend takes up roughly 150mm of horizontal space. If the rough-in is 300mm away from the cavity, you need a longer conduit run, but it is buildable. The problem in Malleshwaram was that the rough-in sat 280mm away and the conduit routing was not planned. Specify the rough-in location on the RCP, and the conduit routing becomes a conversation, not a surprise.

Can you reposition the mirror after it is fitted?

No. The mirror is mounted to the cavity frame with silicone and structural adhesive. Repositioning breaks the seal and risks the mirror. If the cavity position is wrong, the mirror has to come out and a new one has to be cut and fitted. This is why the cavity location must be confirmed before the glass shop drawing is issued.

What is the typical lead time for a backlit wardrobe mirror after the shop drawing is approved?

Three weeks for cutting, edge finishing, and backing-frame fabrication. Two weeks for delivery and site fitting. If a repositioning is needed because of an RCP coordination failure, add another two weeks for the new shop drawing and cutting. Plan for coordination upfront and you save a month on site.

Coordinate the RCP with your electrical consultant and glass atelier before the shop drawing is cut. Talk to the atelier about your ceiling void depth, beam positions, and rough-in locations. A 30-minute coordination call at the design stage prevents a week of rework on site.