SmartGlass wiring in a Hennur home office: why surface-mounted conduit beats in-wall when retrofit dimming is the spec

A 3.2-metre west-facing window in a Hennur home office catches afternoon glare at 2 p.m. precisely—the light hits the monitor, the desk becomes unusable, and the architect's specification for switchable glass arrives on site. But the electrical coordination hasn't been thought through: the dimming control needs to reach the glass panel, the existing wiring runs in-wall behind what is now drywall, and the site team is asking whether to chase new conduit through plaster or run it surface-mounted along the skirting. This decision, made in the field rather than at the drawing board, often determines whether the installation stays within tolerance and schedule, or becomes a coordination nightmare.

SmartGlass retrofit work in Bangalore's established residential micromarkets—Hennur, Sarjapur Road, HSR Layout, Indiranagar—sits at the intersection of existing building fabric and new control systems. The wiring is not incidental; it is part of the specification, and it must be called out in the shop drawing before drywall closes.

Why retrofit dimming wiring is not an afterthought

A switchable glass panel—whether Notte clear-to-blackout film or a full electrochromic pane—requires a 230V supply and a control circuit. In new construction, this runs as part of the electrical rough-in. In retrofit work, especially in home offices where the partition already exists and the wall cavity may be occupied by plumbing, HVAC ducting, or existing wiring, the path must be specified before any finishing work closes the wall.

Bangalore's post-tech-corridor housing stock—particularly in Hennur, Whitefield-adjacent areas, and Sarjapur Road developments—often features homes with walls already finished to plaster stage when the SmartGlass specification arrives. At that point, the electrical engineer and the interior architect must choose between two paths: chase new conduit through existing plaster (in-wall), or run it surface-mounted along the base or perimeter.

Surface-mounted conduit: when it reduces risk

Coordination and schedule certainty

Surface-mounted conduit is specified when the wall is already finished or when the risk of chasing through existing masonry is high. In Hennur and surrounding areas, where many homes sit on properties with granite-based foundations and older construction methods, chasing can hit unexpected obstacles—rebar, old electrical lines, moisture barriers—that delay the schedule and increase cost.

A surface-mounted run, by contrast, is visible, measurable, and can be coordinated with other trades before installation. The conduit diameter is typically 20 mm (for a single 4 mm² power cable and control pair), and the path is shown on the shop drawing with dimensions from the corner, skirting height, and termination points. The site team knows exactly what is coming and where it lands.

Electrical safety and inspection compliance

Surface-mounted conduit in rigid PVC or metal stays within Indian Standard IS 732 and local electrical inspection protocols. The run is inspectable—an inspector can trace the circuit from the switchboard to the glass panel without opening walls. In-wall chasing, by contrast, requires certification that the chase was done to depth (minimum 25 mm from the finished surface), that no existing services were damaged, and that the conduit is properly supported along its length. In retrofit homes where the wall composition is uncertain, surface-mounted eliminates that certification burden.

Bangalore's monsoon humidity (June through September, with ambient RH often above 75 percent) also favours surface-mounted conduit in older homes. In-wall conduit in a cavity with poor ventilation can trap condensation; surface-mounted runs stay exposed and dry faster.

When in-wall chasing still makes sense

In-wall conduit is the right choice when the wall is open—new partition construction, or a wall being rebuilt as part of the renovation. If the office is being stripped back to studs and refitted, the electrical rough-in should be coordinated with the glass installation from the start, and the conduit runs in-wall as standard practice.

In-wall is also preferred when the room design cannot accommodate visible conduit—a minimal or gallery-like aesthetic where every line matters. In those cases, the specification must be locked in before drywall closes, and the shop drawing must show the exact route, depth, and support spacing.

The cost difference between the two methods is often smaller than expected. Surface-mounted conduit and fittings cost slightly more per metre, but in-wall chasing requires a plasterer to make good, and the risk of rework is higher. On a 6-metre run in an existing wall, the real-world cost is often within 10–15 percent either way.

The shop drawing: what must be shown before drywall closes

Whether surface-mounted or in-wall, the electrical path must be documented in the shop drawing before the wall is finished. This drawing should show:

• Conduit diameter and material (rigid PVC 20 mm, or 16 mm if a single control wire)
• Start point (switchboard or existing outlet) with distance from corner and floor level
• Route: along skirting, up the wall, across the ceiling, or a combination—with dimensions
• Termination point at the glass panel, with height from floor and offset from the edge of the glass
• Support spacing: every 600 mm for horizontal runs, every 1000 mm for vertical (IS 732)
• Junction boxes at direction changes, with dimensions and accessibility confirmed
• Surface finish: conduit colour (typically grey or white to match trim), or concealment method if in-wall

This drawing is not decorative. It is the contract between the architect, the electrician, and the glass installer. Without it, the conduit is often run after drywall is up, routed around obstacles, and finished in a way that looks unintentional.

Dimming control placement and conduit length

The dimming switch or control module must sit within 2 metres of the glass panel, and the control circuit (typically a 2-core shielded cable, 0.5 mm²) runs alongside the power conduit. If the switch is wall-mounted, it sits at standard height (1.2 metres from floor), and the conduit rises from the skirting to the switch box, then continues to the glass. If the control is a wireless module (increasingly common in retrofit work), the power conduit still runs to a junction box near the glass, and the control signal travels via RF—eliminating the need for a separate control run.

On a typical Hennur home office—a 3.5 metre by 4 metre room with the glass panel on the west wall and the switchboard in an adjacent hallway—the surface-mounted conduit run might be 8–10 metres: from the switchboard, along the hallway skirting, around the corner into the office, up to switch height, and across to the glass. This is easily shown on an RCP (reflected ceiling plan) and a vertical section, and the site team can price and schedule it accurately.

Hard water, humidity, and conduit longevity in Bangalore

Bangalore's water TDS (total dissolved solids) sits at 200–300 ppm—moderately hard—and condensation in poorly ventilated spaces is common during monsoon. PVC conduit resists corrosion, but metal conduit (galvanised steel) can develop surface oxidation in humid conditions. If surface-mounted conduit is specified in a home office with high humidity or poor ventilation, PVC is the safer choice. If metal conduit is preferred for aesthetic reasons (brushed aluminium, for example), it should be powder-coated or specified with a corrosion-resistant finish.

The conduit itself is not the weak point; the termination points and junction boxes are. Ensure that all junction boxes are IP54-rated (dust and splash resistant) and that the conduit enters the box with a proper grommet or reducing bush. This detail is often missed on site.

Coordination with other systems: glass, dimming module, and power

The SmartGlass installation is part of a larger electrical and control ecosystem. Before the shop drawing is finalised, confirm:

• The glass panel specifications: voltage (230V AC, single-phase), power draw (typically 40–80 W for a 2 m² panel), and whether the control is hardwired or wireless
• The dimming module: if it requires a neutral wire (common in trailing-edge dimmers), ensure the conduit includes a neutral return—many retrofit installations forget this, and the dimmer fails
• The switchboard capacity: a new SmartGlass circuit should be on a dedicated 10 A breaker, with proper earthing (PE) routed alongside the power and control conductors
• Coordination with other finishes: if the surface-mounted conduit runs along the skirting, confirm its position relative to any dado rail, wall panelling, or other trim

In a Hennur home office where the glass panel is paired with a Studio partition system (if the office is a semi-enclosed space), the conduit path must clear the partition frame and any internal wiring the partition itself carries. This is a common clash point that a well-prepared shop drawing catches before site.

Questions we get asked

Can we run the SmartGlass power and control in the same conduit as other electrical circuits?

No. SmartGlass control circuits are low-voltage (typically 24 V DC from the dimming module) and must be segregated from mains power to prevent interference and to meet IS 732 safety rules. The power conduit (230 V supply) and the control conduit (24 V signal) should run parallel, but in separate tubes or separated within a multi-compartment conduit. If budget is tight, a single 25 mm conduit with a divider can house both, but it must be specified and inspected. Never bundle them without a barrier.

How do we hide the surface-mounted conduit if the aesthetic matters?

Surface-mounted conduit is visible by design, but it can be integrated into the room finish. Paint it to match the wall or trim (grey PVC painted white, for example). Route it along existing lines—skirting, picture rail, or the edge of a built-in shelving unit. In some Bangalore homes, a discrete surface-mounted conduit run along the skirting is less visually intrusive than a wall cavity that has been chased and made good with plaster that never quite matches the existing finish. The key is to show it on the drawings so the interior designer and architect can plan the visual hierarchy.

What is the typical cost difference between surface-mounted and in-wall conduit for a SmartGlass retrofit?

For a 10-metre run in an existing finished wall, surface-mounted rigid PVC conduit with fittings and labour typically costs 8,000–12,000 rupees. In-wall chasing, conduit, and plaster making-good typically costs 9,000–13,000 rupees. The real cost difference is in schedule risk: if chasing hits an obstacle (existing wiring, rebar, a moisture barrier), the cost and delay can double. Surface-mounted eliminates that risk, which is often worth more than the material saving.

Does the conduit need to be accessible after installation for maintenance or upgrades?

Yes. The junction boxes where the conduit terminates must be accessible—not buried behind furniture or trim. If the dimming module is wall-mounted, the switch box should be at standard height and not obscured. If the control is wireless and the module sits in a concealed location (inside a cabinet, for example), ensure the conduit entry is still accessible for future retermination. This is a detail often forgotten in retrofit work, and it causes problems when the system needs servicing.

Can we use flexible conduit instead of rigid for a surface-mounted run?

Flexible conduit (corrugated plastic or spiral-wound metal) is cheaper and easier to route around obstacles, but it is not recommended for surface-mounted runs longer than 2 metres or in areas where it might be damaged (high-traffic zones, near furniture edges). For a home office, rigid PVC is the standard. Flexible conduit is acceptable for short runs—from a junction box to the glass panel termination, for example—but the main run should be rigid and properly supported.

Commissioning the retrofit: what the site team needs to know

Once the conduit is installed and the electrician has terminated the cables, the SmartGlass system requires a commissioning visit. The dimming module is programmed, the control is tested at full range (clear to tinted, and back), and the power draw is verified. This is not the glass installer's responsibility alone; it requires the electrical contractor, the dimming system supplier, and the architect's representative on site together.

For home offices in Bangalore, where the space is often occupied immediately after handover, any rework due to wiring faults or dimming control issues is disruptive. A properly specified and documented conduit run, checked against the shop drawing before drywall closes, eliminates most of these problems.

If your Bangalore project includes SmartGlass retrofit work—whether a Hennur home office, a Sarjapur Road study, or a Koramangala workspace—the electrical specification is as important as the glass itself. Commission a shop drawing that shows the conduit path, the control logic, and the termination details. Talk to the atelier about your site constraints, and we will work with your electrical engineer to specify the right approach: surface-mounted for speed and certainty, or in-wall if the wall is open and the aesthetic demands it.