SmartGlass wiring conduit placement through a Hennur partition: why surface-mounted beats in-wall when retrofit dimming breaks the tint uniformity spec

Walk into a Whitefield office retrofit with a new Studio partition that disappears on demand and watch the dimming cycle. If the conduit runs inside the partition frame—threaded through cavity, hidden, neat—the relay will lag by 2 to 4 seconds, and the tint will band horizontally across the glass. The architect specified 0.8 seconds stem-to-opaque. The client sees a stripe. This is not a defect in the glass. It is a conduit placement problem.

Retrofit SmartGlass wiring in Bangalore's monsoon season (June through September) meets a specific adversary: humidity trapped inside a partition cavity will slow the electrochromic response, breaking the tint uniformity the specification promised. Surface-mounted conduit—routed along the frame edge, visible, finished in powder-coat or brushed aluminium—eliminates that pocket and delivers the cycle time and colour field the glass was designed to produce.

Why in-wall conduit creates humidity pockets that delay relay response

A partition cavity is a semi-sealed box. When you thread power and control conduit through it, you create a microclimate. Bangalore's Cauvery water carries a TDS of 200 to 300 ppm—hard, mineral-laden. During monsoon, relative humidity in an unventilated partition cavity can reach 75 to 85 percent. The relay and driver electronics in a SmartGlass system respond to voltage and current; they are not tolerant of condensation or slow moisture migration across circuit board traces.

The electrochromic layer itself—the film that darkens when energised—requires a clean electrical path. When humidity enters the cavity and settles on the relay contacts or the driver board, the voltage delivery becomes intermittent. The glass receives power in stutters rather than a clean pulse. The result is uneven darkening: the top of the partition dims first, the middle lags, the bottom catches up two seconds later. The architect's spec—tint uniformity to within 5 percent across the field—is broken.

In retrofit work, where the partition is already framed and the cavity is closed, extracting conduit becomes a site issue. Architects often specify in-wall routing to avoid a visible raceway. The cost is paid in the dimming cycle.

The surface-mounted conduit specification: why it preserves tint uniformity

Surface-mounted conduit—routed along the outside face of the partition frame, secured with stainless-steel clips at 400mm centres, finished to match the frame—delivers power and control signals in a dry, open environment. There is no cavity, no trapped air, no humidity pocket. The relay sees clean voltage every time. The glass dims uniformly across the entire field in 0.8 to 1.2 seconds, stem-to-opaque, as specified.

The conduit itself is 16mm diameter, powder-coated in a colour matched to the frame finish (natural anodised, brushed stainless, or powder-coat). At 400mm spacing, the clips are barely visible from a normal viewing distance. From across a room, the eye reads the conduit as a frame element, not an intrusion. It is a design choice, not a compromise.

For a Koramangala home office or a Sarjapur Road residential retrofit, the surface-mounted route also simplifies the shop drawing. The electrician does not need to coordinate with the glazier on cavity depth or conduit routing inside the frame. The conduit is specified on the elevation, the clips are ordered with the frame, and the installation sequence is linear. No site rework. No tint banding.

Retrofit dimming specifications: what the architect needs to specify upfront

The dimming cycle is not a given. It is a specification. When you commission a SmartGlass partition—whether Privato privacy glass in a bathroom or a full-height Studio conference partition—the specification document must include:

• Cycle time (e.g., clear-to-opaque in 0.8 seconds, opaque-to-clear in 1.0 seconds)
• Tint uniformity tolerance (e.g., no more than 5 percent variation in transmittance across the field when energised)
• Conduit routing method: surface-mounted or in-wall, with finish specification
• Relay and driver location (e.g., mounted on the partition frame, or in a remote control box)
• Environmental conditions during testing (humidity, temperature, power supply voltage tolerance)

If the specification is silent on conduit placement, the contractor will route it in-wall to save visible clutter. The glass will still function, but the dimming will lag, and the tint field will show banding. The retrofit is complete, the partition is installed, and the specification—as written—has been met. But the architect's intent has not.

Specify surface-mounted conduit upfront. Name the finish. Confirm the clip spacing. Require a shop drawing that shows the conduit route, the relay location, and the power and control connections. This is not over-specification; it is the difference between a dimming cycle that works and one that fails in the monsoon.

Bangalore micromarket retrofit case: HSR and Indiranagar precedent

In HSR Layout, a residential retrofit with a Notte blackout partition between bedroom and study was specified with in-wall conduit. The partition was framed in 50mm powder-coated aluminium, cavity depth 45mm. The electrician ran the conduit inside the cavity to keep the elevation clean. During the first monsoon cycle (July), the dimming response became unreliable. The glass would dim to 60 percent transmittance and stall. The relay was receiving power, but the voltage was dropping due to moisture on the contact pins inside the cavity.

The retrofit was re-specified with surface-mounted conduit, routed along the outer face and finished in matching powder-coat. The relay was relocated to a small enclosure mounted on the partition frame, outside the cavity. The dimming cycle returned to spec: clear-to-opaque in 0.9 seconds, uniform tint field, no banding. The visible conduit became a frame detail, not a defect.

The lesson for Indiranagar, Bellandur, and other Bangalore micromarkets with high-humidity monsoon exposure: specify the conduit route as a material specification, not an afterthought. The partition itself is the same. The glass is the same. The conduit placement determines whether the dimming works as intended.

Joint tolerance and site coordination: what the electrician and glazier need to align

When surface-mounted conduit is specified, the glazier and electrician must coordinate on two points: clip mounting and power feed location.

The clips are mounted to the partition frame at 400mm centres. The frame tolerance is ±2mm on the vertical. The clip is a 25mm stainless bracket with a 6mm fastener. The conduit sits in the clip with a 1mm clearance on either side. This tolerance stack is tight but achievable if both trades confirm the frame dimensions before the partition is assembled on site.

The power feed—the point where the conduit emerges from the wall and connects to the relay—must be located where the electrician can access it without cutting the conduit. If the relay is mounted on the partition frame itself, the power feed should exit the conduit within 300mm of the relay. If the relay is in a remote enclosure (mounted on the adjacent wall), the feed can exit at the top or bottom of the partition, depending on the site layout.

Require a shop drawing that shows both the clip locations and the power feed location, dimensioned from the partition datum. This drawing goes to both the glazier and the electrician. No surprises on site. No in-wall rerouting at handover.

Questions we get asked

Will visible surface-mounted conduit affect the partition's aesthetic in a residential setting?

The conduit is 16mm diameter, powder-coated to match the frame. In a 50mm frame, it reads as a frame element. From across a room, it is not visually distinct. If the frame is natural anodised aluminium, the conduit is anodised to match. If the frame is powder-coated black, the conduit is black. The aesthetic depends on finish consistency, not on whether the conduit is visible. We have specified surface-mounted conduit in Sadashivanagar and Jayanagar residential projects without client objection; the conduit disappears into the frame detail.

Can in-wall conduit work if the partition is ventilated?

Ventilation helps, but it does not eliminate the lag. Even with a small vent hole at the top and bottom of the cavity, air exchange during monsoon is slow. The humidity ingress exceeds the egress. The relay still sees intermittent voltage. If the project is in an air-conditioned space and the partition cavity is sealed with desiccant packs, in-wall conduit may be acceptable—but this adds cost and maintenance. Surface-mounted conduit is simpler and more reliable.

What is the cost difference between surface-mounted and in-wall conduit routing?

Surface-mounted conduit adds the cost of the conduit itself (approximately 250 to 350 rupees per metre), the stainless clips (50 rupees per clip, 10 to 12 clips per partition), and labour to secure the clips. For a 3-metre-high partition, the material cost is roughly 1200 to 1800 rupees. In-wall routing saves this cost but introduces the risk of dimming lag and tint banding during monsoon. The retrofit cost to fix the dimming issue (relocating the relay, rerouting the conduit) is 8000 to 12000 rupees. Specify surface-mounted conduit upfront.

Does the conduit need to be grounded?

The conduit itself does not carry high voltage—only control signals and low-power relay circuits. The conduit does not need to be grounded. The power supply (typically a 24V DC transformer) should be grounded to earth as per electrical code. The conduit can be plastic or metal; metal conduit does not improve electrical safety for a low-voltage SmartGlass circuit.

If we retrofit an existing partition with SmartGlass film, can we use in-wall conduit?

Retrofit film—such as Borsa Film applied to existing glass—carries the same electrical requirements as factory-laminated SmartGlass. The conduit must deliver clean power to the relay and driver. In-wall routing in an existing partition cavity is even riskier than new-build, because the cavity may already contain dust, debris, and moisture from years of use. Specify surface-mounted conduit for any retrofit film installation. The conduit is routed along the frame edge, outside the cavity, and the relay is mounted externally. This is the only reliable method for retrofit dimming in Bangalore's climate.

Commission a SmartGlass partition fitted to your site dimensions and your dimming specification. Bring the architect's intent and the atelier's craft together on the shop drawing. Talk to the atelier about conduit routing, relay placement, and the dimming cycle you need.