SmartGlass dimming relay hesitation in a Hennur partition: why 2-second lag isn't a defect—it's a humidity-path wiring issue architects must address in the electrical handover spec

You've specified a Studio partition in frameless PDLC glass for a Hennur home office. The glass arrives, fits to the millimetre, the power feed is live. You press the remote. The glass takes two seconds to shift from clear to tinted. Not one. Not three. Two. Every time. The client notices. You wonder if it's a manufacturing defect. It isn't. The delay lives in the electrical handover spec—specifically, how the low-voltage relay wiring was routed through the load-bearing partition during the concrete pour.

Why the relay hesitates: moisture in the signal path

PDLC glass (polymer-dispersed liquid crystal) operates on a simple principle: apply 48V DC across the cell, the crystals align, the glass tints. Kill the voltage, they scatter, it clears. The relay that switches this voltage sits in a wall-mounted junction box, typically 400mm from the partition edge. The signal wire—a twisted pair, usually 0.5mm² or 0.75mm²—runs from the remote receiver to the relay coil.

In a Bangalore home office, that signal wire often runs through in-wall PVC conduit embedded in the load-bearing partition during the concrete pour. During the monsoon months (June through September), when relative humidity climbs to 85–92%, moisture wicks into the conduit. The conduit itself isn't sealed at either end until the electrician terminates it. By the time the glass is commissioned, the air inside that 2-metre run of conduit carries 60–70% relative humidity. This moisture sits around the relay coil terminals.

When you press the remote, the receiver sends a signal down the twisted pair. That signal has to overcome the capacitive load created by moisture around the coil windings. The relay doesn't fail—it hesitates. The coil energises, but not instantly. The hesitation is typically 1.5 to 2.5 seconds, depending on how much moisture is present and the ambient temperature at that moment (colder air holds less moisture, so the lag may be shorter in winter).

The Bangalore climate context: why this happens here

Bangalore's post-monsoon humidity is not a defect in the building envelope—it's a fact of the climate. The Cauvery hard water (TDS around 200–300 ppm) that flows through the city's supply lines also means that any moisture that condenses on metal surfaces tends to stay put; it doesn't evaporate as quickly as it would in a drier region. In HSR Layout, Koramangala, or Indiranagar, where tech-corridor housing has driven up the density of home offices and smart-glass partitions, this issue appears in roughly 15–20% of commissioned SmartGlass installations.

The delay is not a manufacturing defect. The relay is operating within its rated coil resistance (typically 180–220 ohms for a 48V DC relay). The glass cell itself responds within 200 milliseconds. The lag is purely electrical—a function of how long it takes the relay coil to overcome the capacitive load in the signal path.

How the electrical handover spec should address this

Conduit sealing at both ends

The first intervention is the simplest: seal the conduit at both the relay end and the receiver end with silicone-filled grommet seals or closed-cell foam plugs. This prevents moisture ingress during and after the concrete pour. The cost is negligible—roughly 80–120 rupees per seal—but it must be specified in the electrical handover document, not left to site discretion.

Many electrical contractors treat conduit sealing as optional. It isn't. Specify it as a mandatory line item: "All low-voltage signal conduit runs shall be sealed with closed-cell foam end plugs until final termination. Plugs to remain in place until power-up testing."

Dehumidification of the signal path

If the conduit is already in place and the hesitation has already appeared, the relay can be temporarily de-energised, and the conduit can be blown through with dry compressed air (15–20 PSI, 2–3 minutes per run). This evaporates the moisture. The effect lasts 3–6 weeks, depending on how sealed the conduit ends are. It's a temporary fix, not a permanent one.

For a permanent fix after installation, the conduit should be re-sealed and the space left to air-dry over 2–3 weeks in the dry season (January–March). In monsoon, this isn't practical.

Relay selection and placement

Some contractors specify relays with sealed coil housings (potted relays) rather than open-frame types. A potted relay costs 30–40% more but eliminates the capacitive load issue entirely. If you're specifying a new installation, ask your electrical consultant whether the relay is potted or open-frame. Potted relays are the better choice for humid climates.

Placement also matters. The relay should sit in a wall-mounted junction box that is itself sealed—not in a loose conduit run. The box should have a removable cover plate, not a permanently sealed one, so that moisture can be inspected and managed during commissioning.

Commissioning protocol: what to check before handover

When you commission a SmartGlass partition, the electrical contractor should run a timing test. Press the remote 10 times in succession. Measure the delay from button press to visible tint shift using a stopwatch. Document the result. If the delay is consistently under 1 second, the signal path is clean. If it's 2 seconds or more, the conduit needs to be re-sealed and the relay housing inspected for moisture.

This test should be part of your handover checklist, not an afterthought. Include it in the specification: "SmartGlass dimming response time shall not exceed 1 second from remote actuation to visible tint shift. Timing to be verified at three points: immediately after power-up, after 30 minutes of continuous use, and after a 4-hour idle period. Results to be documented on the commissioning sheet."

If the client is in a Whitefield or Sarjapur Road project where the building is still under construction, insist that the electrical contractor seal the conduit before the concrete pour. If you're retrofitting Borsa smart film onto existing partitions, the signal wiring is external and this issue doesn't arise—but the relay placement still matters.

Specifying around the issue: a sample clause

Here's language you can adapt for your next electrical specification:

• All low-voltage PDLC control wiring (signal and power) shall run in separate PVC conduit, one conduit per circuit.
• Conduit shall be sealed at both ends with closed-cell foam grommet plugs until final termination.
• The PDLC relay shall be mounted in a sealed wall-mounted junction box with a removable cover plate. The box shall not be sealed permanently.
• At commissioning, the dimming response time shall be measured and documented. Response time is defined as the interval from remote button press to visible tint shift. Maximum acceptable response time: 1 second.
• If response time exceeds 1.5 seconds at commissioning, the conduit shall be purged with dry compressed air and re-sealed. The test shall be repeated after 48 hours.

Why this matters for your project timeline

A 2-second delay doesn't sound like much. In a home office, the client will notice it every time they press the remote. They'll assume the glass or the control system is faulty. You'll be back on site troubleshooting. By addressing the electrical handover spec upfront, you avoid the call-back and the client frustration.

This is especially important in Bangalore's tech-corridor projects—Whitefield, Indiranagar, Koramangala—where clients are accustomed to fast, responsive interfaces. A dimming system that hesitates feels broken, even if it's working perfectly.

Questions we get asked

Does this happen with all PDLC glass, or just ours?

It happens with all PDLC glass that uses a relay-switched 48V DC circuit. The issue is in the electrical infrastructure, not the glass cell. Any manufacturer's glass will exhibit the same delay if the signal wiring runs through an unsealed, moisture-laden conduit.

Can I fix this after the glass is already installed?

Yes, but it requires access to the conduit and the relay. If the conduit is embedded in the concrete, access is limited. If it's surface-mounted, you can unseal the ends, blow through with dry air, and re-seal. The effect lasts a few weeks. For a permanent fix, the conduit should be re-routed or the relay should be replaced with a potted unit.

Does the delay get worse over time?

Not significantly. Once the conduit has absorbed moisture to equilibrium (usually 2–4 weeks after the pour), the delay stabilises. It may vary slightly with seasonal humidity changes, but it won't worsen progressively. If the delay suddenly increases, it suggests a new moisture source—a leak, or condensation from an air-conditioning duct nearby.

Should I specify a potted relay for all my projects?

If you're working on a project in Bangalore during or just after the monsoon season (July–October), yes. The extra cost (roughly 1,200–1,600 rupees per relay versus 800–1,000 for an open-frame unit) is worth the certainty. If you're working in the dry season and the conduit is properly sealed, an open-frame relay is fine.

How do I explain this to the client?

Tell them the truth: the delay is a result of how the electrical wiring was routed through the building structure, not a defect in the glass. It's fixable. And it's preventable on future projects by specifying sealed conduit and potted relays. Most clients appreciate the technical clarity and the solution-oriented approach.

If you're commissioning a SmartGlass partition in your next Bangalore project and want to avoid this issue altogether, talk to the atelier about your electrical handover spec. We can review the relay placement and conduit routing with your electrical consultant before the concrete pour.