Smart Prepaid Meter for Apartment Sub-Metering — How to Actually Set It Up in Chennai

Why a society goes prepaid in the first place

• No more manual reading. Someone walking every flat on the 1st of the month, arguing over readings — gone.
• Zero dues follow-up. Low balance auto-alerts go to the tenant's phone; supply auto-disconnects if they ignore it.
• Dispute resolution. Every reading, top-up and usage event is time-stamped in the dashboard.
• Common-area clarity. Lift, pump and common lights get their own meter so the society isn't absorbing someone else's usage.

Which Techno SKU for the job

For most apartment sub-metering we spec the Techno TMCB 012 SMART — single phase static prepaid meter with mobile app, remote disconnect, multi-tier communication.

For the main incomer we often add TMCB 013M (3 phase static) so the committee can reconcile society total vs sum-of-flats.

Comm options — RS485 vs RF vs GPRS

For a 40-flat building with one or two meter panels, RS485 is almost always cheapest and most reliable. For a scattered campus (rowhouses, villas, gated community with 20+ units across), RF wins.

Indicative cost per flat (ballpark)

We'll hold rupee figures — prices move — but the breakdown per flat typically looks like:

• 1 × TMCB 012 SMART meter
• 1 × Meter enclosure box (shared / per-flat)
• 1 × CT (if load > 30A) + 1 × gateway share
• Labour + wiring + testing
• Dashboard onboarding (one-time)

Share flat count + panel layout on WhatsApp and we quote an itemised per-flat BOQ.

Legal and process checklist

1. Society resolution — committee passes a resolution to switch common-area metering to prepaid. Paper trail protects committee members.
2. Tenant notice — 30-day written notice describing how tenants will top up, what happens on zero balance, support number.
3. TANGEDCO bill stays untouched — prepaid sub-meters sit downstream of the society's EB meter. EB continues to bill the society at the commercial tariff; sub-meters recover from flats.
4. Tariff setting — committee decides per-unit rate. Most societies set sub-meter tariff slightly above EB tariff to cover losses + maintenance + admin.
5. Top-up workflow — test the tenant app once meters are live. Recharge via UPI in the app > confirm balance update > test disconnect / reconnect flow.
6. Audit window — first 60 days, committee cross-checks sub-meter sum vs main EB meter. Losses > 3% means wiring / CT error — investigate.

Installation day — how it actually runs

1. Electrician isolates the main panel (pre-notified shutdown, usually 2–3 hours).
2. Each flat's feeder gets a TMCB 012 SMART in the common meter panel.
3. CTs (if needed) wired with matching polarity — P1/P2, S1/S2.
4. RS485 daisy-chain back to the gateway; gateway connects to society router or cellular SIM.
5. Dashboard onboarding — we bind each meter serial to flat number in the admin portal.
6. Each tenant gets a welcome message: download the app, set PIN, top up first balance.
7. Go-live test — force a remote disconnect on one meter to verify, then reconnect.

Common gotchas

• Tenant without smartphone — committee admin can top up on their behalf from the dashboard. No tenant is locked out.
• Meter tamper — TMCB 012 SMART logs every open / tamper event. Dashboard shows alert; committee follows up physically.
• Balance dispute — every top-up + every usage is time-stamped. Export CSV and share with tenant.
• Gateway internet down — meters continue working locally; readings sync when gateway reconnects.

When prepaid sub-metering might NOT be the right call

• Society with only 3–4 flats — simpler to just read meters manually.
• Owner-occupied community with no rental churn — less billing friction to begin with.
• Building in active redevelopment — wait till construction settles.

Related reads

• Smart prepaid meters — category
• Techno Meters brand page
• Techno vs L&T energy meters
• Panel meter 72x72 vs 96x96