24/02/2026

Many Residential Welfare Associations (RWAs) across Tamil Nadu continue paying commercial electricity tariffs (LT-V) for essential infrastructure like Sewage Treatment Plants (STP), Water Treatment Plants (WTP), and fire-fighting systems, even when these serve only residents. This misclassification inflates common area expenses significantly.

Sri Sun Solar Energiser Pvt. Ltd. regularly audits RWA energy accounts and finds that proper tariff segregation as per TNERC Tariff Order 2023 can shift eligible loads to lower domestic common tariffs (LT I-D / I-E), subject to stipulated conditions on common area usage.

TNERC’s Position on STP, WTP and Fire Systems

The landmark Eden Park RWA (Siruseri) petition (M.P. No. 21 of 2021) initially clarified that under the 2017 tariff regime, domestic common supply was strictly limited to “common lighting, water supply and lifts” (T.P. No. 1 of 2017, para 5.2.3.11). STP, WTP and fire hydrant pumps were directed to remain under LT-V Commercial tariff.

However, the TNERC Tariff Order 2023 (T.O. No. 6 of 2023, dated 30.06.2023) expanded this scope significantly. Clause 6.2.2.1(h) now explicitly includes:

“This tariff [LT I-D] is applicable to common lighting, water supply, lift, Sewerage treatment plant, Water treatment plant, Fire Hydrant facility, Gym, Swimming pool, CCTV camera, Community hall, amphitheatre etc., for the purpose of residents only, with separate service connections.”

This provision recognises modern residential complexes’ infrastructure needs while maintaining safeguards.

Key Conditions for Domestic Common Tariff Eligibility

RWAs must meet all these TNERC-mandated conditions to avail LT I-D / I-E for STP/WTP/fire systems:

  1. Separate service connections for each facility (STP, WTP, fire pumps cannot share meters with ineligible loads).

  2. Residents-only usage – no commercial/external supply permitted.

  3. Common area allowance limit: In mixed-use complexes, non-residential built-up area must not exceed 25% of total built-up area. If >25%, all common facilities revert to LT-V Commercial tariff.

  4. Purely residential complexes automatically qualify without the 25% restriction.

Facility Eligible Tariff (if conditions met) Fallback Tariff TNERC Reference
STP/WTP LT I-D / I-E (Domestic Common) LT-V (Commercial) Clause 6.2.2.1(h) 
Fire Hydrant LT I-D / I-E (Domestic Common) LT-V (Commercial) Clause 6.2.2.1(h) 
Lifts/Pumps LT I-D / I-E (Domestic Common) LT-V (Commercial) Clause 6.2.2.1(h) 
 
 

Why RWAs End Up on Commercial Tariff

Common scenarios leading to higher LT-V billing:

  • Single meter syndrome: All common loads (lighting + STP + fire) on one commercial meter.

  • Mixed-use exceedance: >25% commercial area disqualifies entire common services.

  • Historical classification: Connections taken during construction, never segregated post-completion.

  • Lack of separate metering for STP/WTP/fire systems as required by TNERC.

Step-by-Step Action Plan for RWAs

  1. Audit Current Tariffs
    Check all EB bills for tariff codes (LT I-D/I-E vs LT-V). Note connected loads per meter.

  2. Verify Complex Eligibility
    Calculate non-residential built-up area % (shops/offices/total built-up area). Must be ≤25%.

  3. Segregate Loads

    • Meter 1 (LT I-D/I-E): Lighting, lifts, resident water pumps, STP/WTP/fire (if eligible).

    • Meter 2 (LT-V): Any ineligible/excess commercial loads.

  4. Apply for Reclassification
    Submit to TANGEDCO/TNPDCL:

    • Building completion certificate

    • RWA registration

    • Layout plan showing common areas

    • Load segregation diagram

    • Proof of ≤25% non-residential area (for mixed complexes)

  5. Install Separate Connections
    TNERC mandates separate service connections for STP/WTP/fire facilities.

Financial Impact Example

Scenario: RWA with 100 kW STP load consuming 50,000 units/month.

Tariff Rate (₹/unit) Monthly Bill Annual Savings
LT-V Commercial 9.50  ₹4,75,000 –
LT I-D Domestic 6.50  ₹3,25,000 ₹1,80,00,000
 
 

40%+ immediate reduction possible for eligible loads.

Sri Sun Solar Energiser’s RWA Support Services

We help RWAs implement TNERC 2023 provisions through:

  • Tariff compliance audits referencing Eden Park order and 2023 expansion

  • Load segregation feasibility studies with metering plans

  • Documentation for TANGEDCO tariff conversion to LT I-D/I-E

  • Solar integration for STP pumps/fire systems under net-metering (domestic tariff eligible)

  • 25% non-residential area calculations with architect certification

Real result: Recent client RWA saved ₹28 lakhs annually by segregating 150 kW STP/fire loads to LT I-D per TNERC Clause 6.2.2.1(h).

Important Caveats

  • Eden Park precedent still applies to pre-2023 connections unless formally reclassified.

  • Mixed complexes >25% commercial = No domestic tariff for any common services.

  • TNPDCL/TANGEDCO discretion on individual cases; appeals go to TNERC.

  • Solar rooftop/net-metering further optimises eligible domestic common loads.

Is your RWA’s STP/fire system on LT-V Commercial tariff? Verify eligibility under TNERC 2023 Clause 6.2.2.1(h) today.

Contact Sri Sun Solar Energiser Pvt. Ltd. for TNERC-compliant tariff optimisation and solar solutions.

📞 +91-9962001332 | 🌐www.srisunsolar.com | 📧 gokulraj@srisunsolar.com