1.3 Drawing Approval, NOCs, Inspection & Connection Workflows

1.3 Drawing Approval, NOCs, Inspection & Connection Workflows

The Statutory DEWA Project Lifecycle

Securing permanent electrical power supply from DEWA for new building developments, villa projects, commercial towers, or tenant fit-outs in Dubai follows a mandatory, multi-stage statutory workflow. Electrical consultants and Grade-certified contractors navigate DEWA's integrated e-Services Submission Portal to submit technical drawings, obtain No Objection Certificates (NOCs), schedule physical site inspections, and secure final energization.

Understanding each procedural phase is essential for electrical engineers to avoid costly project delays, portal rejections, or installation non-compliance.

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Stage 1: No Objection Certificates (NOCs) & Utility Clearances

Before initiating physical site excavation or structural foundation works, contractors must obtain relevant No Objection Certificates via the Dubai Unified Building Permit System or DEWA e-Services:

• Infrastructure & Utility NOC: Confirms that proposed building foundations, boundary walls, or external drainage trenches do not encroach upon existing DEWA high-voltage underground cables, 132kV transmission corridors, or water pipelines.
• Building Electrical NOC: Establishes initial technical clearance for electrical grid capacity availability at the specific plot location.
• Demolition NOC: Required prior to demolishing existing structures to ensure existing DEWA service cables are safely isolated, revenue meters recovered, and supply points disconnected.

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Stage 2: Load Estimation & Substation Space Allocation

During conceptual design, the electrical consultant calculates the total Connected Load (CL) and Maximum Demand (MD) in kVA by applying standardized DEWA diversity factors across lighting, power, HVAC, and power equipment.

Substation Space Allocation Thresholds

• Connected Load up to 400 kVA: Supplied directly from DEWA low-voltage feeder pillars or boundary-mounted service turrets. No internal substation space allocation is required.
• Connected Load Exceeding 400 kVA: Mandates the dedicated allocation of ground-floor or basement space within the building footprint for an indoor DEWA 11kV/400V Distribution Substation.
• Connected Load Exceeding 5 MVA to 10 MVA: Requires space allocation for multiple 11kV substations or a 33kV/11kV intermediate primary substation.

Substation Room Architecture Criteria

Substation spaces provided to DEWA must satisfy rigid architectural and access parameters:

• Direct, unobstructed ground-level vehicular access for DEWA heavy equipment and transformer delivery trucks.
• Minimum clear room height of 4.2 meters.
• 2-hour fire-rated walls, doors, and cable trench seals compliant with Dubai Civil Defense rules.
• Concrete oil containment bund walls capable of holding 100% of transformer oil volume.

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Stage 3: Detailed Electrical Drawing Submission & SLD Approval

Once load allocations and architectural plans are finalized, the Grade-certified contractor or consultant uploads full engineering packages to the DEWA e-Submission portal.

Mandatory Submission Drawings

1. Electrical Single Line Diagrams (SLDs): Comprehensive schematics illustrating power distribution from incoming DEWA MV supply / LV main switchboard down to sub-main boards (SMDBs) and final distribution boards (DBs). SLDs must clearly display breaker frame/trip ratings (ACB, MCCB, MCB), busbar ratings, short-circuit capacities, cable sizes/types, CT ratios, and protective relay settings.
2. Schedule of Loads: Detailed tabulations for all distribution boards detailing circuit numbers, phase assignments (L1, L2, L3 balancing), connected kW/kVA, diversity factors, and calculated maximum demand.
3. General Arrangement & Cable Routing Plans: Architectural floor plans indicating MDB room layouts, meter cabinet positions, riser locations, cable tray routes, and earthing pit layouts.
4. Earthing & Lightning Protection Layouts: Earth grid layout drawings, soil resistivity test reports, and earth resistance calculations.

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Stage 4: Pre-Inspection Testing & Pre-Commissioning

Following approval of electrical drawings and physical installation on site by licensed wiremen, the contractor MUST perform thorough internal pre-commissioning testing before requesting a DEWA inspection.

Mandatory Pre-Inspection Verification Tests

• Insulation Resistance Test: Conducted at 500 V DC for low-voltage circuits. Minimum acceptable insulation resistance is 1.0 Megaohm (healthy installations typically exceed 50–100 MΩ).
• Earth Electrode Resistance Test: Measured using the 3-pole fall-of-potential method. Per the DEWA Regulations for Electrical Installations, the main earth electrode resistance shall not exceed 1.0 Ohm for each incoming DEWA supply/MDB, and the resistance from any point of the earth continuity conductor to the main earth electrode shall not exceed 0.5 Ohm (DEWA substation earthing grids are also designed to stay below 1.0 Ohm).
• Earth Continuity & Bonding Test: Confirms continuous low-resistance protective conductors between MET and all exposed metallic enclosures ($R < 0.5\text{ }Ω$).
• Polarity Test: Verifies that all single-pole protective devices (MCBs) and switches are connected exclusively in phase conductors.
• Residual Current Device (RCD) Test: Verifies trip times for 30mA RCDs (must trip within 300 ms at $1\times I_{\Delta n}$ and within 40 ms at $5\times I_{\Delta n}$).

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Stage 5 & 6: Booking & Conducting DEWA Site Inspection

Upon completing pre-commissioning tests, the contractor books a physical site inspection via DEWA e-Services, uploading signed test sheets and as-built drawings. DEWA inspectors attend site within 3 to 5 business days to audit:

1. Switchroom Access & Safety: Clearances around MDB panels, rubber matting, trench covers, ventilation, and emergency lighting.
2. MDB & SMDB Audit: Panel label compliance, breaker ratings matching approved SLDs, phase isolation barriers, and torque seal marks.
3. Metering & Earthing: CT chamber sealing facilities, potential test block (PTB) layout, main earthing bar connections, and earthing pit access.

If non-compliances are detected, a rejection report is generated listing corrective items. Rectifications must be completed prior to re-booking inspection.

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Stage 7: Connection, Metering & Energization

Upon passing field inspection, DEWA issues an official Inspection Clearance Certificate. The client settles required security deposits and connection fees, following which DEWA meter technicians install and seal smart revenue meters. DEWA operations personnel perform final energization, verifying 400V/230V voltage levels and clockwise (L1-L2-L3) phase rotation.