## TL;DR

Sizing a 750 kVA generator for a Saudi high-rise involves strict adherence to Saudi Electricity Company (SEC) and SASO standards. Unlike industrial applications, residential towers have high peak demands from elevators and fire pumps, which create significant voltage dips during startup. A 750 kVA unit is often the 'sweet spot' for medium-to-large towers, but its effective capacity must be calculated at 50°C to ensure reliability during Riyadh or Jeddah summers. Procurement managers must factor in the running kW of essential loads (lighting, basic HVAC, water pumps) and add a substantial surge allowance for fire safety systems mandated by Saudi Civil Defence. The generator must comply with ISO 8528 and NFPA 110. If the load exceeds 750 kVA, the next step on the rating ladder is 1000 kVA. Always ensure the unit is IECEE certified for import and local installation.

## Calculating the standby diesel generator duty point

The duty point for a 750 kVA residential generator is split into 'Essential' and 'Life Safety' loads. Start with the steady-state load: sum the kW for common area lighting, one elevator per bank, and domestic water pumps. Apply the formula: kVA = (Running kW / 0.8 PF) × 1.25. For a 750 kVA rating, your steady-state load should realistically hover around 480 kW (480 / 0.8 * 1.25 = 750). The 'Duty Point' must also include the largest motor starting event. In a high-rise, this is typically the fire pump. If the fire pump is 110 kW, its starting kVA can momentarily exceed 600 kVA. The 750 kVA generator must have an alternator designed with a high motor-starting capability (SkVA) to prevent the voltage from dropping below 85%, which would cause the lift controllers to fault and trap residents.

## Standards and Saudi codes that apply

In Saudi Arabia, the Saudi Electricity Company (SEC) provides the primary technical circulars for generator connection. Compliance with SASO (Saudi Standards, Metrology and Quality Organization) and IECEE certification is mandatory for all imported diesel gensets. For high-rise buildings, Saudi Civil Defence strictly enforces NFPA 110 for emergency power systems, which categorizes generators by 'Level' and 'Class'. A residential tower typically requires Level 1 (life safety impact) and Class 2 or higher (fuel autonomy). The generator must also meet ISO 8528-5 for transient performance, ensuring that when a large elevator load is applied, the frequency and voltage recover within specified limits. Additionally, IEC 60034 applies to the alternator construction to ensure it can withstand the high ambient temperatures and potential sand ingress common in the Kingdom.

## Common procurement traps for high-rise residential tower

A major trap in Saudi Arabia is 'Fuel System Mismanagement'. High-rises often have the generator in the basement or on a podium, requiring complex fuel transfer systems. If the day tank and transfer pumps are not sized to NFPA 110 standards, the 750 kVA engine will starve during an extended outage. Another trap is 'Step Loading'. SEC codes may require the generator to take 100% of the emergency load in a single step. Many cheaper 750 kVA units can only handle a 60% first-step load before the engine speed drops too far. Buyers should also watch for 'Sound and Vibration'. In a luxury residential tower, a standard 85 dB(A) enclosure is unacceptable; a super-silent canopy (70-75 dB(A)) and high-efficiency anti-vibration mounts are essential to prevent resident complaints.

## Worked example for a 750 kVA residential tower

Consider a 20-storey tower in Riyadh.

Step 1: Steady-state load calculation. Lighting (50 kW) + 2 Elevators (60 kW) + HVAC for lobby (100 kW) + Water pumps (40 kW) = 250 kW.

Step 2: Base kVA = 250 / 0.8 = 312.5 kVA.

Step 3: Add 25% growth/ambient margin: 312.5 × 1.25 = 390.6 kVA.

Step 4: Fire Pump Surge. The fire pump is 132 kW. Starting SkVA (Star-Delta) = 132 / 0.8 * 3.5 = 577.5 kVA.

Step 5: Total Transient Check. When the fire pump starts, the generator is already carrying 312.5 kVA. Total momentary demand = 312.5 + 577.5 = 890 kVA.

Recommendation: A 750 kVA generator with a high-performance alternator (rated for 1000+ SkVA at 30% voltage dip) is required. If the alternator is standard-duty, you would have to round up to a 1000 kVA unit to handle the fire pump surge without flickering the lights throughout the tower.

### What are the SEC requirements for standby generators in Saudi Arabia?

SEC requires a formal 'No Objection Certificate' (NOC) for generator installation. The system must include an isolation switch and an ATS that prevents parallel operation with the SEC grid unless specifically permitted for peak shaving.

### Why is IECEE certification important for generators in KSA?

IECEE certification ensures that the generator and its components meet international safety standards. Without this certificate, the equipment may be held at Saudi customs or fail to receive an operational permit from SASO.

### How much fuel storage is required for a residential generator in KSA?

Per Saudi Civil Defence and NFPA 110, a 'Class 8' or higher system is often required, meaning the generator must have enough fuel on-site to run for at least 8 to 24 hours at full load, depending on the building's occupancy type and height.

How to size a 750 kVA standby diesel generator for a Saudi high-rise residential tower