Direct Answer
To select the right low voltage switchboard for a Saudi industrial facility, determine the maximum demand current from the load schedule with a minimum 20% growth margin, obtain the prospective fault current from the transformer and utility supply, define the site environmental class and IP requirement, establish the segregation level needed for the application, and verify compliance with IEC 61439-1. These five parameters current rating, fault withstand, IP rating, segregation form, and standard compliance completely define the switchboard specification.
Key Selection Factors
1. Load Capacity (Rated Current)
The switchboard's busbar and incomer ACB must carry the maximum demand current continuously without exceeding thermal limits. Rated currents for EAMFCO LV switchboards range from 400A to 6,300A.
Calculate: I = (kVA × 1,000) ÷ (√3 × 400). Apply diversity factor and add 20–25% growth margin. Round up to the next standard ACB rating.
2. Short Circuit Withstand Rating
The switchboard must withstand the prospective fault current at its incomer without catastrophic failure. This is determined by the transformer kVA, impedance percentage (%Z), and the upstream MV fault level.
A 2,000 kVA transformer at 5% impedance delivers approximately 28 kA prospective fault current at the LV terminals. Specify busbars and incomer ACB rated ≥ this value typically 50 kA or 65 kA for Saudi industrial applications.
3. Environmental Conditions
IEC 61439-1 rates assemblies at a maximum 40°C ambient. Saudi Arabia's industrial environments routinely exceed this outdoor sites reach 50–55°C in summer, and indoor rooms without dedicated cooling can sustain 45–50°C.
Specify the actual maximum site ambient in the data sheet. At temperatures above 40°C, the switchboard manufacturer must derate busbar current capacity or add forced cooling. Failure to specify ambient correctly leads to nuisance tripping and premature component failure.
4. Expansion Requirements
Specify a minimum 20% spare outgoing feeder ways beyond the initial population. Confirm the horizontal busbar has full-length capacity for the spare ways. For large industrial MDBs, 30–40% spare is justified.
Additionally, confirm whether a bus-coupler arrangement (two incomer ACBs with a tie ACB between bus sections) is required for future parallel transformer operation or supply changeover without interruption.
5. IP Rating for Saudi Environments
Match the IP rating to the installation environment:
- • Indoor, air-conditioned room: IP41 or IP43
- • Indoor, industrial/dusty: IP54
- • Outdoor, sheltered canopy: IP55
- • Outdoor exposed / sand: IP65
- • Coastal (salt spray zone): IP65 + marine coating
EAMFCO switchboards are available in IP43, IP55, and IP65.
6. Compliance Standards
All switchboards for Saudi projects must comply with:
- • IEC 61439-1 - general assembly requirements
- • IEC 61439-2 - power switchgear assemblies (PSC)
- • IEC 60947-2 - circuit breakers within the assembly
- • SASO - mandatory Saudi product certification
- • SEC Standards - for SEC-metered installations
Saudi Aramco and NWC projects have additional documentation requirements: type test reports, material certificates, and factory test (FAT) records.
Specific Considerations for Saudi Arabia's Harsh Climate
Saudi Arabia's operating environment is one of the most demanding in the world for electrical equipment. Three climate factors require explicit attention in every switchboard specification:
Extreme Heat Busbar Derating
IEC 61439-1 defines temperature rise limits based on a 40°C reference ambient. For every 10°C above this reference, the allowable temperature rise of current-carrying parts decreases meaning the busbar must carry less current to stay within thermal limits. A 3,200A busbar rated at 40°C ambient must be derated to approximately 2,880A at 50°C ambient if the thermal margin is not built in at the design stage.
Correct approach: State the maximum site ambient temperature in the switchboard data sheet and require the manufacturer to verify busbar ratings at that temperature. EAMFCO performs thermal verification calculations per IEC 61439-1 Annex D for all Saudi project switchboards.
Sand and Dust Ingress IP Rating and Filter Maintenance
Windborne sand in Saudi Arabia's Eastern Province, Central Region, and remote sites creates a dual problem for switchboards: sand clogs ventilation louvres, causing overtemperature, and fine dust settles on busbar insulation, creating creepage paths that can lead to tracking and flashover over time.
For any switchboard not in a positively pressurised, filtered electrical room: specify IP54 minimum for dusty indoor environments, IP65 for any outdoor installation. For forced-ventilated switchboards, specify sand-filtered air inlets with thermostatically controlled fans, and include filter replacement in the maintenance schedule.
Coastal Corrosion Material and Coating Specification
Sites within 5 km of the Arabian Gulf or Red Sea coastline Jubail Industrial City, Yanbu, Jeddah, Ras Al Khair are in a salt-laden corrosion zone. Standard mild steel enclosures with powder coat finish corrode within 3–5 years in these conditions.
For coastal installations: specify hot-dip galvanised structural steel with polyester powder coat over primer, stainless steel fasteners, and marine-grade gland plate materials. Busbar connections at cable terminations should be tin-plated and sealed with anti-oxidant compound. EAMFCO provides marine-specification switchboard finishes as a standard option for coastal Saudi sites.
An EAMFCO switchboard specified with correct IP rating, verified busbar derating for site ambient, and marine-grade coating adds a modest cost premium at manufacture but avoids the far higher cost of premature failure, emergency replacement, and unplanned production downtime in a harsh Saudi operating environment.
Step-by-Step Switchboard Selection Process
Compile the Electrical Load Schedule
List every load connected to the switchboard: equipment name, rated power (kW or kVA), power factor, starting method, and operating mode (continuous, intermittent, or standby). This is the non-negotiable starting point a switchboard cannot be correctly specified without it.
Apply diversity and demand factors per the project's design basis. For mixed industrial loads, typical demand factor is 0.70–0.85. For data centres, demand factor approaches 1.0 (all loads are continuous and must run simultaneously).
Calculate Maximum Demand Current
Sum the apparent power (kVA) from the load schedule after applying diversity. Convert to three-phase current at 400V:
Add a minimum 20% growth contingency and select the next standard incomer ACB rating: 630A, 800A, 1,000A, 1,250A, 1,600A, 2,000A, 2,500A, 3,200A, 4,000A, 5,000A, 6,300A.
Determine the Prospective Fault Current
Calculate the maximum prospective short circuit current (Isc) at the switchboard incomer. For an LV switchboard fed from a single transformer:
Example: 2,000 kVA transformer at 5% impedance → Isc ≈ 2,887A ÷ 0.05 = 57,735A (≈ 58 kA). Specify switchboard fault withstand ≥ 65 kA for 1 second to cover this with margin.
For switchboards fed from multiple parallel transformers, the fault level increases proportionally confirm with the project HV/LV system study.
Define Environmental Class and IP Rating
Visit the proposed switchboard location and document the worst-case environmental conditions: maximum ambient temperature, dust and sand exposure level, proximity to coast, presence of corrosive chemicals, and whether the location is indoor or outdoor. Map these to an IP rating requirement. State the maximum ambient in the data sheet not the IEC reference 40°C.
Specify Segregation Form
| Application | Recommended Segregation Form |
|---|---|
| General industrial MDB standard duty | Form 2b or Form 3 |
| Process plant continuous operation, reduced maintenance windows | Form 3b or Form 4A |
| Data centre, hospital, critical infrastructure | Form 4B full individual unit enclosure |
| Commercial building SMDB standard duty | Form 2b |
| Outdoor or harsh environment switchboard | Form 2b minimum + IP65 enclosure |
Define the Outgoing Feeder Schedule
List each outgoing circuit: circuit reference, load description, rated current (A), MCCB or ACB rating, cable entry direction (top or bottom), and whether draw-out or fixed mounting is required. Add 20–30% spare ways to the initial feeder count. Confirm the busbar extends to serve all spare ways.
Specify Metering and Instrumentation
For SEC-connected switchboards: include a revenue-class current transformer (CT) with accuracy class 0.5S and a multifunction energy meter recording kWh, kVARh, power factor, and maximum demand. For process facilities with SCADA: specify Modbus RTU or Modbus TCP output from the power meter. For Saudi Aramco projects: confirm IACS (Integrated Automation and Control System) interface requirements before ordering.
Issue Data Sheet and Request FAT
Document all selections in a formal switchboard data sheet and issue with the RFQ. Require a Factory Acceptance Test (FAT) as a contractual deliverable: dielectric testing, continuity, insulation resistance, functional testing of all breakers and meters, and IP test verification. The FAT report forms part of the O&M handover documentation.
Why Custom-Built Switchboards Are the Right Solution for Saudi Industrial Projects
Off-the-shelf switchboard assemblies built to a standard catalogue configuration cannot address the specific combination of high ambient temperature, sand ingress, coastal corrosion, project-specific feeder schedules, and Saudi regulatory requirements that characterise Saudi industrial projects.
Custom-built LV switchboards from EAMFCO are engineered to the project's actual load schedule, fault level, site ambient, and outgoing feeder configuration with full IEC 61439-1 compliance verified at the design stage and confirmed by factory testing. This approach eliminates the compromises inherent in catalogue selection and produces a switchboard that will perform correctly for the full design life at the actual operating site.
EAMFCO's manufacturing capability covers the full range of Saudi switchboard applications:
| Application | Typical Rating | Features |
|---|---|---|
| Main Distribution Board (MDB) | 1,600A–6,300A | ACB incomer, full metering, Form 4B, IP43–IP65, bus coupler option |
| Sub-Main Distribution Board (SMDB) | 400A–2,500A | MCCB or ACB incomer, partial metering, Form 2b–4A |
| Dual-bus MDB with bus-coupler | 2,500A–6,300A | Two incomer ACBs + tie ACB, interlocked for N+1 operation |
| Outdoor weatherproof MDB | 800A–4,000A | IP65 enclosure, forced ventilation with sand filter, marine coating |
| Data centre main LV switchboard | 2,500A–6,300A | Form 4B, draw-out ACBs, dual bus, SCADA integration, UPS bypass |
Common Mistakes to Avoid When Specifying Switchboards in Saudi Arabia
Mistake 1: Specifying for 40°C Ambient in a 50°C Environment
The Error
Ordering a standard IEC 61439-1 switchboard without stating the actual site ambient temperature. The manufacturer builds to the 40°C reference at 50°C, busbars run above thermal limits, insulation ages rapidly, and ACB thermal trips become unreliable.
The Correct Approach
Always state the maximum site ambient temperature in the switchboard data sheet. Require the manufacturer to confirm busbar ratings at that ambient, or apply forced ventilation to bring the internal temperature within the equipment's rated range.
Mistake 2: Undersizing for Short Circuit Withstand
The Error
Specifying a switchboard busbar rated at 36 kA when the transformer and utility fault level combination delivers 55 kA prospective fault current. On first major fault, the busbar fails catastrophically with risk to personnel and complete loss of the switchboard.
The Correct Approach
Calculate the prospective fault current for the specific transformer and upstream MV fault level. Specify busbars and incomer breakers rated at least 10% above the calculated value. For Saudi industrial applications, 50 kA or 65 kA for 1 second is standard.
Mistake 3: No Spare Feeder Ways
The Error
Specifying the switchboard with exactly the number of outgoing feeders required today. Within 2–3 years, additional loads require a switchboard extension section requiring a planned outage for busbar extension work and a capital cost that dwarfs the original saving from omitting spare ways.
The Correct Approach
Specify 20% spare outgoing ways as standard. For industrial plants with significant planned future expansion, specify 30–40% spare. Confirm the horizontal busbar extends to all spare ways at the time of manufacture, not just to the populated section.
Mistake 4: Wrong IP Rating for the Site
The Error
Installing an IP43 switchboard in an outdoor yard or in a non-air-conditioned plant room that experiences windborne sand. Within months, dust accumulates on busbar insulation, trips increase, and a high-current fault from tracking damage causes a complete MDB failure requiring full replacement.
The Correct Approach
Assess the actual installation environment before specifying not just the intended one. Specify IP54 for any dusty indoor environment and IP65 for any outdoor installation in Saudi Arabia. Specify sand-filtered forced ventilation for outdoor enclosures where heat dissipation is required.
Mistake 5: Omitting Factory Acceptance Testing
The Error
Accepting a switchboard without a Factory Acceptance Test (FAT) to save time or cost. Faults in internal wiring, incorrect CT ratios, misconfigured trip units, or damaged IP seals are discovered on site where correction is far more expensive than at the factory and may delay project energisation.
The Correct Approach
Require a FAT for all switchboards regardless of size. The FAT should cover: insulation resistance testing of all circuits, functional testing of all ACBs and MCCBs, metering calibration verification, IP seal inspection, and review of trip unit settings against the coordination study. The FAT report is a required handover document.
Frequently Asked Questions
Q: How do I calculate the switchboard rating I need for my facility?
A: Start with the connected load schedule. Calculate apparent power (kVA = kW ÷ power factor) for each load. Sum and apply a diversity factor (0.65–0.85 for mixed industrial loads). Convert to rated current: I = kVA × 1,000 ÷ (√3 × 400). Add 20–25% growth margin and select the next standard ACB rating. EAMFCO provides load schedule review and switchboard sizing calculations as part of the specification process.
Q: What short circuit withstand rating should I specify for a switchboard in Saudi Arabia?
A: The rating must meet or exceed the prospective fault current at the switchboard incomer. For a 2,000 kVA transformer at 4% impedance on a 13.8 kV supply, the prospective LV fault current is approximately 28–33 kA. EAMFCO switchboards are available at 50 kA and 65 kA for 1 second, covering the full range of Saudi industrial transformer sizes.
Q: Does a switchboard need to be custom-built for Saudi Arabia's climate?
A: Standard IEC 61439-1 switchboards are rated for 40°C maximum ambient. Saudi outdoor and many industrial indoor environments exceed this. Custom-built switchboards incorporate site-specific busbar derating, forced ventilation for ambient management, IP65 enclosure for sand and dust, and marine-grade coatings for coastal sites none of which are possible with off-the-shelf catalogue products.
Q: How many spare feeder ways should I include in a switchboard?
A: Specify a minimum of 20% of initially populated ways as spare with full busbar extension and cable termination space. For large MDBs in industrial plants with anticipated expansion, 30–40% spare is justified. Spare ways cost very little at manufacture; adding them after commissioning requires a switchboard extension section and a planned outage.
EAMFCO Custom LV Switchboards, Engineered for Saudi Industrial Conditions
EAMFCO manufactures low voltage switchboards rated up to 4000A, with IEC 61439-1 compliance, Form 4B segregation, IP65 protection, and busbar ratings verified for Saudi ambient temperatures. Our engineering team provides load schedule review, fault current calculations, and switchboard data sheet preparation as part of the project specification process. Continue reading: