Definition
A low voltage switchboard is a free-standing electrical assembly that receives incoming power from a transformer or utility supply at voltages up to 1,000V AC, and distributes it to outgoing circuits through protective devices including circuit breakers, fuses, and contactors. It forms the primary power distribution point of an industrial or commercial electrical installation, housing metering, protection, and control equipment within a single rated enclosure.
The Role of a Switchboard in Industrial Power Distribution
In an industrial or large commercial facility, electrical power arrives from the utility network or an on-site generator at medium voltage (MV) typically 13.8 kV or 33 kV in Saudi Arabia. A transformer steps this down to low voltage (400V three-phase at 50 Hz). The transformer secondary connects via busduct or cable to the main LV switchboard, which performs four functions simultaneously:
Incoming Protection
The main circuit breaker or switch-disconnector isolates the entire LV installation from the transformer on fault or for maintenance the single point of isolation for the complete facility.
Load Distribution
Outgoing feeder breakers distribute power to sub-distribution boards, motor control centres, and large individual loads controlling current path and capacity for each circuit.
Fault Discrimination
Selective trip coordination between the main breaker and outgoing feeders ensures a downstream fault trips only the affected feeder, not the entire facility supply.
Measurement & Monitoring
Metering instruments record kWh, kVAR, power factor, voltage, and maximum demand inputs to SEC billing, facility energy management, and SCADA systems.
EAMFCO's low voltage switchboards handle the full scope of main electrical distribution from the Main Distribution Board (MDB) at the transformer secondary through to Sub-Main Distribution Boards (SMDB) serving individual building zones or process areas.
Key Components of a Low Voltage Switchboard
Main Incoming Breaker (ACB)
up to 6,300AMain Busbar Assembly
99.99% tinned copperOutgoing Feeder MCCBs / ACBs
Form 3 / Form 4BMetering & Instrumentation
Revenue / check meterNeutral & Earth Busbars
TN-S / TN-C-SEnclosure & Segregation
IP43 / IP55 / IP65How a Switchboard Differs from a Panelboard
The terms are often used interchangeably in the field, but they describe different equipment with different ratings, construction, and applications. Understanding the distinction matters when specifying distribution equipment for Saudi projects:
| Parameter | LV Switchboard | Panelboard / Distribution Board |
|---|---|---|
| Rated current | 400A to 6,300A | Typically ≤ 400A (IEC) or ≤ 1,200A (NEC) |
| Physical size | Free-standing, floor-mounted multi-section | Wall-mounted or recessed compact single enclosure |
| Construction | Modular, draw-out or fixed functional units, large busbar | Fixed components, smaller busbar, limited modularity |
| Incoming device | Air Circuit Breaker (ACB) adjustable trip unit | MCCB or main switch fixed or adjustable |
| Segregation level | Form 2 to Form 4B per IEC 61439 | Typically Form 1 no internal segregation |
| Application | Main Distribution Board (MDB), primary power distribution | Sub-distribution, final circuits, tenant distribution |
| Metering | Full revenue/check metering as standard | Sub-metering only not revenue grade |
| Maintenance | Live maintenance possible (Form 4B) with isolation of individual units | Full de-energisation required for most work |
| Position in hierarchy | Nearest to transformer secondary highest in distribution hierarchy | Downstream of MDB or SMDB serves final loads |
In EAMFCO's distribution hierarchy for Saudi projects: the transformer secondary feeds the Main Distribution Board (MDB) - a switchboard. The MDB feeds Sub-Main Distribution Boards (SMDBs) - which may be switchboards or large panelboards. SMDBs then feed Final Distribution Boards (FDBs) - panelboards serving individual floors, zones, or process areas.
IEC Compliance Standards for Low Voltage Switchboards
IEC 61439-1 is the overarching standard for all low voltage switchgear and controlgear assemblies. It defines verification requirements that the manufacturer must meet for the complete assembly not just individual components. For Saudi Arabia, compliance with IEC 61439-1 and its sub-parts is mandatory on all projects procured by SEC, Saudi Aramco, NWC, and public sector infrastructure programmes.
| Standard | Scope |
|---|---|
| IEC 61439-1 | General rules definitions, electrical characteristics, temperature rise limits, dielectric properties, short circuit withstand, mechanical operation, degree of protection |
| IEC 61439-2 | Specific requirements for power switchgear and controlgear assemblies (PSC-assemblies) applies directly to LV switchboards |
| IEC 60947-2 | Low voltage circuit breakers the standard governing ACBs and MCCBs installed in the switchboard |
| IEC 60529 | IP degree of protection classification referenced for enclosure specification |
| IEC 60364 | Electrical installations of buildings defines earthing system (TN-S, TT) requirements that the switchboard neutral and earth arrangements must match |
| SASO | Saudi Standards, Metrology and Quality Organization mandatory certification for electrical equipment installed in Saudi Arabia |
Verification under IEC 61439-1 covers temperature rise (confirmed by test or calculation), short circuit withstand (confirmed by test or comparison with type-tested reference design), dielectric strength, mechanical endurance, and IP rating. EAMFCO LV switchboards are designed in accordance with IEC 61439-1 with segregation available up to Form 4B and IP ratings to IP65.
Where LV Switchboards Are Used in Saudi Arabia
Data Centres
Hyperscale and colocation data centres require switchboards with highest reliability: Form 4B segregation, dual bus arrangements with bus-coupler ACBs, and fast fault discrimination. EAMFCO supplied LV switchgear and switchboards for Shovelnose, Stingray, Edgnex, and STC data centres in Saudi Arabia.
Industrial Plants
Petrochemical, manufacturing, food processing, and fabrication facilities use switchboards as main distribution points, stepping down transformer output to MCCs, sub-boards, and large motors. Ratings of 2,500–6,300A are common for plants with 2–5 MVA transformer banks.
Commercial Buildings & Hotels
High-rise towers, hotels, and shopping malls use switchboards as building main distribution boards, with section boards per floor or zone. EAMFCO supplied LV switchgear for Al Salam Hotel and Taazeez Tower projects.
Water & Infrastructure
Pump stations, desalination facilities, and water treatment plants use switchboards rated for continuous heavy motor loads with high short circuit levels from stiff utility supplies.
Frequently Asked Questions
Q: What is the rated current of a low voltage switchboard?
A: LV switchboards range from 400A for small commercial installations to 6,300A for large industrial main distribution boards. The rated current corresponds to the busbar continuous current rating and is determined by maximum demand load plus a growth contingency. EAMFCO manufactures LV switchboards up to 6,300A per IEC 61439-1.
Q: What is the difference between Form 1, Form 2, Form 3, and Form 4 segregation?
A: IEC 61439 segregation forms define internal separation between busbars, functional units, and terminal compartments. Form 1 has no segregation. Form 2 separates busbars from functional units. Form 3 additionally separates functional units from each other. Form 4B provides the highest level all units and terminals individually enclosed allowing maintenance on one unit without exposing adjacent live components. Form 4B is standard for data centres, hospitals, and critical process plants in Saudi Arabia.
Q: What IP rating should a switchboard have for a Saudi industrial installation?
A: Indoor, air-conditioned electrical rooms: IP41 or IP43 minimum. Dusty industrial environments fabrication yards, cement, petrochemical: IP54. Outdoor or sand-exposed installations: IP55 or IP65. EAMFCO LV switchboards are available in IP43, IP55, and IP65 configurations.
Q: What does IEC 61439-1 compliance mean for a switchboard?
A: IEC 61439-1 defines verification requirements for the complete assembly temperature rise limits, dielectric strength, short circuit withstand, mechanical operation, and degree of protection. Compliance may be verified by type testing or by design calculation. For projects procured by Saudi Aramco, NWC, or SEC, IEC 61439-1 compliance is a mandatory contractual requirement.
EAMFCO - IEC 61439-1 Compliant LV Switchboards for Saudi Projects
EAMFCO manufactures custom-engineered low voltage switchboards rated up to 6,300A with Form 4B segregation, IP65 protection, and full factory testing for industrial plants, data centres, hospitals, and infrastructure projects across Saudi Arabia. Continue reading: