Direct Answer
A low voltage switchboard (LV switchboard) is an IEC 61439-compliant assembly rated up to 1,000V AC that distributes power to outgoing circuits through protective devices. Medium voltage switchgear (MV switchgear) is an IEC 62271-compliant assembly rated above 1,000V typically 12 kV, 17.5 kV, or 36 kV that switches, protects, and controls the MV network and transformer feeders. They operate at different voltage levels, serve different functions, and are never interchangeable.
Side-by-Side Comparison
| Parameter | LV Switchboard | MV Switchgear |
|---|---|---|
| Voltage range | Up to 1,000V AC (typically 400V in Saudi Arabia) | Above 1,000V AC typically 12 kV, 17.5 kV, 36 kV |
| Governing standard | IEC 61439-1 / IEC 61439-2 | IEC 62271-200 (metal-enclosed) / IEC 62271-202 (package substations) |
| Primary function | Power distribution receives transformer output, feeds outgoing circuits | Power switching, protection, and control of MV network and transformer feeders |
| Main device | Air Circuit Breaker (ACB) or MCCB up to 6,300A | Vacuum Circuit Breaker (VCB) or SF₆ insulated switch |
| Busbar material | Copper or aluminium tinned, rated for rated current | Copper rated for MV fault current withstand (kA) |
| Protection device | Thermal-magnetic or electronic trip unit (LSIG) | Numerical protection relay (overcurrent, earth fault, differential) |
| Insulation medium | Air open construction within rated enclosure | Air, SF₆ gas, or solid insulation (GIS/GIL) |
| Personnel access | Possible with correct PPE and isolation (Form 4B) | Requires full de-energisation or interlocked access |
| Cost (relative) | Lower mass-produced components | Higher specialised MV-rated components |
| Typical Saudi application | MDB, SMDB, MCC inside buildings and plant rooms | RMU, MV switchboard inside substation or switchroom |
| Manufacturer type | LV switchgear manufacturer | MV switchgear specialist or OEM |
| Installation position | Downstream of MV/LV transformer | Upstream of transformer on MV network |
Where Each Is Used in an Industrial Facility
A complete Saudi industrial facility's power distribution system uses both at different points in the power flow. Understanding their position in the single-line diagram (SLD) is the clearest way to distinguish their roles:
The MV switchgear sits upstream of the transformer operating at 13.8 kV or 33 kV. The LV switchboard sits downstream - operating at 400V. They are connected through the transformer and are separated by both voltage level and physical location (MV switchgear typically in a dedicated MV room or kiosk; LV switchboard in the main electrical room).
Common Confusion Among Engineers and Contractors
The terms "switchboard" and "switchgear" are misused regularly in Saudi project specifications, tender documents, and on site. The following misconceptions cause incorrect procurement, specification errors, and budget overruns:
Common Misconception
"Switchgear" is used in BOQs to describe LV distribution boards, MCCs, and main distribution panels indiscriminately regardless of voltage level.
Technical Reality
IEC 62271 defines "switchgear" as MV/HV equipment operating above 1,000V. LV equipment below 1,000V is "switchgear and controlgear assemblies" per IEC 61439. Using "switchgear" for LV boards in a tender BOQ results in ambiguous specifications that different suppliers interpret differently leading to non-comparable quotations.
Common Misconception
"The switchboard and the RMU are both switchgear they do the same job at different voltages."
Technical Reality
An RMU (Ring Main Unit) switches, isolates, and protects the MV ring network and transformer feeder at 13.8 kV or 33 kV. An LV switchboard distributes 400V power to outgoing circuits. They perform fundamentally different functions, are built to different standards (IEC 62271 vs IEC 61439), require different maintenance procedures, and are procured from different types of manufacturers.
Common Misconception
"We just need a switchboard skip the MV panel, the transformer is someone else's scope."
Technical Reality
The LV switchboard specification depends on the transformer. The busbar rating, incomer ACB trip unit settings, short circuit withstand current (kA), and CT ratios are all determined by the transformer kVA, impedance, and vector group. Specifying the LV switchboard without knowing the transformer parameters produces an incomplete specification that cannot be built correctly.
Real-World Industrial Examples from Saudi Arabia
| Project Type | MV Switchgear Used | LV Switchboard Used |
|---|---|---|
| Data Centre (Shovelnose, Stingray) | SF₆ RMU at 13.8 kV 2L+T configuration for SEC ring feed, with VCB transformer feeder | Main LV switchboards (MDB) up to 6,300A Form 4B, dual bus with bus-coupler ACB for N+1 resilience |
| Hotel / Commercial Tower (Al Salam, Taazeez) | Compact package substation RMU at 13.8 kV feeding building transformers | Floor distribution boards (SMDBs) fed from main LV switchboard in basement electrical room |
| Industrial Fabrication Yard (NPCC, Jubail Naval Base) | MV switchboards or RMUs at 13.8 kV for large multi-transformer installations | Large MDB switchboards at 3,200–6,300A feeding multiple MCCs and process distribution boards |
| Water Treatment Plant (Eastern Province, NWC) | RMU at 13.8 kV with protection relay for pump motor feeder discrimination | MCC-type LV switchboards feeding pump motor starters, with VSD interfaces |
Which One Should You Choose?
This question assumes a choice but in most Saudi industrial facilities, you need both. The correct question is: which type of LV switchboard is right for your application?
| Your Requirement | Specify This |
|---|---|
| Main incoming power distribution at 400V from transformer secondary | LV Switchboard (MDB) IEC 61439-2, rated current per load schedule + growth margin |
| Sub-distribution to building zones, floors, or process areas | LV Switchboard (SMDB) lower rated current, fewer feeders, simpler busbar |
| Motor starting and control for pumps, fans, compressors | Motor Control Centre (MCC) specialised LV switchboard with starter modules |
| Protection and switching of 13.8 kV or 33 kV incoming supply | MV Switchgear (RMU or MV switchboard) IEC 62271 |
| Critical installation requiring live maintenance capability | LV Switchboard with Form 4B segregation and draw-out functional units |
| Outdoor or harsh environment Saudi sand and heat | LV Switchboard with IP55 or IP65 and forced ventilation |
If your project specification uses the word "switchgear" without specifying a voltage level and IEC standard, it is ambiguous. A specification that reads "supply and install LV switchgear for the main distribution" should be clarified to "supply and install one (1) Low Voltage Main Distribution Board (MDB) to IEC 61439-1/2, rated [x]A, [x]kA fault withstand, Form [x] segregation, IP[x]" before issuing to suppliers.
Frequently Asked Questions
Q: Is a switchboard the same as switchgear?
A: In precise IEC terminology, no. Switchgear refers to MV/HV equipment operating above 1,000V governed by IEC 62271. A switchboard is an LV assembly rated up to 1,000V governed by IEC 61439. In everyday Saudi project usage, 'switchgear' is often informally applied to LV assemblies technically inaccurate but widely understood in context.
Q: What voltage does LV switchgear operate at?
A: Low voltage switchgear and controlgear assemblies per IEC 61439 are rated for voltages up to 1,000V AC. The standard Saudi LV system voltage is 400V three-phase at 50 Hz. Equipment above 1,000V AC is classified as medium or high voltage switchgear under IEC 62271.
Q: Do I need both switchgear and a switchboard in my facility?
A: Most Saudi industrial and commercial facilities require both. The MV switchgear RMU or MV switchboard receives the SEC supply at 13.8 kV or 33 kV and protects the transformer. The LV switchboard receives the transformer output at 400V and distributes it to facility loads. They are separate assemblies, different standards, different voltage levels working together as the complete power distribution system.
Q: Can EAMFCO supply both MV switchgear and LV switchboards for a project?
A: EAMFCO specialises in LV switchboards and controlgear assemblies per IEC 61439-1 Main Distribution Boards, SMDBs, MCCs, and panel boards. For MV switchgear requirements, EAMFCO integrates approved MV components as part of complete package substation assemblies.
EAMFCO Custom LV Switchboards for Saudi Industrial Projects
EAMFCO manufactures IEC 61439-1 compliant low voltage switchboards - MDBs, SMDBs, and bus-coupler arrangements rated up to 6,300A, with Form 4B segregation and IP65 protection for demanding Saudi industrial environments. Continue reading: