Low voltage (LV) switchgear handles power at up to 1,000 V AC and distributes it inside a facility, while medium voltage (MV) switchgear handles power above 1 kV, typically at the point where the utility supply arrives or where a large site distributes power internally. Most industrial projects need both: MV equipment brings power in and steps it down, and LV equipment takes it from there to motors, process lines and buildings. This guide from Paklink LLC explains how the two differ, where each belongs, and how to decide what your project needs. If you are looking for a partner on the LV side, see our LV switchgear contractor services in Dubai.
What is the difference between LV and MV switchgear?
The core difference is voltage, and voltage changes almost everything else: the insulation, the size of the equipment, the standards it is built to, the way it is switched, and the safety distances around it. Switchgear is the combined set of switching devices, protection and control that isolates faults and lets operators connect or disconnect parts of the power system safely. LV and MV switchgear do the same job at different voltage levels.
| Feature | LV switchgear | MV switchgear |
|---|---|---|
| Voltage range | Up to 1,000 V AC (415 V three-phase is the usual site voltage in Dubai) | Above 1 kV, commonly 11 kV in Dubai distribution |
| Main standard | IEC 61439 series for assemblies, IEC 60947 for devices | IEC 62271 series |
| Typical devices | Air circuit breakers, moulded case circuit breakers, contactors, fuses | Vacuum circuit breakers, load break switches, earthing switches, protection relays |
| Typical location | Main LV room, MCC rooms, distribution rooms | Substation, incoming supply room, ring main units |
| Insulation | Air and solid insulation within the panel | Air insulation or gas insulation (GIS), with vacuum interrupters in many breakers |
| Main role | Distribute power to motors, buildings and process loads | Receive utility supply, distribute at high capacity, feed transformers |
| Typical equipment size | Compact, floor-standing panels | Larger, with greater clearances and heavier components |
The voltage bands above follow general IEC practice. Always check the exact definitions and limits in the project specification and with the utility, because local rules and client standards can set their own boundaries.
Where does each type sit in an industrial power system?
MV switchgear sits upstream and LV switchgear sits downstream, with a transformer between them. In a typical industrial site the path looks like this:
- The utility supplies power at medium voltage, commonly 11 kV in Dubai.
- MV switchgear receives it, protects the incoming supply and distributes it to one or more transformers.
- Transformers step the voltage down to 415 V.
- LV switchgear receives that supply and splits it into feeders.
- Motor control centers (MCCs) and distribution boards take power to motors, process equipment, lighting and small power.
A package substation combines steps 2 to 4 in a single factory-assembled unit, which is why it is popular when space or programmed time is tight. Smaller commercial buildings often receive supply that is already stepped down, and need only the LV part of the chain.
When does a project need MV switchgear?
A project needs MV switchgear when the site takes supply at medium voltage or distributes power internally at medium voltage. The common triggers are:
- Large connected load: when demand is high enough that the utility supplies the site at medium voltage, you need MV equipment at the incoming point.
- A dedicated on-site substation: a site with its own transformers needs MV switchgear to protect and switch them.
- Large motors: some very large motors run at medium voltage to reduce current and cable size.
- Long distances across a large site: distributing at medium voltage reduces losses and cable cost compared with running large LV feeders.
If none of these apply, your project probably needs LV switchgear only. The incoming supply arrangement is agreed with the utility, so confirm it early. It affects room layout, cable routes and programmed.
What standards apply to LV and MV switchgear?
LV switchgear assemblies are covered by the IEC 61439 series, and the devices inside them by IEC 60947. MV switchgear and controlgear fall under the IEC 62271 series. You can browse the standards and their scope on the IEC website.
Two practical points follow from this:
- Ask for verification evidence. For an LV assembly, that means design verification to IEC 61439 and routine test records. For MV equipment, it means type test reports and routine test certificates for the specific design.
- Check the arc fault rating. An internal arc is a fault inside the enclosure that releases large amounts of energy. Both LV and MV equipment can be tested and classified for it. The classification tells you how well the enclosure protects people standing nearby, which matters in rooms that operators enter.
How do you choose between air-insulated and gas-insulated MV switchgear?
Air-insulated switchgear (AIS) uses air as the main insulation between live parts, while gas-insulated switchgear (GIS) encloses live parts in a sealed compartment filled with insulating gas. The choice mostly comes down to space, environment and lifecycle cost.
| Factor | Air-insulated (AIS) | Gas-insulated (GIS) |
|---|---|---|
| Footprint | Larger | Much more compact |
| Exposure to dust, humidity and salt | More exposed | Live parts sealed inside |
| Maintenance | Easier access, more routine upkeep | Less routine upkeep, specialist handling |
| Upfront cost | Generally lower | Generally higher |
| Best fit | Sites with space and a controlled switch room | Tight rooms, harsh or coastal environments |
Gas choices and handling rules vary between manufacturers and are changing as the industry moves away from some traditional gases, so ask your supplier what the equipment uses and what the end-of-life and leak-management arrangements are.
What should you ask your electrical contractor?
A good contractor can explain the LV and MV decisions in plain language and back them with documents. Ask these questions before awarding the work:
- What is the supply voltage at the site, and has the incoming arrangement been agreed with the utility?
- Which standards will the LV and MV equipment be built and tested to, and can you see the evidence?
- What form of internal separation is proposed for the LV assemblies, and why?
- What is the arc fault classification of the equipment?
- How will the equipment cope with Dubai’s heat, dust and humidity?
- What spare capacity is built in for future expansion?
- Who commissions the system, and what tests are carried out on site?
Vague answers to these questions usually mean the design work has not been done yet.
What mistakes do projects commonly make?
Most switchgear problems start at specification stage, not in the equipment itself. Four mistakes appear again and again:
- Specifying MV when the site does not need it, which adds cost, space and maintenance obligations for no benefit.
- Under-sizing the LV room, leaving no space for extra panels, maintenance access or the clearances that safety rules require.
- Ignoring ambient conditions, so equipment is rated for mild weather and runs hot in summer.
- Leaving utility coordination until late, which delays energization when the supply arrangement turns out to differ from what the design assumed.
Need help specifying switchgear for your project?
If you are planning an industrial power system and want a second opinion on LV and MV requirements, talk to the team at Paklink LLC. You can also read about our electrical contracting services to see the scope we cover.
Frequently asked questions
What voltage is low voltage switchgear? Low voltage switchgear is generally defined as equipment for up to 1,000 V AC. In Dubai, most industrial site distribution runs at 415 V three-phase.
What voltage is medium voltage switchgear? Medium voltage switchgear covers voltages above 1 kV. In Dubai, the common distribution voltage is 11 kV.
Do I need both LV and MV switchgear? Large industrial sites with their own substation usually do. Smaller sites supplied at low voltage typically need LV switchgear only. Confirm the supply arrangement with the utility.
What standards cover LV and MV switchgear? IEC 61439 covers LV switchgear assemblies and IEC 60947 covers LV devices. IEC 62271 covers medium voltage switchgear and control gear.
What is the difference between a transformer and switchgear? A transformer changes voltage levels. Switchgear switches, protects and isolates circuits. They work together in a substation but do different jobs.
