Electrical switchboards: The buyer’s guide to design, installation, and maintenance

Working on a power distribution project means understanding electrical switchboards. These systems control where electricity goes, how it's protected, and how it's maintained across a building or facility. Whether you're designing the system, specifying equipment, or troubleshooting in the field, getting the details right can prevent major issues like equipment failure or fire hazards.

This guide is for electrical distributors, manufacturer reps, and engineering teams who manage power infrastructure. We'll walk through everything you need to know about switchboards: what they do, how they work, how to read their diagrams, and how to maintain them.

Already know what you need? Giga Energy offers a complete line of UL 891 low voltage switchboards with fast lead times and great service, shipping from our factory in Long Beach, CA.

What is an electrical switchboard?

A switchboard is a component of an electrical distribution system that takes electricity from one or more power sources and sends it to the different devices that need it. Think of it as a traffic controller for electricity inside a building or facility. It ensures that the right amount of power flows to the right place, safely and reliably.

Electrical switchboards are housed in metal cabinets filled with electrical components including breakers, fuses, and bus bars. These components help control where the power goes, how much goes there, and what happens if something goes wrong. They also come in many sizes, from small residential panels to massive industrial setups.

What do electrical switchboards do?

Electrical switchboards are more than just boxes that route power.

Protect equipment and people

Switchboard priorities are, in order:

1. Protect human beings.
2. Protect downstream equipment.
3. Distribute power safely and adequately.

Electrical problems like short circuits or overloads can happen without warning. Switchboards come equipped with circuit breakers or fuses that automatically shut down affected circuits when something goes wrong. This prevents damage to expensive equipment, and most importantly, helps reduce the risk of fire or electrical shock.

Direct power where it’s needed

The main job of a switchboard is to route electricity from the source, like a utility line, generator, or solar array, to the right parts of a building or site. It divides power into circuits that feed lighting, machinery, outlets, and everything in between. Without this routing, electricity would have nowhere safe to go.

Offer easy control

Switchboards make it simple to manage different parts of your system. Want to shut off power to a specific area for maintenance? Flip a switch. Need to isolate a piece of equipment during an emergency? The controls are right there. This hands-on access adds flexibility and improves safety.

Monitor system health

Most modern electrical switchboards include built-in meters and gauges that show real-time data like voltage, current, and frequency. These readings can help spot issues before they become serious, like a sudden voltage drop that hints at a failing transformer or an overload that needs attention.

Types of electrical switchboards

Not all electrical switchboards are the same. The right one depends on how much power you’re managing, what kind of equipment you’re running, and the layout of your system. 

Main switchboards

These are the heavy lifters. Main switchboards take in a large amount of electricity from a utility or generator and distribute it to smaller systems. They’re typically found at the service entrance of a building or facility and include the main protective devices for the entire system. This construction must conform to UL891 in the United States.

Distribution boards

Once power reaches the main switchboard, it usually gets passed along to one or more distribution boards. These boards break the power into smaller, more specific circuits, like those for HVAC systems, lighting, or elevators. They make it easier to manage and isolate sections of the electrical system. This construction typically conforms to UL67, but can be built to conform to UL891 in the United States.

Panelboards

Common in homes and small commercial spaces, panelboards are compact versions of distribution boards. They handle lower voltages and are designed for simpler layouts. If you’ve ever flipped a breaker in your house, you’ve used a panelboard. This construction must conform to UL67 in the United States.

Motor Control Centers (MCCs)

MCCs are built for environments with lots of electric motors: factories, water treatment plants, or processing facilities, for example. These switchboards do more than distribute power. They also control motor functions, including speed and direction, and include built-in protection for each motor.

Switchgear assemblies

When you’re dealing with high-voltage industrial or utility applications, standard switchboards aren’t enough. That’s where switchgear comes in. These assemblies are designed for serious power loads and offer advanced features like remote switching, arc-flash protection, and system automation. This construction generally conforms to UL1558 for the United States for 1000V systems and under.

How do electrical switchboards work?

At their core, electrical switchboards manage how electricity enters a system, gets divided into circuits, and reaches the equipment that needs it. While the layout can vary depending on the setup, the basic process is the same in most systems.

Let’s walk through how power flows through a typical switchboard:

1. Power comes in

Electricity usually enters the switchboard from a utility company, an on-site generator, or a backup power source. This incoming power is high in voltage and needs to be carefully managed to prevent damage or safety issues.

2. The main breaker controls the flow

Before anything else happens, the power hits a main breaker or disconnect switch. This device acts like a gate, and it can shut off the entire system if needed. It’s essential for maintenance, emergencies, or quickly isolating the switchboard from the rest of the electrical system.

3. Bus bars move the power internally

Once power passes through the main breaker, it flows along thick metal conductors called bus bars. These bars distribute the electricity throughout the switchboard. They’re built to handle large amounts of current and help keep the system organized and compact.

4. Circuit breakers divide and protect

From the bus bars, power moves into circuit breakers or fuses. Each one routes electricity to a different circuit. For example, one breaker might serve the lighting system, while another powers machinery or HVAC. These protective devices also shut off automatically if there’s too much current, helping prevent damage or fires.

5. Power goes out to the right places

Finally, the switchboard sends electricity out to where it’s needed (equipment, lighting, outlets, or other distribution points). This step completes the journey from the power source to the point of use.

Inside the Box: Key Components Explained

Knowing what’s inside a switchboard can help you troubleshoot issues, plan upgrades, or simply make better design choices. Each part plays a specific role in keeping your electrical system safe, organized, and running smoothly.

Here’s a breakdown of the core components you’ll find in most electrical switchboards:

Bus bars: The power highways

Bus bars are solid metal strips usually made of copper or aluminum that carry large amounts of current throughout the switchboard. Think of them as the main highways that deliver electricity to different areas of the system. Their size and shape matter: they need to be rated correctly to handle the full electrical load without overheating or creating resistance.

Circuit breakers: Reusable protection

Circuit breakers are the frontline defense against electrical problems. If too much current flows through a circuit, due to a short circuit or overload, the breaker will “trip” and shut off power to that section. This helps prevent damage to equipment and lowers the risk of electrical fires. The breaker may be reset after resolving the underlying issue, making it a reusable safety feature.

Fuses: One-time safety devices

Fuses do the same job as circuit breakers but in a simpler, one-time-use form. When too much current flows, the fuse blows and/or melts to stop the flow of electricity. Fuses are common in older systems or applications where a fast response is needed. Once blown, they must be replaced before the circuit can be used again.

Protective relays: Smart monitoring for larger systems

In bigger or more complex installations, protective relays add an extra layer of control. These devices constantly monitor the system for abnormal conditions, like undervoltage, overcurrent, or frequency shifts. When something goes wrong, the relay sends a signal to a breaker to trip, offering fast and precise protection for high-value equipment.

Grounding systems: Safe paths for stray current

Every switchboard needs a way to safely redirect stray electricity. That’s where the grounding system comes in. It provides a low-resistance path for unwanted current, like what might result from a fault or lightning strike, to flow safely into the earth. This helps reduce the risk of electric shock, fire, or damage to equipment.

Meters and gauges: Real-time feedback

Meters and gauges show what’s going on inside the system at any given moment. You might see readings for voltage, current, frequency, or load levels. Some systems use digital displays, while others rely on analog dials. Either way, these tools help operators catch problems early and monitor performance over time.

Low voltage vs. medium voltage: What’s the difference?

When you're working with electrical systems, one of the first things to figure out is the voltage level. Why? Because voltage affects everything: from the size of your equipment to how it’s installed and maintained. Two common categories you’ll hear about are low voltage and medium voltage. Understanding the difference helps you choose the right switchboard for your project.

Low voltage (Below 1,000 volts)

Low-voltage switchboards are the most common type. You’ll see them in homes, office buildings, small shops, and light industrial settings. These systems usually run at 120V, 240V, or 480V, depending on the application.

They’re easier to work with, take up less space, and are simpler to install and maintain. In most cases, standard safety gear is enough to service them, and the equipment doesn’t need as much insulation or clearance. If you’re working on a school, an apartment building, or a small warehouse, you’re most likely dealing with low voltage.

Medium voltage (1,000–35,000 volts)

Medium-voltage systems are used in places that need a lot of power, like factories, hospitals, large data centers, and utility substations. These systems move power over longer distances and feed energy-hungry equipment.

Because of the higher voltage, these switchboards need more insulation, more space around them, and special safety precautions. You can’t just tuck one into a utility closet, they usually go in their own dedicated rooms or outdoor enclosures. Maintenance and installation need to be done by trained technicians with the right protective equipment.

Understanding ratings and certifications

When you’re looking at switchboard specs, you’ll usually see a few standard ratings that will tell you how the switchboard will perform under specific conditions.

• Voltage rating: This tells you the maximum voltage the switchboard is designed to handle. It must match, or ideally exceed, the voltage in your system to avoid overheating, insulation failure, or other risks.
• Amperage rating: Also known as the continuous current rating, this rating shows how much electrical current the board can carry over time without overheating. It’s important for sizing the system based on real-world demand.
• Short-circuit current rating (SCCR): A number that tells you the maximum fault current the switchboard can safely withstand during a short circuit. If the fault current in your system exceeds the SCCR, the switchboard could fail dangerously. Matching this rating to your system’s potential fault current is critical for safety.

In addition to performance ratings, switchboards also need to meet recognized safety and construction standards, and there are a few certifications that prove this.

• UL 891: Common for low-voltage switchboards
• UL 1558: Used for metal-enclosed switchgear
• ANSI/NEMA standards: Cover a wide range of design and safety requirements

Learn more: Understanding switchboard certifications

Where are switchboards used?

Switchboards show up almost everywhere electricity is used on a large scale. But how they’re built and what they’re expected to handle can vary a lot depending on the setting. 

• Factories and industrial facilities: In manufacturing plants or processing facilities, switchboards need to manage large amounts of power to run heavy-duty machinery. These systems often include motor control centers (MCCs), high-capacity bus bars, and rugged enclosures to handle harsh conditions like heat, dust, and vibration. There's also a strong focus on safety features and downtime prevention, since power loss can halt entire production lines.
• Offices and commercial buildings: In office buildings, power demand is spread across lighting, HVAC systems, computers, elevators, and plug loads. Switchboards here focus on detailed distribution, often through panelboards and sub-distribution boards, to manage multiple floors and tenant spaces. Flexibility is also important if we consider that layouts often change over time with renovations or tenant turnover.
• Hospitals and healthcare facilities: These setups typically include redundant power systems, like dual utility feeds and backup generators, to ensure life-support equipment and emergency systems stay online during an outage. Switchboards in these environments often integrate with automatic transfer switches (ATS) and have extremely strict compliance requirements.
• Schools and educational campuses: Schools need switchboards that are safe, scalable, and easy to maintain. From classrooms and gyms to labs and cafeterias, the power demands vary throughout the day and across campus. Systems must meet strict electrical codes, especially when it comes to student safety and fire protection. 
• Substations and utility systems: Substations use large, rugged switchgear assemblies to manage high-voltage electricity coming from transmission lines. These switchboards step down power for local use and include advanced protection features to handle fault conditions, weather events, and grid fluctuations. They’re built to last and are usually maintained by utility companies or trained technicians.

How to read and interpret schematics

Schematics are detailed drawings that show how an electrical system is designed and connected. Think of them as the blueprint for your switchboard: They map out every component and connection so electricians and engineers can understand how power flows and how everything fits together. 

These resources can look complex at first, because they are. But the truth is that learning how to read them unlocks a clear view of the entire system’s structure and function and helps professionals approach electrical systems with better resources. Some of the main schematics you might find are: 

Single-line diagrams

Single-line diagrams simplify complex electrical systems by showing the flow of electricity with just one line. Instead of drawing every wire, these diagrams use symbols to represent components like transformers, breakers, and bus bars, which makes it a bit easier.

Depending on the industry, single-line diagrams may be referred to as one-line diagrams, but these terms refer to the same thing.

Load and panel schedules

Load and panel schedules break down all the circuits in the system, so they are more detailed than single-line diagrams. They list each circuit’s purpose, such as lighting or HVAC, and show the expected current load for each.

Grounding paths

These lines show where and how the system is grounded.

Reading schematics helps during installation, inspection, and maintenance.

Specifying and sourcing the right switchboard

When choosing a switchboard, you’ll want to look at:

• How much power does your facility need (now and in the future)?
• How many circuits do you need to manage?
• How much physical space do you have for the board?
• Does the board meet your local code and utility requirements?
• What is the application?
• What are the incoming and outgoing connections?
• What other components are required outside of breakers?

Some projects are delayed because of long lead times or last-minute design changes. Planning ahead helps avoid these issues.

Learn more: Specifying switchboards for a project

Installation: Avoiding common mistakes

There are a lot of mistakes that can take place during the setup process, and they can lead to expensive problems. Here are a few things to pay attention to:

• Using components that can’t handle fault currents
• Not leaving enough space for ventilation or service access
• Under-tightening bus bar connections
• Using a breaker with the incorrect rating for the desired load

Working with experienced professionals and double-checking specs can prevent most of these issues.

Maintenance and keeping the system running

Just like any other part of your electrical system, switchboards need regular attention to stay safe, efficient, and reliable. Over time, even well-installed equipment can develop problems, but a proactive maintenance routine helps catch small issues before they lead to big failures or costly downtime.

Thermal imaging

Loose connections and overloaded circuits generate heat long before they fail. Thermal imaging allows you to scan your switchboard while it’s live and pinpoint these "hotspots" in real time. Identifying heat patterns early can help prevent component failure and improve system reliability without having to shut things down.

Breaker testing

Over time, circuit breakers can wear out or become sluggish. Routine testing ensures the breaker continues to function properly and will work as designed during overloads or short circuit events.

Cleaning

Switchboard enclosures need to be cleaned periodically, especially in industrial or outdoor environments. Dust, grime, and moisture can lead to tracking (where electricity follows unwanted paths), corrosion on metal components, or even full-blown short circuits.

Re-torquing

Connections can loosen over time and need to be re-tightened to spec.

Common failures include rust, worn contacts, and bad seals. A proactive maintenance plan helps avoid unplanned downtime.

Routine maintenance should be conducted at least once a year. This includes testing, cleaning, and re-torquing.

Planning for the future

Even if your system works perfectly now, future demands may change that. More people, more machines, and new technologies (like EV chargers or battery systems) can add unexpected loads.

Good planning means leaving room in your switchboard, both physically and electrically, for future changes. Modular designs can help by letting you add sections or circuits later on.

Learn more: Why is the traditional way of sourcing switchboards broken?

Have questions about switchboards or looking to purchase?

Switchboard systems may look complicated, but this guide should help you understand the basics. If you follow all the links in this guide, you will be far more equipped to make a decision.

If you need some expert support to source your next electrical switchboard, or even if you just have questions about what your needs may be, we are here to help. Reach out to our team and we’ll figure it out together.