Commercial electrical wiring and how it compares to residential

We’re experts in all commercial electrical installations. We discuss how it commericial electrical wiring compares to residential.

Commercial electrical wiring and how it compares to residential


The difference between residential and commercial electrical wiring can cause confusion. How different can it be? Why do I need to pay out for a commercial electrical contractor?

The fact is that there are significant differences between the two. From the process of design to installation, and the laws that apply, it takes expert knowledge to complete commercial electrical installations. It requires expertise above and beyond residential electrical know-how.

Here we are going to explain exactly how the two are different and why you need a professional commercial electrical contractor for your business installations.


Chain of command in residential electrical wiring

There are few people in the chain of command when it comes to wiring a home. As a homeowner, you contact an electrician, explain the situation, and they do the job. It is a simple two-person chain.

Electrical load in residential electrical wiring

The electrical loads of home appliances are simple. Electrical loads in the home come in the form of lightbulbs, kettles, and dishwashers, for example. There is no heavy machinery, unusual voltage requirements, or complex electrical systems. This makes a difference in how contractors design a system.

Single-phase power

Almost all homes and private residences will use single-phase power (230V). Single-phase power is used in places that do not require a lot of energy. Think of the energy used in the home of a family of four compared to a huge factory operating dozens of machines 24-hours a day.

The cables in a single-phase power system only need to have three wires to supply circuits. The two wires consist of a live wire, a neutral wire and an earth wire. The earth wire being for cable and circuit protection.

A single-phase electrical installation in a domestic property is generally either 63A, 80A or 100A.


Chain of command in commercial electrical wiring

Unlike residential electrics, commercial electrical wiring design goes through many more people. When designing a commercial building, there will likely be an architect involved, for example. There will also be builders ensuring building regulations are followed correctly, and so on. In short, there are more steps – and more people – involved in commercial electrical wiring. The electrical contractor needs to communicate and work with the whole chain.

Accessibility in commercial electrical wiring

Commercial electrical wiring needs to be accessible. In your home, most wiring will be hidden – you will only see your sockets and fuse box. However, in a commercial property, the wiring needs to be easily accessible for maintenance, repair and shut-off. This means a different installation design. Contractors need to take these additional requirements into account to ensure the safety of anyone on the site, as more wiring is exposed.

Electrical load in commercial electrical wiring

In commercial properties, there are more purposes for energy than in the home. Different types of machinery have different functions – using motors, cooling elements, and alarms, for example. These systems use more power, which means, once again, there must be a difference in the system design.

Three-phase power

Commercial electrical wiring generally uses three-phase power instead of single-phase power. In simple terms, this means cables have four or five wires instead of only two. This consists of three live cables, a neutral cable and an earth cable. This means more current can be distributed to circuits supplying enough power to operate machinery and equipment in the factory or workplace that require it. The power delivery of energy in a three-phase power system is a balanced load and much more efficient than in single-phase ones. In fact, some three phase items of equipment are so balanced that a neutral cable is not required.


Wiring symbols show the location of component parts in electrical design diagrams detailing electrical systems.

There are far more commercial electrical wiring symbols than residential. Beyond the commercial wiring basics, there are symbols for things such as:

○ Elevators and escalators

○ Fire alarm sprinkler systems

○ Walk-in freezers

○ Automatic doors

These are things you wouldn’t generally see in the average home. A commercial electrical contractor can interpret these wiring symbols and design electrical systems to properly balance power and support their operation.


Interpreting electrical wiring symbols takes more than simple common sense. Look at this diagram, could you figure it out?

Image source:


All electricians – both residential and commercial need industry-recognised qualifications and must know their way around a circuit. However, commercial electricians and domestic contractors will have different responsibilities, knowledge and experience.

The qualifications and training of contractors

To qualify as an electrician you need an industry-recognised Level 3 qualification, such as:

○ Level 3 NVQ diploma in Electrotechnical Services (Electrical Maintenance)

○ Level 3 NVQ diploma in Installing Electrotechnical Systems & Equipment (Buildings, Structure and the Environment)

○ Level 3 diploma in Electrical Installations (Buildings and Structures) if part of an apprenticeship.

The qualifications above are usually completed while working. However, if you are interested in specialist areas, such as solar energy, you will require additional training.

Another training route is to complete an Electrotechnical Apprenticeship.

Commercial Electricians are legally obliged to comply with The Electricity at Work Regulations 1989 which governs the maintenance of electrical systems in the workplace and will need to be appropriately trained, depending on the appliances or machinery involved.

All electricians must be well-informed in the appropriate standards for the setting they are working in.


At Fusion, we’re experts in all commercial electrical installations.

Our services include commercial electrical installations, electrical maintenance services, and data cabling installation. We’ve worked to install commercial installations in prisons, hospitals, and factories. We’ve even worked on conservation projects as specialists in solar power. So if you’re looking for a commercial electrical wiring job done right, contact us today.

Subscribe to be kept up to date with the latest news.