A building services electrical engineer designs the electrical systems that power, light and protect a building. On commercial and larger residential schemes they work alongside a mechanical engineer as part of an M&E team. Their designs cover everything from the main incoming supply and distribution boards through to individual lighting circuits, fire detection, emergency lighting and EV charging infrastructure. Unlike a site electrician, an electrical engineer produces the design specification and calculations; the installation is then carried out by a contractor working to that specification.
What they do
- Power distribution design - incoming supply, switchboards and sub-distribution
- Lighting design and specification including lux level calculations
- Fire alarm system design to BS 5839
- Emergency lighting layout and duration calculations
- EV chargepoint infrastructure design and load management
- Data and telecoms cabling design
- Earthing and bonding specification
- Energy metering strategy and sub-metering design
When you need one
A building services electrical engineer is needed on commercial projects, larger residential schemes, and any project where the electrical systems are too complex for a site electrician to design without engineering support.
Typical costs (UK, 2025)
| Job type | Typical cost |
|---|---|
| Electrical specification (small commercial) | £500 - £1,800 |
| Lighting design package | £600 - £2,500 |
| Fire alarm design | £400 - £1,200 |
| EV charging infrastructure design | £400 - £1,000 |
| Full electrical engineering package | £1,500 - £6,000+ |
| Hourly rate | £80 - £145 / hr |
Commercial and large residential projects are often quoted as a percentage of the electrical installation cost (typically 3-6% for design only). Always confirm site visits, revisions and tender support are included.
Qualifications to look for
The primary chartered qualification for electrical engineers. Confirms competence in power systems, protection and control, and building electrical design. Check at theiet.org.
The specialist membership for building services professionals. MCIBSE confirms competence in building electrical systems including lighting, power distribution and fire safety. Check at cibse.org.
The academic foundation for IET and CIBSE membership. MEng is the preferred route for Chartered Engineer status under IET.
How to find a reputable electrical engineer
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EV Chargepoint Cost Calculator Extension Cost Calculator New Build Cost CalculatorFrequently asked questions
What is the difference between an electrical engineer and an electrician?
An electrical engineer designs electrical systems at a high level - specifying cable sizes, protection coordination, load calculations and system layouts. An electrician installs the systems on site. On commercial projects you need both: an engineer to design and specify, and an electrician to install and certify. On domestic projects a Part P registered electrician can design and certify their own work.
Do I need an electrical engineer for a house extension?
No. For domestic extensions and alterations, a Part P registered electrician can design, install and certify the electrical work. A building services electrical engineer is needed on commercial fit-outs, large residential developments, and projects with complex power distribution, fire alarm design or EV charging infrastructure.
What is Part P?
Part P is the part of Building Regulations covering electrical safety in dwellings. Most domestic electrical work must be carried out by a competent person registered with an approved scheme such as NICEIC, NAPIT or SELECT. Registered electricians can self-certify their work; unregistered contractors must notify the local authority building control before starting notifiable work.