About this service
A three-phase installation distributes load across three alternating phases and is common for larger commercial supplies, motors, plant and high-power equipment. New work may include distribution boards, isolators, machinery supplies, EV charging or phase-balanced single-phase circuits.
Design must consider load per phase, prospective fault current, protective-device breaking capacity, cable rating, phase sequence, neutral currents and the equipment manufacturer’s requirements.
Common problems we help with
New equipment requires three phase
The premises may have a three-phase intake but no suitable local distribution or spare capacity.
Loads are poorly balanced
Excessive single-phase load on one phase can limit capacity and affect voltage.
Incorrect phase sequence
Motors and rotating equipment can run in the wrong direction.
Protective equipment is underrated
Fault level and equipment rating must match the supply and distribution point.
How we carry out the work
Confirm supply and equipment data
We record voltage, load, starting current, fault data, cable route and control requirements.
Design protection and distribution
Phase balance, cable, board, isolation and coordination are calculated.
Install and verify phase performance
Continuity, insulation, phase sequence, fault protection and equipment connection are tested.
What is normally included?
- Initial discussion about the property, symptoms, priorities and timescale
- Assessment of the relevant circuit, equipment, access and existing protection
- A written scope for the proposed three-phase electrical installation work
- The agreed installation or repair work, with disruption kept to a reasonable minimum
- Inspection, electrical testing and appropriate handover documentation
Before the work starts
- Operational loads, critical equipment and permitted shutdown windows
- Existing drawings, circuit schedules and maintenance records
- Access, permits, occupied areas and coordination with site management
- Future capacity, maintainability and business-continuity requirements
What affects the price?
The price depends on the existing installation and the amount of work required. For three-phase electrical installation, the main factors normally include:
- Load, circuit and distribution complexity
- Containment, access equipment and working restrictions
- Phasing, temporary supplies and out-of-hours work
- Testing, documentation and coordination with specialist equipment
Testing, certificates and handover
Once the installation work is complete, we inspect and test it and provide the records that apply to the job.
- Updated labels, schedules and relevant drawings
- Installation or test certification
- Operating and isolation information
- A documented list of agreed variations and remaining recommendations
Three-Phase Electrical Installation questions
Can you convert single phase to three phase?
The network operator controls the incoming supply. We can assess requirements and install customer-side equipment after an appropriate supply is available.
Is three phase always more powerful?
It supports different distribution and equipment arrangements, but usable capacity depends on the actual supply and design.
Why does phase sequence matter?
It determines rotation direction for three-phase motors and some machinery.
Booking the work
What happens after you contact us
1. Discuss the job
Tell us about the property, the symptoms or the result you want. Photographs and model numbers are often helpful.
2. Inspect and quote
We check the relevant installation and give you a written quotation showing what is included.
3. Complete and test
We carry out the agreed work, verify it electrically and explain any controls, labels or certificates at handover.