Electrical network design: stages and scope of the project

Article author: Volodymyr Ledok, Production Technical Director at LK Energy Group.
He oversees the engineering side of power supply projects and the manufacturing of LK Energy switchgear — NKU, KRU, KSO, KTP. Every day he sees both ends of the process: how a single-line diagram is born, and how the actual switchboard is then built from it at the plant in Odesa.

Electrical network design is the development of a set of technical documentation used to build or reconstruct a facility's power supply system: from obtaining technical conditions from the distribution system operator to the working drawings an electrician follows when laying cable and a commission relies on when accepting the network into operation. In Ukraine the number of stages and the scope of documentation are set by DBN A.2.2-3:2014 “Composition and content of design documentation for construction”, while the technical decisions follow the PUE (Electrical Installation Code) and the relevant standards, in particular DBN V.2.5-23:2025 “Design of electrical installations in residential buildings and public buildings and structures” — in force from 01.01.2026, replacing the 2010 edition. Below we go through the phases, the stages and the scope of the design — in plain language, but without the simplifications that later cost money.

What electrical network design is, and why bother if “the electrician knows anyway”

A power supply design is not “a piece of paper for approval”. It answers three groups of questions that would otherwise be settled by guesswork:

How much power, and of what kind, is needed. The electrical load calculation determines what supply the facility actually needs. Underestimate it and the breakers trip during peak loads; overestimate it and the client pays for years for excess connected capacity and more expensive equipment.

How it is to be implemented. Cable cross-sections, protective device settings, selectivity, reactive power compensation, earthing — all of this is calculated, not picked “from experience”. Here the PUE and the DBN are not bureaucracy but a distillation of other people's accidents.

Who is responsible for it. The design is signed off by a certified design engineer, and for facilities of medium and significant consequences the “Project” stage undergoes expert review. This is a legal construct that protects the client: if problems arise, there is a document, a calculation and a responsible person — rather than an installer's verbal advice.

Without a design it is impossible to legally connect a facility to the distribution system operator's grid, to commission it and — importantly for a business — to demonstrate to an insurance company or a fire inspector that the network was built to the standards.

Design stages under DBN A.2.2-3:2014

The number of stages depends on the facility's consequence class (CC1 — minor, CC2 — medium, CC3 — significant). For small and technically simple facilities the design is done in one stage; for complex ones, in two or three.

Stage	What it is	When it applies
EP — conceptual design	Fundamental decisions on siting, function and the facility's main parameters	Where required, for non-industrial facilities
TEO / TER — feasibility study / feasibility calculation	Justification of the case for construction, comparison of options, aggregated cost	Industrial facilities and engineering and transport infrastructure facilities; TER — in a reduced scope for simpler cases
P — the “Project” stage	Main technical decisions: power supply scheme, loads, equipment, estimated cost. Subject to expert review and approval	Facilities of consequence classes CC2 and CC3
R — detailed design documentation	Detailing down to installation level: drawings, cable schedules, specifications	After the P stage has been approved
RP — combined working design	P + R in a single stage: design decisions and working drawings in one package	Technically simple facilities, mostly class CC1

In practice, for most commercial facilities — a shop, a service station, a small production site — a single RP stage is enough. Two stages (P + R) appear where expert review is involved: large production sites, apartment buildings, high-hazard facilities. Mixing up the stages is also unwise for financial reasons: the P stage fixes the estimated cost, and that is exactly what the bank or investor sees.

What a power supply design includes

The typical scope of the power supply section (regardless of the number of stages — only the depth of elaboration changes):

Explanatory note: Input data, description of the facility, power supply reliability category (I, II or III under the PUE), the decisions taken and their justification.
Electrical load calculation: The foundation of the whole design: calculated load, demand factors — the basis for cable cross-sections, the transformer and the capacity requested from the operator.
Single-line diagram: The key document of the design: incomers, sections, protective devices, outgoing lines to consumers with ratings and cross-sections. Our plant builds the switchboard from the single-line diagram — if there is an error in it, that error turns into steel.
Selection of equipment and cables: Cross-sections by heating and voltage drop, verification against short-circuit currents, protection selectivity, selection of switchgear (GRShch main switchboards, ShchR distribution boards and, where required, a KTP or 10 kV switchgear).
Network layouts: Cable line routes, switchboard locations, lighting, socket outlets and power consumers on the building or site plans.
Earthing and lightning protection: Calculation of the earthing arrangement, the equipotential bonding system and, where required, external lightning protection.
Electricity metering: The metering unit in line with the requirements of the technical conditions and the Commercial Metering Code.
Cable schedules and specifications: The full list of cables and materials — what procurement buys from and what the installation crew works to.
Cost estimate documentation: The cost of construction — mandatory for the P and RP stages where the design brief provides for it.

Technical conditions (TU) for grid connection: where it all begins

If a facility is being connected to the public grid or is increasing its capacity, the first document is the technical conditions from the distribution system operator (DSO) — the regional oblenergo. The procedure is set by the Distribution System Code (NEURC resolution No. 310 of 14.03.2018).

The key things a client should know:

TU is not a separate service but part of the connection contract. Under the Code, the technical conditions are an integral annex to the connection contract and part of the design brief. In other words, the external power supply design is developed specifically to implement the TU, and the DSO checks that it complies with those conditions.

Connection can be standard or non-standard. Standard applies to small capacities close to existing networks (generally up to 50 kW and up to 300 m from the DSO grid), with a fixed connection charge rate. Non-standard covers everything else: there the cost and the scope of network construction are determined by calculation, and the quality of the design directly affects the amount.

The TU fixes the connection point, the capacity, the reliability category and the metering requirements. A competent designer helps determine the capacity correctly as early as the application stage — so that you do not pay for excess capacity and do not have to come back for new TU a year later.

Who prepares the design and how to choose a contractor

Design documentation is developed by organisations that employ certified design engineers — it is their qualification certificate and signature that give the design legal force. For the P stage, the expert review is carried out by an expert organisation; for facilities involving a grid connection, the external network design is agreed with the DSO.

What to look at when choosing, besides the certificates:

Experience with your type of facility. Designing an apartment, a production workshop and a solar power plant are three different worlds with different standards and different typical mistakes.

The link between design and delivery. A design detached from installation and procurement often turns out to be “paper only”: the specified equipment is out of production, the switchboard layout cannot physically be assembled. At LK Energy, design works alongside our own switchgear manufacturing (the plant in Odesa has been operating since 2015) and our electrical installation crews — so the single-line diagram is checked for buildability straight away, and the specification for the real availability of the equipment.

Support through to the result. A design counts as complete not when the album has been printed, but when the approvals have been obtained and the facility can be built and connected.

Frequently asked questions

How many design stages does my facility need?

It depends on the consequence class. For technically simple facilities (CC1) a single stage is enough — the combined working design (RP). For facilities of medium and significant consequences (CC2, CC3) two stages are carried out: the “Project” stage (P) with expert review, then the detailed design documentation (R). The number of stages is set out in the design brief.

Can electrical installation work be done without a design?

For facilities being connected to the DSO grid or commissioned — no: the technical conditions form part of the design brief, and without design documentation it is impossible either to have the external networks approved or to hand the facility over. Installation “without paperwork” means the owner bears full responsibility for the consequences.

How does a single-line diagram differ from a full design?

The single-line diagram is the heart of the design, but it is only one of its documents. A full design adds load and short-circuit current calculations, network layouts, earthing, cable schedules and specifications. A diagram without calculations is just a picture; the only way to check whether the ratings and cross-sections on it are correct is through the design.

Need a power supply design — from technical conditions to detailed documentation and a finished switchboard? See how our service is set up: power supply design at LK Energy. We will calculate the loads, develop the single-line diagram and support the design through to approval — and build the switchboard for it at our own plant.