What you may do yourself
Planning a panel is yours. Buying the parts is yours. Mounting devices on the rail and wiring them on a bench is, in most places, yours too.
Connecting that panel to the incoming supply is usually not. Across most of Europe the final connection and the certification are reserved to a licensed electrician, and in several countries the installation must be inspected and signed off before it may be energised. The rules differ by country and sometimes by region, so check yours before you plan the work — not after you have bought a box of breakers.
This guide takes you to the point where a competent panel, correctly specified and neatly assembled, is ready for that professional to check, connect and certify. That is a real saving in time and money, and it is where DIY honestly ends.
Step 1. Write down what you already have
Four facts decide almost everything downstream, and all four are readable in your existing panel or on your supply contract:
- The main breaker rating. The topmost breaker, marked something like C40 or B25. The number is the amperes.
- How many wires come in. Two or three means a single phase; four or five means three phases.
- The earthing system. Whether a separate protective conductor arrives, and what your supply is — see earthing systems.
- Your large appliances. Electric stove, water heater, washing machine, dishwasher, air conditioner, EV charger. Approximate wattage is enough.
If a number is not knowable without an electrician, do not guess it. Plan with what you know and mark the rest as a question for them.
Step 2. Split the home into circuits
A circuit is a group of points that share one breaker. Lighting and sockets never share one, so that a tripped socket does not leave you in the dark; each room's needs are counted separately; and heavy appliances get lines of their own.
The rules for how many points belong on one line are in splitting into circuits, and the list of appliances that always deserve a dedicated line is in dedicated circuits. The total, corrected by a demand factor and checked against your main breaker, is explained in load calculation.
This is the step the planner does for you: answer the questions and it produces the circuit list, the device choices and the layout, which you can then edit.
Step 3. Choose the protection
Every circuit needs protection against overload and short circuit — that is the breaker, and the letter on it matters as much as the number (trip curves). The breaker must match the cable, never the other way round (cable sizing).
Protection against electric shock is a separate job, done by a residual current device (what an RCD is). Wet rooms need 30 mA (why 30 mA), modern appliances with electronics need the right type (RCD types), and whether a circuit shares an RCD or gets its own combined device is the trade-off in RCD vs RCBO.
Two more depend on where you live: a surge protector if you are fed by an overhead line or live where storms are frequent (surge protection), and a voltage relay where the supply is unstable (voltage relays).
Step 4. Size the enclosure
Count the modules your devices occupy, then add room. A panel with no free space is a panel you will replace the next time anything changes — an EV charger, a garden line, a new circuit for the workshop. Twenty to thirty per cent free is the working rule (why leave reserve), and the choice of the box itself is in choosing the enclosure.
Step 5. Buy the parts
A panel is not only breakers. It is the enclosure, the DIN rails, the busbars and combs that distribute power along the row, the neutral and earth bars, the wire between devices, the labels, and the cable glands. Miss one and assembly stops halfway.
Reading the shopping list explains each line of the generated list and what to watch for when substituting brands — comb pitch and terminal size are where substitutions usually go wrong.
Step 6. Assemble in the right order
Assemble the panel with nothing connected to the supply, on a bench or with the incoming cable isolated and proven dead (working safely).
The order that works: mount the enclosure, fit the rails, place the incoming devices first and then each RCD section left to right, cut and fit the combs, land the outgoing cables, then wire the neutrals — every neutral returning to the busbar of its own RCD section, which is the single most common mistake (how a panel is wired inside). Label everything before you close it.
The planner's PDF gives you this as numbered steps generated from your own panel rather than generic advice (how to read your plan).
Step 7. Hand it over for testing and connection
The electrician checks what you built, connects it to the supply and certifies it: continuity, insulation resistance, loop impedance, RCD trip times. These need instruments and, in most countries, a licence.
Bring them the exported PDF. A plan with the circuit list, the device schedule and the single-line diagram turns the conversation from "what did you do here" into a review, which is faster and cheaper. What lies outside the tool's scope entirely — and always needs a professional — is listed in when to call an electrician.