Read up wise.
The reference work for electrical work: Ohm's law, voltage drop, cable sizing and protection — explained so it can be used in practice.
Articles
Become an electricianGet started · 5 minThe electrician makes light, heat and power work in everything from detached houses to industry and charging points. It's a trade with high demand, pay during training, and a straight path from curious beginner to skilled tradesperson. Here's why you should consider the trade.Ohm's law and power in practiceBasic electrical engineering · 9 minU = R · I and P = U · I are the foundation of all electrical calculation. Here is the relationship between voltage, current, resistance and power — with practical examples and an explanation of what cos φ does to the power in AC.Voltage drop — why and how muchCables & sizing · 9 minWhen current flows through a conductor, the voltage drops along the conductor. Too large a voltage drop gives dim light, poorly performing motors and unnecessary energy loss. Here are the formula, the conductivity for copper and aluminium, and the indicative limits.Cable cross-section — the three requirementsCables & sizing · 15 minA conductor cross-section must simultaneously handle current-carrying capacity, voltage drop and short-circuit — the largest of the three requirements determines the cross-section. Here are the three requirements, and why the current-carrying capacity figures must always be looked up in the standard.Protection against electric shockProtection & safety · 12 minHow RCDs (HPFI/RCD), automatic disconnection and equipotential bonding together protect against electric shock. The protection rests on basic protection and fault protection — and the normative limits are always looked up in DS/HD 60364-4-41.Overcurrent protectionProtection & safety · 10 minThe difference between overload and short circuit, and how the tripping characteristic (B/C/D) of circuit breakers is chosen. Overcurrent covers two phenomena, both of which must be interrupted before the conductor is damaged.Power factor and three-phase powerBasic electrical engineering · 10 minActive, reactive and apparent power, the power triangle, and why cos φ matters in practice. A low power factor draws more current than the active power alone would require — and that costs you in cables and equipment.Standards and legislation for electriciansRules & standards · 10 minWhat laws and standards govern electrician work in Denmark, and what is the hierarchy? Here is the overview of the Electrical Safety Act, the Installation Regulation and the DS/HD 60364 series — with the most important changes in 2024 and 2026.Verification of electrical installationsQuality & documentation · 12 minVerification is not optional — it is a legal requirement that must be carried out by the authorised company before the installation is energised. Here are the sequence, the measurements and the documentation requirements to DS/HD 60364-6.RCD types and charging stations for electric vehiclesProtection & safety · 12 minThe choice of RCD type for a charging station is set out in law in DS/HD 60364-7-722 and depends on whether the charging box has approved DC residual current blocking. Type AC is prohibited — and it is not a matter of indifference whether you choose type A or type B.Grounding and grounding systemsProtection & safety · 12 minThe earthing system (TN, TT or IT) determines how the supply's neutral point and the installation's PE conductor are connected to earth — and it affects requirements for disconnection time, impedance and choice of protective equipment.KLS and authorization as electrical installerRules & standards · 7 minThe Authorisation System and KLS Requirement (Quality Management System) are the Cornerstones of the Danish Electrical Installation Regime. Here are the Requirements, Documents and Consequences of Non-Compliance — with Precise References to BEK 722 and 725 from 2024.Common Regulations 2026Rules & standards · 6 minFrom 1 January 2026, the Common Regulations 2026 apply, bringing together the grid companies' requirements for connection to the grid: notification before work starts, power factor, phase imbalance, short-circuit level at the connection point and drawing of the metering section. Here are the most important requirements and what they mean for installations.Electrician training — new executive order from August 2026Education · 6 minFrom 1 August 2026 the electrician programme has a new executive order (BEK no. 460/2026), and competence goals, certificates and basic subjects are now set out in the training regulations. The two specialisations, the journeyman's exam in two parts and the requirement of 02 before the main programme already existed. Here is an overview of the programme and the requirements.The history of the electrician trade in DenmarkThe craft's history · 7 minThe electrician trade emerged with electrification around 1900 and was gradually tied together by three things: a set of safety rules (the strong-current regulations), a licensing scheme and formal vocational training. Here is the long view — from the first installations through European harmonization to today's green transition.Safety with electrical workProtection & safety · 12 minElectricity is invisible and can kill. Before you touch an installation, it must be made safe according to the five safety rules — and if it cannot, the strict L-AUS rules apply. Here is the life-critical basic discipline: the five rules, the voltage test, personal protective equipment, arc flash and first aid.Solar cell system (PV) — installation and DC safetyRenewable energy · 13 minSolar cells are one of the fastest growing task types — and the DC side behaves completely differently from the AC current the electrician knows. Here are the system's structure, string voltage and its temperature dependency, DC breakers, potential equalisation of modules and the correct RCD choice according to DS/HD 60364-7-712.Overvoltage and lightning protection (SPD)Protection & safety · 11 minTransient overvoltages from lightning and switchings destroy sensitive electronics in microseconds. Surge protection devices (SPD) have become a normative requirement in many installations. Here are the SPD types, placement, the critical 0.5 m rule and the interplay with lightning protection.Motor installation, motor protection and frequency convertersAutomation & motor control · 15 minMotor control is core craftsmanship in industrial and automation installations. Here are the four start methods (DOL, star-delta, soft start, frequency converter), the correct setting of motor protection, the frequency converter's EMC cabling and leakage currents, the correct RCD choice — and machinery safety according to DS/EN 60204-1.Building automation and intelligent installations (KNX)Automation & motor control · 11 minKNX is the open standard for intelligent building installations, where lighting, heating, solar shading and blinds are controlled via one bus cable instead of individual wires. Here is the difference between conventional and bus installation, KNX topology, the bus cable and ETS programming.Panel construction and panel documentation (DS/EN 61439)Quality & documentation · 14 minBuilding, labelling and documenting a switchboard is daily craftsmanship — and it is governed by DS/EN 61439. Here is the switchboard standard, the difference between original and switchboard manufacturers, the three verification methods, the enclosure ratings IP/IK, temperature rise, the busbar's short-circuit capacity and the requirements for labelling and circuit diagrams.Lighting technology and light controlLight & lighting · 13 minLight is a core area in the electrician's trade. Here are the photometric quantities (lumen, lux, candela, luminance), colour temperature and colour rendering, glare (UGR), lighting requirements after DS/EN 12464-1, emergency lighting after DS/EN 1838 and modern light control with DALI — plus the lumen method worked through.Data, tele and network installationData & communication · 13 minStructured cabling is core craft in modern installations. Here is twisted pair cabling Cat 5e/6/6A, 100 m channel, shielding, fibre, patch panels and connectors, PoE to IEEE 802.3, coax/antenna and equipotential bonding and separation from 230 V.Electrical diagrams, symbols and reference designationsQuality & documentation · 11 minReading and drawing electrical diagrams is part of the basic course. Here are the diagram types (circuit diagram, main circuit/control circuit, single-line versus multi-line), the graphical symbols according to DS/EN 60617 and the reference designation system (=installation / +location / −component) according to IEC/EN 81346 — with a motor starter diagram read step by step.Control technology and PLCAutomation & motor control · 12 minControl and automation engineering is a specialisation. Here is hardwired relay logic (AND/OR, self-holding, interlocking), PLC structure and cycle, programming languages according to IEC 61131-3 (ladder, FBD, ST) and sensors and actuators — the link between diagram and real machine.Systematic troubleshooting of installations and control systemsQuality & documentation · 11 minFault-finding is a daily core competence and a separate assessment criterion. Here is the method: symptom analysis, the halving method, systematic narrowing along the signal path, the four classic fault types and how to locate breaks, short circuits, earth faults and poor connections with a multimeter and megger — safely, per DS/EN 50110-1.Fire-technical installations (ABA, ABDL and alarm)Protection & safety · 12 minAutomatic fire alarm systems (ABA), fire door closing (ABDL), and signalling systems are a real installation task for certified electricians. Here are the detector types, central equipment, the difference between conventional and addressable supervised circuits, ABDL magnets, and the interface with other installations — according to DBI guidelines and the DS/EN 54 series.The electric car needs charging — from granny charging to a wallboxProtection & safety · 8 minMany electric cars are charged from an ordinary socket-outlet. The Danish Business Authority (formerly the Danish Safety Technology Authority) advises against it for daily use. Here are the rules for mode 2 charging, the dedicated charging socket-outlet, the wallbox, registration with the grid company and the tenant's new right to a charging point from 1 January 2026.Balcony solar panels with a plug — why they are illegal in DenmarkRenewable energy · 4 minA plug-in solar PV system for the balcony can be bought in many shops. In Denmark it must not be connected with a plug in an ordinary socket-outlet. Here are the three risks that the Danish Business Authority (formerly the Danish Safety Technology Authority) points to, and the legal way to connect the system.The heat pump and the electrical installationRenewable energy · 7 minHeat pumps are a growing task for the electrician. Here are the rules for the permanent connection, the safety switch, the protected zone of propane heat pumps, leakage current and RCD, registration and own circuit — and why the F-gas ban from 1 January 2027 makes R290 common.The electrical installation report when a house is soldRules & standards · 6 minWhen a house is to be sold, an authorised electrician often makes an electrical installation report. Here are the rules from the executive order and the Danish Business Authority's handbook version 20 (sik.dk): who may make the report, the four possible answers, which rules the installation is assessed against, and reports for common property.The construction site and the ground — temporary installations and underground cablesInstallation · 7 minA construction site installation is always a new installation, even if it only stands for half a year. Here are the rules for responsibility, ACS boards, RCD and inspection — and the Installation Executive Order's measures for cables in the ground: depth, protection, colour and marker tape.The Danish special requirements — 12 rules from the Installation Executive OrderRules & standards · 5 minThe Installation Executive Order (BEK 1082/2016) has a number of Danish special requirements that must always be complied with: RCD limits, fuse and socket-outlet, number of circuits and socket-outlets in the dwelling, the height of the board and resetting after tripping. Here are the 12 most important gathered in one table.ID cards on large construction sitesWork environment · 4 minThe Danish Parliament has passed an act on ID cards on construction sites with a construction sum over DKK 100 million. Here are which sites are covered, what the card must show, who is responsible for it, and the rules on checking in and out. The date of entry into force has not yet been set.