Manual Changeover Switch 1-0-2: What It Is and How to Choose
A changeover switch — also called a three-position switch or a 1-0-2 load transfer switch — is a manual device that moves the house supply from the grid to a generator and back. We explain what the three handle positions mean, how this isolator differs from an automatic ATS, and how to pick the rating and the pole configuration for your site...
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27 july 2026
ATS for a Generator and Inverter: Wiring Diagram and Installation
An ATS for a generator transfers the house load to the backup source in 50 ms and guarantees separation between sources. We go through the wiring diagram: where to run line, neutral and earth, where the transfer switch sits in the panel, how the hybrid-inverter scenario differs from the generator one, and why feeding a generator into a socket is lethal...
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20 july 2026
ATS (Automatic Transfer Switch): The Complete Guide
An ATS (automatic transfer switch) moves the load from the grid to a generator or an inverter by itself — in anything from 50 ms to 1-2 seconds. The UEC engineering department explains the operating principle, the four types of device, how to calculate the rated current from power, and how to choose the number of poles for your earthing arrangement...
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13 july 2026
ATS or Manual Transfer Switch: What to Choose for Your Home
There is always one device between the grid and your backup source — the transfer switch. We explain when you need an automatic ATS that switches in 50 ms, and when a manual 1-0-2 changeover switch is enough: a seven-criteria comparison and a scenario matrix for apartments, houses and businesses...
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06 july 2026
RCD Wiring Diagram in a Panel: Single-Phase and Three-Phase
Over 80% of panels in Ukraine are assembled with a single-phase layout, where the RCD is the only barrier between current leakage and electric shock. Three working wiring diagrams, conductor cross-sections and five typical installation mistakes that cause nuisance tripping...
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22 june 2026
RCD (Residual Current Device) — Full Guide: How to Choose, Connect, and Avoid Mistakes
A residual current device (RCD) is the only apparatus in a panel that detects current leakage to a person's body or an enclosure and instantly breaks the circuit. UEC engineering guide: operating principle, types, selection by current and sensitivity, wiring diagrams, installation mistakes...
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15 june 2026
RCD or RCBO — Which to Choose for an Apartment or House
RCD plus a breaker, or a single RCBO? We explain the difference, compare both across 8 key parameters and show when each solution is more cost-effective for an apartment, house or industrial site...
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08 june 2026
Voltage Relay Wiring Diagram for Electrical Panel: Single-Phase and Three-Phase
A voltage relay disconnects the circuit in 0.02 seconds during a voltage surge — but only if wired correctly. This article covers 5 field-tested wiring diagrams: basic single-phase, with contactor for loads over 40 A, socket-type, three-phase, and full protection with RCD. Plus 6 mistakes we see even from experienced electricians...
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25 may 2026
Voltage Relay + RCD and RCBO: Proper Connection Sequence in Electrical Panel
Voltage relay, RCD and RCBO are three protection devices with different functions. This article explains why they are not interchangeable, how to properly arrange them in the panel, and what mistakes to avoid during installation...
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18 may 2026
Voltage Relay - Complete Guide: How to Choose, Connect and Configure for Your Home
A voltage relay disconnects the electrical network within 0.02 seconds when voltage exceeds the safe 207–253V range per DSTU EN 50160:2023 and automatically restores power after stabilization. This guide covers the operating principle, 4 classification axes, 7 selection criteria, brand comparison with 2026 prices, panel wiring diagram and 6 common installation mistakes...
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11 may 2026
Voltage Relay vs Voltage Stabilizer - Which to Choose for Your Home
A voltage relay disconnects the network during dangerous voltage spikes, while a stabilizer corrects voltage to 220V. This article compares both devices across 8 parameters, examines three typical scenarios, and provides specific recommendations for apartments, private homes, and cottages with gas boilers...
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04 may 2026
Circuit Breaker Selectivity — Coordination & Selection Guide
Selectivity is more than just different ratings. This article explains how to properly pair circuit breakers so that only the damaged section is de-energized during a fault. Manufacturer tables, real examples, common mistakes...
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27 april 2026
Modular DIN-Rail Circuit Breakers — Selection Guide for Home
A complete guide to modular DIN-rail circuit breakers. We cover key characteristics — poles, rated current, trip curves B/C/D, and breaking capacity. Practical scenarios for apartments and private houses...
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20 april 2026
10 kA Circuit Breakers — Breaking Capacity & Selection Guide | UEC
10 kA breaking capacity is the maximum short-circuit current a breaker can safely interrupt. This article compares 4.5, 6, and 10 kA ratings, explains the difference between Icu and Ics, provides a selection algorithm, and lists common mistakes...
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13 april 2026
Breaking Capacity 4.5, 6, 10 kA - Comparison & Selection Guide
How to choose the breaking capacity (Icn) of a circuit breaker — 4.5, 6 or 10 kA? A UEC engineer explains the differences, provides a decision matrix for apartments, houses and commercial facilities, and breaks down IEC standards and common selection mistakes...
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06 april 2026
3P & 4P Circuit Breakers
Complete guide to three-pole (3P) and four-pole (4P) circuit breakers: catalog from UEC and GEWISS, current prices, specification comparison, wiring diagrams and expert advice on choosing protection for three-phase networks...
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23 march 2026
Where to Install a Double-Pole Breaker
A double-pole circuit breaker (2P) is most commonly installed at the main panel input — to completely disconnect both phase and neutral. Single-pole (1P) breakers are sufficient for branch circuits. This article covers PUE standards, 1P/1P+N/2P comparison, wiring diagrams, and common installation mistakes...
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16 march 2026
Circuit Breakers with Neutral Switching (2P, 1P+N)
We explain why installing a single-pole circuit breaker on the neutral wire is prohibited, when a double-pole breaker (2P or 1P+N) is required, and how to select the right protective device for your main panel, generator, and branch circuits. Practical advice from UEC engineers...
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09 march 2026
Consequences of Incorrect Circuit Breaker Selection: Hidden and Obvious Hazards
A wrong circuit breaker is not just an inconvenience — it is a real threat. An oversized rating melts insulation and leads to fire. An undersized one trips the lights and damages equipment. A wrong B/C/D characteristic causes nuisance tripping or delayed response during a short circuit. We break down all scenarios with tables, formulas, and a selection algorithm...
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23 february 2026
Nuisance Tripping of Circuit Breakers: Causes, Diagnosis, and How Wrong Trip Curves Exacerbate the Problem
Circuit breaker tripping without overload? This article covers 5 most common causes of false tripping (from loose terminals to inrush currents), step-by-step diagnostics, express-check tables, and expert advice from a UEC engineer with 15 years of experience. Learn how the wrong B/C/D trip curve amplifies the problem...
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16 february 2026
Understanding the differences between B, C, and D trip characteristic
Trip curves B, C, and D determine how sensitive a circuit breaker is to inrush currents. B (3–5 In) suits lighting and heating elements, C (5–10 In) is the universal standard for outlets, D (10–20 In) is for motors and heavy machinery. This article includes comparison tables, a real-world selection algorithm, and common mistakes...
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10 february 2026
380V Three-Phase Circuit Breaker: Calculation, Selection, and Installation
Complete guide to selecting a three-phase 380V circuit breaker: calculation formula with cos φ and √3, choosing between 3P and 4P, trip curves B/C/D for motors and heaters, cable capacity verification. Online calculator, cross-section tables and common mistakes checklist...
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06 february 2026
Автоматичні вимикачі для освітлення (6–10А) та розеток (16–25А): як вибрати і купити
Complete guide to choosing circuit breakers for apartments: 6–10A for lighting, 16–25A for outlets. We break down trip curves B and C, load calculations, coordination with RCDs and RCBOs. Practical advice from a UEC engineer...
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03 february 2026
220V Single-Phase Circuit Breakers: Prices, Calculation & Selection
How to choose a 220V circuit breaker for your apartment? Online calculator, cable cross-section selection table, B vs C trip curve comparison, UEC and GEWISS brand overview. Current 2025 prices in Ukraine...
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22 january 2026
