Electrical installation, explained by a working electrician

Clear answers to the questions people actually ask: wire colours, RCDs and breakers, light switching, motors and contactors, testing. Every guide starts with a short answer, then shows the diagram, the reasoning and the common mistakes. Written for 230/400 V IEC installations, with notes on how the UK, the USA and other countries name and do things differently.

🎨 Wiring basics

Electrical wire colours: which conductor is which?

🛡️ Protection: RCDs, breakers, surges

PEN conductor and TN-C-S: where to split it into PE and N Surge protection device (SPD): Type 1, 2 or 3, and where to fit it? Type B or Type C circuit breaker: which one should you use? What does an RCD do, and which type do you need? Why does my circuit breaker keep tripping? Why does my RCD keep tripping?

💡 Light switching

Impulse relay: control a light from many places with push buttons Intermediate switch wiring: control a light from three or more places Two-gang switch wiring: two lights from one place Two-way light switching: how to control one light from two places

⚙️ Motors and contactors

Contactor wiring: start-stop latching and forward-reverse motor control Does swapping L and N reverse a single-phase motor? Star-delta starting: why and how it works

📏 Testing

Insulation resistance test: what it is and what reading is OK

Same thing, different name: UK, US and IEC terms

Electrical English is not one language. The same device has a different name in a British manual, an American video and an IEC standard. This table saves you a lot of confusion:

IEC / Europe	UK	USA / Canada
line conductor (L)	live	hot (ungrounded conductor)
neutral (N)	neutral	neutral (grounded conductor)
protective earth (PE)	earth, CPC	ground, equipment grounding conductor
RCD, 30 mA	RCD (RCBO with breaker)	GFCI, about 5 mA
miniature circuit breaker (MCB)	MCB	circuit breaker
distribution board	consumer unit	panel, load center
two-way switching	two-way switching	3-way switch
intermediate switch	intermediate switch	4-way switch
strappers	strappers	travelers
star-delta starting	star-delta	wye-delta
TN-C-S	PME	neutral bonded to ground at the service panel
230/400 V, 50 Hz	230/400 V, 50 Hz	120/240 V, 60 Hz (homes)

About the author

Łukasz Ćwierz (LukSee) is an electrician with more than 15 years on building sites in Poland, Germany and Norway, holding the Polish SEP qualification (E+D, group 1). He runs Bardzo Łatwo (“Very Easy”), a Polish channel about electrical work followed by over 260,000 people across social media. The videos are in Polish; this English section brings the most useful guides to everyone else.

Every guide is checked against the standards it mentions. If something is unclear or your country does it differently, use the 👍/👎 box under any guide: every comment is read.

Safety first: these guides explain how things work. Electrical work must be done with the circuit isolated and proven dead, by someone qualified, following the regulations of your country.