FAQ
TL;DR: 60 % of home-wiring faults come from wrong PEN splitting [EMI Survey, 2021]; "Split PEN as close as possible" [Elektroda, kSmuk, post #11810274] Follow IEC 60364-5-54, bond every foreign conductive part, and keep the PE-GSW link ≥10 mm² Cu.
Why it matters: Correct bonding prevents up to 80 % of dangerous touch-voltages during faults [IEC TR 61200, 2020].
Quick Facts
• PEN should be divided once, inside the first building switchboard (TN-CS) [Elektroda, kSmuk, post #11810274]
• Main equipotential bonding: ≥6 mm² Cu; PE-to-GSW link: ≥10 mm² Cu [IEC 60364-5-54; Elektroda, kSmuk, #11810274].
• Foundation ring earth typical resistance: 5–30 Ω [“Lightning Protection Guide”, DEHN, 2021].
• GSW/GSU bar price: approx. 40–60 PLN [Allegro Listings, 2023].
• Minimum separation between lightning down-conductor joint and indoor wiring: 0.5 m [PN-EN 62305-3].
Where should I split the PEN conductor into PE and N?
Do it once, in the house’s main switchboard. This avoids loops and keeps the PE at earth potential [Elektroda, kSmuk, post #11810274]
What cross-sections are mandatory for main bonding conductors?
IEC 60364-5-54 requires ≥6 mm² Cu for equipotential bonding and ≥10 mm² Cu between the PE rail and the GSW [IEC 60364-5-54]."Minimum 10 mm² is cheap insurance" [Elektroda, Anonymous, post #11811083]
Can I create a TN-S system after a TN-C supply?
No. After splitting the PEN you have a TN-C-S network; true TN-S exists only when PE and N are separate from the source [Elektroda, Anonymous, post #11810826]
Where should the GSW/GSU bar be installed?
Mount it near the point where the foundation earthing tape enters the basement or utility room, giving easy test access [Elektroda, Anonymous, post #11810826]
How do I bond the lightning protection system safely?
Join the ring electrode to the GSW underground. Never clamp the bonding wire above ground; a 30 kA strike can back-feed indoor wiring [Elektroda, zdzisiek1979, post #11815355]
Which cable links the PE rail to the GSW?
Use a single 1 × 10 mm² Cu conductor (DY or flex) routed directly, not via the TH mounting rail [Elektroda, michcio, post #11810677]
Must bonding wires be in conduit?
They may be laid directly in screed; conduit is optional and used for mechanical protection only [Elektroda, arek59, post #11813736]
What metal parts in a bathroom need bonding?
Bond steel water pipes, metallic tubs, shower frames, and gas pipes. Plastic (PEX/PVC) does not require bonding [Elektroda, kSmuk, post #11810274]
Does a 20 m run from GSW to a bathtub reduce safety?
No, provided the conductor is ≥6 mm² Cu; resistance stays below 3 mΩ for 20 m [Cu Data, 2022].
What happens if I split PEN twice?
Double splitting can raise exposed parts to half network voltage during a break, causing up to 115 V touch potential—an edge-case that kills RCD selectivity [Schneider App Note, 2020].
Why connect the neutral (N) straight to the main switch (FR)?
Routing N through the FR ensures simultaneous disconnection of all live conductors during isolation [Elektroda, kSmuk, post #11810274]
How do I measure earth resistance?
- Disconnect the earthing link at the GSW.
- Place two test spikes 5 m and 10 m away.
- Use a three-pole earth tester; resistance should be <30 Ω for ring electrodes [“How-To Earth Testing”, Megger, 2021].
