Cable types by region

The same job — copper conductors with insulation and a protective sheath, suitable for embedded residential wiring — gets done by a different cable in every region. What goes where, what the markings mean, and why you can’t generally swap one for another.

Germany (and IEC-aligned EU): NYM-J

What it is. Multi-core PVC-insulated, PVC-sheathed copper cable. The most common residential cable in Germany, Austria, and aligned IEC countries.

Marking decoded. N = Normleitung (standard line) · Y = PVC insulation · M = sheathed (Mantelleitung) · J = with protective conductor (Schutzleiter, the green-yellow earth wire).

Common sizes (cross-section per conductor).

• 1.5 mm² — lighting circuits (10 A or 13 A B-curve breaker)
• 2.5 mm² — socket circuits, kitchen appliances (16 A B-curve)
• 4 mm² — electric showers, instantaneous water heaters (20 A)
• 6 mm² — cookers, EV chargers up to 32 A
• 10 mm² / 16 mm² — main-line tails, 3-phase EV chargers

For outdoor / underground runs, NYM-J’s sibling NYY (round PE-sheathed) replaces it.

UK: Twin & Earth (T&E, 6242Y)

What it is. Flat PVC-insulated, PVC-sheathed cable with two insulated conductors plus a bare copper earth conductor inside the sheath. Distinctive flat profile makes it easy to bury in plaster chases.

Reference. BS 6004 / 6242Y. The “6242Y” on the sheath is the BS designator.

Common sizes.

• 1.0 mm² — lighting circuits (6 A B-curve)
• 1.5 mm² — lighting and small radials (10 A B-curve)
• 2.5 mm² — ring final circuits (32 A RCBO), most socket circuits
• 4 mm² — shower circuits (typically 32-50 A depending on shower kW)
• 6 mm² — cookers, EV charge points
• 10 mm² — high-current showers, sub-main feeds

The bare-earth-inside-sheath layout is uniquely British; in nearly every other region the earth conductor is sleeved (green-yellow) inside the sheath. Electricians migrating across borders often comment on this.

US: NM-B (commonly “Romex”)

What it is. Non-metallic-sheathed cable with PVC-insulated conductors plus a bare copper grounding conductor. The 90 °C rating (NM-B) is the modern variant; older NM (60 °C) is essentially obsolete for new work.

“Romex” is a trademark (Southwire) for NM-B cable but is used colloquially for the cable type in general.

Common sizes (AWG — American Wire Gauge).

• #14 AWG — 15 A branch circuits (general lighting, general purpose outlets)
• #12 AWG — 20 A branch circuits (kitchen counter outlets, bathroom outlets per NEC 210.11)
• #10 AWG — 30 A circuits (electric dryers, some water heaters)
• #8 AWG — 40-50 A circuits (electric ranges, EV chargers)
• #6 AWG — high-current EV chargers, sub-panel feeds

AWG vs mm² quick reference. #14 AWG ≈ 2.08 mm²; #12 ≈ 3.31 mm²; #10 ≈ 5.26 mm²; #8 ≈ 8.37 mm²; #6 ≈ 13.3 mm². The numbers run inversely — smaller AWG number = larger conductor.

Where NM-B isn’t allowed. Outdoors, underground (use UF-B instead), in conduit in commercial settings, and across jurisdictions like Chicago that require EMT conduit for nearly all installations.

Canada: NMD90

What it is. Canada’s equivalent to NM-B, certified to CSA standards. Looks similar to NM-B but is not the same product — sheathing chemistry and certification chain differ. Required by the Canadian Electrical Code (CSA C22.1) for residential branch circuits.

WireSketch doesn’t have a separate Canadian region today; if you’re in Toronto or Vancouver, treat the app as a sketching tool only and have your licensed Canadian electrician spec the actual cable.

Australia / New Zealand: TPS

What it is. Thermoplastic Sheathed cable — flat, twin-and-earth profile similar to UK T&E but with sleeved earth (green/yellow) inside the sheath rather than bare.

Reference. AS/NZS 5000 series; sized in mm² (metric).

Common sizes.

• 1.0 mm² / 1.5 mm² — lighting circuits
• 2.5 mm² — general-purpose outlet circuits (20 A)
• 4 mm² — sub-circuits to fixed appliances
• 6 mm² / 10 mm² — oven, cooktop, EV charger, hot water

For tougher applications — rodent-prone areas, between brick courses, exposed runs — orange circular cable (SDI / V90-HT) replaces TPS.

Why they aren’t interchangeable

Beyond the obvious (AWG vs mm² sizing), the reasons cables aren’t swappable across regions:

• Voltage rating. European 230 V vs US 120 V cables have different insulation thickness for the same conductor size.
• Fire / smoke standards. EU residential cables increasingly require CPR Euroclass ratings (e.g. Cca for residential); US uses UL listing.
• Earth conductor type. Bare (UK) vs sleeved (most everywhere else) — affects termination and inspection.
• Insulation temperature rating. 70 °C (older PVC), 90 °C (NM-B, modern thermoset), 105 °C (specialty) — determines current-carrying capacity for the same size.
• Sheath chemistry. LSZH (Low Smoke Zero Halogen) cables required in some jurisdictions for places-of-assembly; standard PVC has higher smoke output in fire.

How WireSketch handles this

When you select a region in WireSketch, the cable recommendations engine outputs the right cable type with the right cross-section for each circuit:

• DIN 18015 / VDE 0100 → NYM-J in mm²
• BS 7671 → Twin & Earth (6242Y) in mm²
• NEC base → NM-B in AWG
• AS/NZS 3000 → TPS in mm²

The Renovation Brief PDF’s bill of materials shows the cable type and total length per circuit, so your electrician can quote and order accurately.