Electrical Cable Size Guide

Cross-section, ampacity, and why length matters

Cable size in mm² (1.5, 2.5, 4, 6, 10…) sets how much continuous current copper can carry without overheating under standard installation methods. Larger cross-section lowers resistance and voltage drop. Long runs to rooftop ACs, motor sheds, or backyard shops in Lahore can show dim lights and hot terminations even when ampacity tables looked “fine” for a short stub — voltage drop checks matter.

Pair every circuit with an MCB at or below the cable’s safe capacity. A 2.5 mm² lighting/socket radial protected by a wildly oversized breaker is unsafe. Conversely, forcing a high continuous AC load through undersized cable causes nuisance heat long before a correctly small breaker trips.

Insulation type (PVC insulated cable common in building wiring) must suit temperature and environment. Outdoor, underground, or DC solar runs may need different constructions — ask rather than assuming house wire belongs on a hot roof array.

Practical starting sizes used on Lahore boards

These are common planning anchors — confirm with your electrician and local practice tables:

• Lighting circuits: often 1.5 mm² copper with 6A or 10A MCBs when design and length allow. • General socket circuits: commonly 2.5 mm² with 16A or 20A protection depending on layout and diversity. • Dedicated AC / geyser / heavy appliance radials: frequently 4 mm² or 6 mm² with matched 20A–32A (or as designed) breakers — never “whatever was leftover on the reel.” • Sub-mains and larger feeders: size from calculated load, diversity, and voltage drop; may step to larger mm² with 40A/63A class protection when the design says so.

Iron lead / extension leads are for temporary portable use, not as a substitute for fixed building wiring. Permanent PVC insulated cable runs belong in conduit or approved concealment as per the electrician’s method.

Always reconcile earth continuity and, for socket/wet groups, residual protection strategy (RCCB/RCBO) alongside copper size — cables alone do not provide shock protection.

Buying cable and matching breakers at GlobalPlus

When you WhatsApp GlobalPlus, list mm², cores (e.g. 2-core / 3-core), approximate metres or coils, and whether the job is residential rewiring, shop board, or feeder. Mention MCB ratings you plan to fit so the team can flag obvious mismatches. Ask for PVC insulated cable availability alongside MCB range cartons for board packages.

Copper market movement means rates are quoted on inquiry — no fake fixed website prices. Dealers should state city and carton/coil volume for wholesale. Visits for sample feel or pickup are appointment-only in Lahore.

Link this guide mentally with the MCB rating guide: decide load → cable → breaker, not breaker first. For solar DC runs, ask specifically for DC-capable cable and DC MCB families rather than house PVC on the array side.