Home Electrical Wire Size Chart: 1.5 / 2.5 / 4 / 6 / 10 mm² and Amp Rating per Size

Short answer: The right wire size depends on circuit load, not guesswork. 1.5 mm² for lighting circuits (16A breaker), 2.5 mm² for standard sockets (20A), 4 mm² for a small split AC (25–32A), 6 mm² for a larger AC unit or water heater (32–40A), and 10 mm² for feeding a sub-panel (50–63A). Full chart with amp ratings and prices below.

What's the wire size chart for home circuits, with amp rating per size?

Size (mm²)	Estimated max ampacity* (A)	Common use	Matching breaker
1.5	17.5	Lighting circuits	16A
2.5	24	Standard sockets/outlets	20A
4	32	Small split AC (up to 1.5 ton), kitchen outlets	25–32A
6	41	Larger split AC (2–3 ton), water heater	32–40A
10	57	Sub-panel feed, small central AC	50–63A

\* Figures are estimates based on general reference tables for copper, PVC-insulated cable (such as NYA), two or three loaded conductors in conduit, at 30°C ambient. They're a starting point for planning only, not a substitute for a licensed electrical engineer's calculation, which accounts for run length, how many wires are bundled together, and actual load current.

How do you pick the right size for a given circuit?

Calculate expected current first instead of guessing the size: current (A) = device wattage ÷ 220V for single-phase loads. A 1.5-ton split AC (roughly 1,400W) draws about 6.4A running, but inrush current at startup is much higher, so size the circuit on the nameplate's rated current, not a rough wattage estimate alone. Practical rule: don't load a circuit beyond 80% of the breaker's rating for continuous loads like AC units and water heaters — which is why fixed loads often get a size above the bare theoretical minimum.

What breaker matches each size, and why does it work only in that order?

The breaker protects the wire, not the appliance. That's why the breaker rating must never exceed the wire's max ampacity from the table above: a 20A breaker on 1.5 mm² wire (rated only 17.5A) lets current flow that heats the wire before the breaker trips — a common cause of scorched wiring behind old distribution boards. The reverse is safe: a breaker sized below the wire's rating (like a 16A breaker on 2.5 mm² wire) poses no risk, since it trips before the wire reaches its limit.

Why does Saudi summer heat change this chart?

The ampacity in the table above assumes 30°C ambient, while air temperature inside conduit exposed directly to the sun in Riyadh and Jeddah can exceed 45–50°C in summer. Every degree above 30°C lowers the wire's real safe ampacity, so the standard global table on its own isn't enough for any exterior run or sun-exposed conduit. Simplified field rule: go one size up from the chart for any circuit running through sun-exposed conduit or bundled with a large number of other wires. Exact correction factors and a worked example per size are coming as a separate article in this cluster.

What's the British NYA standard that most home wiring is sold under?

NYA denotes single-core copper wire (one conductor, one PVC insulation layer) built to the British standard at 450/750V, and it's the most common classification in Almadah's catalogue for indoor wiring. Most of it ships in 91.44-metre (300-foot) reels — a standard reel length inherited from imperial units still used across the cable industry — in sizes from 1 mm² up, with standard colour coding (brown for live, blue for neutral, yellow/green for earth). Bahra leads this line in Almadah's catalogue with the widest range of sizes and colours, followed by Riyadh Cables.

What do Bahra's NYA wires cost by size in Almadah's catalogue?

The table below sticks to a single product line for a fair size-by-size comparison: Bahra, British Standard NYA LS0H, 450/750V, 91.44-metre reel (VAT-inclusive, as of 29/09/2026):

Size (mm²)	Reel price (91.44 m)	Approx. price per metre
1.5	SAR 123.35	SAR 1.35
2.5	SAR 192.27	SAR 2.10
4	SAR 287.78	SAR 3.15
6	SAR 422.75	SAR 4.62
10	SAR 752.12	SAR 8.23

For context: the median price across the entire indoor wiring branch in Almadah's catalogue (all sizes and brands, including large industrial reels) is SAR 250.53 per reel as of 29/09/2026 — the most telling figure for an ordinary reel in this branch, away from the large industrial reels that pull the arithmetic mean up without representing home wiring.

Actual order history on this line is still limited relative to the catalogue's size, but among the few items with recorded orders, 1 mm² and 1.5 mm² NYA wire come up most often — consistent with lighting and standard socket circuits being the most common in any home wiring job.

Is it okay to use a smaller size to save money?

No. The price gap between two consecutive sizes is tiny next to the risk: upgrading a full reel from 1.5 to 2.5 mm² costs only about SAR 69 more, while undersizing a wire raises its temperature over time until the insulation fails or it ignites — one of the most common causes of home wiring fires. Size is always set by the circuit's actual load, never by a cost-saving budget.

Frequently asked questions

What wire size suits a lighting circuit?

1.5 mm² is the standard size for home lighting circuits, with a 16A breaker.

What wire size suits standard sockets/outlets?

2.5 mm² is the common size for standard socket circuits, with a 20A breaker.

What wire size suits a split AC unit?

4 mm² for small units up to 1.5 ton, and 6 mm² for larger units from 2 to 3 ton — the exact size depends on the rated current on the unit's nameplate.

Can you use a breaker rated higher than the wire's ampacity?

No. The breaker must never exceed the wire's max ampacity, or it loses its job of protecting the wire from overheating before it trips.

Why don't standard global ampacity tables hold up in Saudi summer?

Because they assume 30°C ambient, while temperatures inside sun-exposed conduit in Riyadh and Jeddah can exceed 45–50°C in summer, lowering the wire's real safe ampacity below the table figure.

What's the NYA standard that most home wiring is sold under?

NYA is single-core copper wire with one PVC insulation layer, built to the British standard at 450/750V, usually sold in 91.44-metre (300-foot) reels.

How much does a reel of electrical wire cost in Saudi Arabia?

From SAR 123.35 for a 1.5 mm² reel to SAR 752.12 for a 10 mm² reel from Bahra (British NYA standard), VAT-inclusive, as of 29/09/2026 — price rises gradually with size.

Is using an undersized wire safe to save money?

No; the price difference between sizes is tiny next to the risk of overheating and insulation failure, which can lead to fire.

Related

• Electrical wires and cables guide for Saudi Arabia: sizes, types, and heat derating — this cluster's hub article
• Indoor wiring category
• Power and control cables category