Copper vs aluminium cable in Pakistan — and what "alloy wire" really is

PILONE CABLES TECHNICAL TEAM

Copper inside the house, aluminium on the service drop and the long heavy feeder. Size for size aluminium carries about 78% of what copper carries — 16 mm² aluminium is 66 A against 85 A for 16 mm² copper — so a swap always means going one or two sizes up.

Aluminium is lighter and cheaper per metre but needs more cross-section, larger terminals and a termination made for it. Copper is smaller for the same current, easier to terminate on the small screw terminals inside a distribution board or an AC isolator, and is what every final circuit in a Pakistani house should be. "Alloy wire" at a Pakistani counter almost always means the aluminium range.

What a shopkeeper means by "alloy wire"

Ask for alloy wire in Pakistan and you will normally be shown aluminium conductor cable, sold as the cheaper alternative to copper for a service drop, a feeder or a submain. The word is loose. It can mean plain aluminium, it can mean an aluminium alloy conductor of the kind used on overhead lines, and it is sometimes used loosely of copper-clad aluminium — a thin copper skin over an aluminium core, which looks like copper at the cut end and behaves like aluminium in the circuit. The three are not the same product and only the first two are what a feeder is designed around.

So do not buy on the word. Ask three questions instead. What is the conductor material? What is the nominal cross-section in mm²? What is the maximum conductor resistance per kilometre? Resistance is the figure IEC 60228 actually defines, it is measurable on a delivered coil, and it settles the argument that a colour or a label cannot. Aluminium at 16 mm² is capped at 1.91 Ω/km; copper at the same size is 1.15. If a seller cannot give you the number, you are being sold a name.

Is alloy wire safe for house wiring? For final circuits — sockets, lights, an AC point — the answer in a Pakistani house is no, not because aluminium is unsafe in principle but because those circuits use small sizes and small terminals, and aluminium at those sizes needs more cross-section than the accessory was built for and a termination method that houses rarely get. Aluminium belongs where the sizes are large and the terminations are made for it: the drop from the pole, the feeder to a board, the run to a tube well.

Size for size, aluminium carries less

Aluminium conducts less well than copper, so the same cross-section carries less current. The ratio is close to constant across the range: 66 ÷ 85 = 0.78 at 16 mm², 87 ÷ 112 = 0.78 at 25 mm², 230 ÷ 299 = 0.77 at 120 mm². Whatever the size, expect roughly three-quarters of the copper figure.

PVC insulated, two and three loaded conductors. Current capacity per BS 7671 (IEC 60364-5-52), installation reference method C (clipped direct), 30°C ambient; conductor data per IEC 60228. Derate for conduit, grouping and higher ambient temperature. Verify sizing with a licensed electrician for your installation.
Size	Copper, 2 cores	Aluminium, 2 cores	Copper, 3 cores	Aluminium, 3 cores
10 mm²	63 A	48 A	57 A	43 A
16 mm²	85 A	66 A	76 A	59 A
25 mm²	112 A	87 A	96 A	76 A
35 mm²	138 A	107 A	119 A	94 A
50 mm²	168 A	130 A	144 A	113 A
70 mm²	213 A	165 A	184 A	144 A
95 mm²	258 A	199 A	223 A	175 A
120 mm²	299 A	230 A	259 A	202 A

Copper and aluminium of the same printed size are not interchangeable. Size by ampacity, never by the number on the jacket, and never substitute aluminium into a circuit designed for copper without re-sizing it. Have a licensed electrician confirm the size and the terminations for your load — or start with the cable size calculator.

The size you actually need when you swap

This is the table nobody publishes for Pakistan, and it is the one that decides whether the swap saves anything. Take the copper size the design calls for, read across, and take the first aluminium size that meets or beats its capacity. At the small end that is one size up; from 25 mm² upwards it is two.

Matching aluminium size is the smallest whose two-core capacity is not less than the copper it replaces. Capacities per BS 7671, reference method C, 30°C, PVC. Conductor mass computed at 8.89 kg/km per mm² for copper and 2.70 for aluminium. Cable outside diameter and gland and lug sizes grow with the conductor — check the terminal and the conduit will take it before ordering.
Copper	Carries	Matching aluminium	Carries	Step
10 mm²	63 A	16 mm²	66 A	1 size
16 mm²	85 A	25 mm²	87 A	1 size
25 mm²	112 A	50 mm²	130 A	2 sizes
35 mm²	138 A	70 mm²	165 A	2 sizes
50 mm²	168 A	95 mm²	199 A	2 sizes
70 mm²	213 A	120 mm²	230 A	2 sizes

35 mm² aluminium at 107 A looks close enough to 25 mm² copper at 112 A to tempt a one-size swap, and it is 5 A short. Being short before derating means being well short after it, so the table takes the next size instead. This is why "aluminium is one size up" is only half true: it is one size up to 16 mm² copper and two sizes up above it.

Why the service drop is aluminium and the house is copper

Weight is the reason, and it survives the sizing-up. Copper masses 8.89 kg per kilometre for each mm² of conductor; aluminium masses 2.70 — about 30% of the metal for the same cross-section. So even after stepping up to hold the same current, an aluminium conductor is still under half the weight: to carry 85 A you need either 16 mm² copper at 142.2 kg/km or 25 mm² aluminium at 67.5 kg/km, and 67.5 ÷ 142.2 = 0.47.

Conductor mass per kilometre of a single conductor, computed at 8.89 kg/km per mm² for copper and 2.70 for aluminium; insulation and sheath are extra and are the same either way. The last column compares the two conductors that carry the same current, not the two that share a number.
Size	Copper mass	Aluminium mass	Same-capacity comparison
10 mm²	88.9 kg/km	27.0 kg/km	63 A: 10mm² Cu 88.9 vs 16mm² Al 43.2 kg/km
16 mm²	142.2 kg/km	43.2 kg/km	85 A: 16mm² Cu 142.2 vs 25mm² Al 67.5 kg/km
25 mm²	222.3 kg/km	67.5 kg/km	112 A: 25mm² Cu 222.3 vs 50mm² Al 135.0 kg/km
50 mm²	444.5 kg/km	135.0 kg/km	168 A: 50mm² Cu 444.5 vs 95mm² Al 256.5 kg/km
95 mm²	844.6 kg/km	256.5 kg/km	258 A: no aluminium size in our range matches 95mm² Cu

A span from a pole to a meter board has to hold its own weight between two fixings, and a long feeder has to be carried, pulled and paid for by the kilogram of metal. Both arguments favour aluminium and neither applies inside a house, where the runs are short, the sizes are small, and the cost of the conductor is a minor part of the job. That is the honest reason the service drop is aluminium and the wiring behind the board is copper — not a claim about one metal being better than the other.

Where aluminium saves money, and where it does not

It saves on the run from the pole or the meter to the board, on a feeder down a plot to a tube well or an annexe, on a long submain between buildings, and on any run big enough that a copper equivalent would be 25 mm² or more.
It does not save on final circuits. Below 10 mm² the metal is a small share of the price and the sizing-up eats the saving; a 16 mm² aluminium cable in place of 10 mm² copper is a bigger, stiffer cable to pull through the same conduit.
It costs you at the joint. Aluminium needs terminals, lugs and glands rated for it, torqued properly, and a joint to copper made with a bimetallic connector rather than twisted together in a box. A cheap termination is where an aluminium feeder actually fails.
Count the whole job. Larger conductor means larger conduit, larger glands and larger lugs. On a short run those extras can cost more than the copper you saved; on a hundred-metre feeder they disappear into it.

The cable for each end of the job

Pilone draws both metals in Lahore. Copper runs through the standard cable range for fixed wiring and the flexible cable range where the tail has to bend; aluminium runs from 10 mm² to 120 mm² in the aluminium cable range. The two sizes most feeders land on are 10mm 2 core aluminium cable at 48 A and 16mm 2 core aluminium cable at 66 A; for a three-phase feeder take 16mm 4 core aluminium cable. On the copper side the equivalents are 10mm 2 core cable at 63 A and 16mm 2 core cable price at 85 A.

Frequently asked

Is alloy wire safe for house wiring?

Not for the final circuits. Alloy wire on a Pakistani counter means aluminium, and aluminium needs more cross-section and terminations made for it — neither of which the small sizes and small terminals of a socket or lighting circuit provide. Use copper behind the board. Aluminium belongs on the service drop, feeders and long submains, at 10 mm² and above.

What is the difference between alloy wire and copper wire?

The conductor metal, and therefore the size. Aluminium carries about 78% of copper's current at the same cross-section — 66 A against 85 A at 16 mm² — so it has to be one or two sizes larger for the same job. In exchange it weighs about 30% as much per mm² and costs less per metre. It also needs its own terminations.

Is aluminium cable OK for the WAPDA or K-Electric meter connection?

Aluminium is the normal conductor for the drop from the pole to the meter, which is why the incoming cable at most Pakistani meter boards is aluminium. What the utility will accept on its side of the meter is set by the utility, so confirm the size and material with the connection office before buying. The meter-tail rules are in the WAPDA meter cable guide and the K-Electric meter cable guide.

Copper is expensive — where can I use aluminium instead and save?

On the long, heavy runs: the service drop, a feeder to a tube well or annexe, a submain between buildings, and anything where the copper equivalent would be 25 mm² or larger. Below 10 mm² the saving is eaten by the sizing-up and the bigger conduit. Send us the load and the route length and we will price both metals against each other.

What size aluminium cable replaces 16mm copper?

25 mm². 16 mm² copper carries 85 A clipped direct at 30°C and 25 mm² aluminium carries 87 A, so it is the first aluminium size that clears it. 16 mm² aluminium at 66 A is well short. Check the gland, the lug and the conduit will take the larger diameter before you order.

Can I join aluminium cable to copper wiring?

Only with a connector made for the pair. Aluminium and copper twisted together in a junction box is the classic warm joint: the two metals form a cell in the presence of moisture, the contact resistance rises, and the joint heats. Use a bimetallic lug or connector, torque it to its specification, and keep the joint dry and accessible.

Why is aluminium cable so much lighter than copper?

Density. A conductor of 1 mm² cross-section masses 8.89 kg per kilometre in copper and 2.70 in aluminium. Even after sizing up to carry the same current, aluminium wins: 85 A needs 16 mm² copper at 142.2 kg/km or 25 mm² aluminium at 67.5 kg/km, which is 47% of the weight.

Copper or aluminium, priced side by side

We draw both in Lahore and sell at the day's rate — no dealer margin. Send the load, the route length and your city, and we will size both metals and quote them together: Punjab in 1–2 days, rest of Pakistan in 2–4.

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