Armoured or unarmoured cable? What the steel is actually for

PILONE CABLES TECHNICAL TEAM

Armoured for anything buried, run outdoors, or exposed where a spade, a vehicle or a rodent can reach it. Unarmoured for the protected indoor run in conduit, trunking or a chased wall.

The steel-wire layer is mechanical protection, not extra electrical capacity: an armoured cable of a given size carries no more current than an unarmoured one of the same size, and a buried run is on a different installation method again, so its rating has to be worked out for the ground it sits in. Choose the armour for the route; choose the size for the load.

What the armour adds, and what it does not

An armoured cable is an ordinary cable with a layer of steel wires laid over the bedding and a second sheath over that. The steel takes the crushing, the impact and the pull that would otherwise reach the conductor: a pickaxe at a depth nobody recorded, a truck across a yard, a rat in a duct, a cable dragged over a sharp edge during the pull itself. That is the whole job of the armour, and it is worth paying for exactly where those risks are real.

Three things the armour does not do. It does not raise the current rating — capacity is set by the conductor size and the installation method, and burying a cable changes that method for the worse, not the better. It does not make the cable weatherproof on its own; the outer sheath does that, and a damaged sheath lets water to the steel. And it does not automatically become your earth: some designs do use the armour as the protective conductor, but that is a decision for the person designing the circuit, who has to confirm the armour's own resistance is low enough for the fault current. Do not assume it, and do not leave a run without an earth on the assumption that the steel counts. The steel and the second sheath cost money per metre, and they cost again at the gland and the pull — which is why armour is bought for the route, not fitted everywhere as insurance.

Where each belongs

Route decides the construction; load and length decide the size. Burial depth, ducting and route marking are set by the installation design — have a licensed electrician confirm both for your job.
Run	Cable	Why
Buried feed to a house, annexe, gate or tube well	Armoured	Soil pressure and digging damage; nobody remembers where the trench went
Along an outside wall, a boundary or a roof edge	Armoured	Impact, rodents and anything leaning a ladder against it
Factory floor, yard, cable tray at low level	Armoured	Trolleys, forklifts and machinery move; the cable does not
Chased into a wall, in conduit or trunking	Standard	The conduit is already the mechanical protection
Panel wiring, machine tails, appliance connections	Flexible	Needs to bend, not to resist a spade
Submersible pump drop into a bore	Submersible pump cable	A different problem again: permanent immersion, not impact

The pattern is simple enough to state once: armour and conduit do the same job — they keep the world off the cable. You pay for one or the other, and only where the world can reach. What that means for a trench — depth, ducting, warning tape and how the run is recorded — is covered in the underground cable guide.

The sizes we armour, and what they carry

Pilone draws armoured cable from 4 mm² to 95 mm². The conductor inside is the same copper as the unarmoured range, so the size ladder reads the same — but the figures below are clipped-direct figures. A buried cable sits on a different installation reference method, and its rating depends on the soil, the depth, the ducting and whether other circuits share the trench. Use this table to pick a starting size, then have the buried rating confirmed.

Copper conductors, two loaded cores. Current capacity and voltage drop per BS 7671, installation reference method C (clipped direct), 30°C ambient; conductor resistance and strand construction per IEC 60228. Buried and ducted runs use a different reference method and must be rated separately. Verify sizing with a licensed electrician for your installation.
Size	Class 2 strands	Capacity, 2 cores	Capacity, 3 cores	Voltage drop
4 mm²	7/0.85	36 A	32 A	11 mV/A/m
6 mm²	7/1.04	46 A	41 A	7.3 mV/A/m
10 mm²	7/1.35	63 A	57 A	4.4 mV/A/m
16 mm²	7/1.70	85 A	76 A	2.8 mV/A/m
25 mm²	7/2.14	112 A	96 A	1.75 mV/A/m
35 mm²	19/1.53	138 A	119 A	1.25 mV/A/m
50 mm²	19/1.78	168 A	144 A	0.93 mV/A/m
70 mm²	19/2.14	213 A	184 A	0.63 mV/A/m
95 mm²	37/1.78	258 A	223 A	0.46 mV/A/m

Buried runs are usually long ones, so voltage drop decides the size more often than current does. A 60 A load 60 metres down a plot on 16 mm² loses 2.8 × 60 × 60 ÷ 1000 = 10.1 V, which is 4.6% of 220 V and over budget; on 25 mm² it is 1.75 × 60 × 60 ÷ 1000 = 6.3 V, or 2.9%. Check your own length in the voltage drop calculator.

Burial depth, ducting, route marking, gland selection and the earthing arrangement are all safety-relevant and are set by the installation design, not by the cable. Have a licensed electrician confirm the cable, the size and the earthing for your run — or start with the cable size calculator.

Armoured cable, factory-direct

ARMOURED CABLE · 4MM² – 95MM²

Armoured Cable, All Sizes

Drawn on the Pilone line in Lahore, 4 mm² to 95 mm², copper conductor to IEC 60228. Tell us the route — buried, outdoor or industrial — the load and the metres, and we quote the size and today's rate. Common picks: 16mm armoured cable for a house feed, 25mm armoured cable for a long one.

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Frequently asked

Do I need armoured cable for an underground run to an outhouse or a tube well?

Yes, that is the case armour exists for. A buried cable has to survive soil pressure and, years later, somebody digging where no record says a cable runs. Armour is also the reason such a run stays serviceable when a boundary wall is built over it. Size it on the load and the length together, because a run down a plot is long enough for voltage drop to decide the size.

Can I use ordinary cable underground if I put it in a pipe?

A duct helps with pulling and future replacement, but it is not the same protection: pipes crack, joints fill with water, and a spade goes through PVC as easily as through a sheath. Where the design does call for unarmoured cable in a duct, that is a decision the installation designer makes and records — not a substitution made on site to save on the coil.

Does armoured cable carry more current than unarmoured?

No. Capacity comes from the conductor size and how the cable is installed. 16 mm² copper is 85 A clipped direct at 30°C whether it is armoured or not, and burying it changes the installation method so the buried figure has to be worked out separately. Armour buys mechanical protection, nothing electrical.

Does the armour count as the earth?

Sometimes, by design — never by assumption. Using the steel as the protective conductor requires the designer to confirm its resistance is low enough to clear a fault through the protective device, and requires glands that bond it properly at both ends. If that has not been checked and recorded, run a separate earth conductor. See earth cable.

What size armoured cable from the meter to the house?

It depends on the sanctioned load and the distance, not on the plot size. Most single-phase house feeds land on 16 mm² or 25 mm² copper — 85 A and 112 A clipped direct — with the larger size chosen when the run is long. The meter-side rules are set out in the WAPDA meter cable guide and the K-Electric meter cable guide.

Not sure if your run needs armour?

Send the route on WhatsApp — buried, outdoor or indoor — with the load and the metres, and we will tell you which construction and which size, at the factory rate. Punjab in 1–2 days, rest of Pakistan in 2–4.

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