Duct Bend (Hockey Stick): The Service Duct Sweep That Brings a Supply Out of the Ground

The groundworker backfills the trench, the slab goes down, and the drive gets laid. Then the network engineer turns up to pull the new electricity cable into the meter box and finds a tight right-angle elbow buried at the wall. The cable will not go round it. The only fix now is to break out the surface, dig down to the bend, and swap it for the gentle sweep that should have been there from the start. A service duct bend, the hockey stick, costs almost nothing to get right and a fortune to get wrong.

What it is and where it sits

A service duct is the buried plastic pipe that protects an incoming utility supply on its way from the street to the building. The cable does not lie loose in the soil. It runs inside a duct, so that the supplier can pull it through, replace it later if it fails, and so that anyone digging in the future hits a marked pipe rather than a live conductor. The duct goes in empty during groundwork, with a draw cord threaded through it, and the cable is pulled in afterwards.

The hockey stick is the bend on the end of that duct. The straight run of duct comes along the trench from the street, at the depth the supplier requires, and then it has to turn upward to surface at the meter box, the cabinet, or wherever the supply terminates. That turn is made with a long, gentle, sweeping bend rather than a sharp elbow. Side on, the buried run plus the upward curve looks exactly like a hockey stick lying in the ground with its blade against the wall, which is where the name comes from.

For a moved or new electricity supply, the hockey stick brings the duct up out of the trench and into the back of the meter box on the wall. The cable is then drawn from the street, along the buried duct, round the sweep, and up into the box, where the distribution network operator (the company that owns the cables and the meter position, abbreviated DNO) makes off the connection.

Why the radius has to be gentle

Every cable has a minimum bending radius. That is the tightest curve the cable can be bent to without harming it, and it is normally quoted by the manufacturer as a multiple of the cable's overall diameter, for example eight or twelve times the diameter for an armoured supply cable. Bend it tighter than that and the conductors inside can be stretched or crushed, the insulation can crack, and on a steel wire armoured supply the armour can deform. A cable that has been forced round too tight a curve may fail straight away, or it may fail quietly months later once it is energised and buried under a finished surface.

There is a second, more immediate problem. A supply cable is stiff and heavy. The network engineer pulls it through the duct with a rope attached to the draw cord, often over a run of many metres. If the bend at the end is a sharp elbow, the cable simply jams in the corner. The pulling force needed to drag it round a tight turn climbs fast, and the engineer is not going to risk damaging their own cable or the duct by hauling on it. They will down tools and tell you the duct is not fit to pull.

A long-radius sweep solves both at once. The curve stays inside the cable's minimum bending radius, so the cable is not damaged, and the gentle path lets it slide round under reasonable pulling force. This is why a service duct bend looks so different from a drainage bend. Drainage bends are tight because water does not care about bending radius; a cable does.

Duct sizes and colour coding

Buried services in the UK are colour coded so that anyone excavating can tell at a glance what they have found before they damage it. The colours follow long-standing utility convention:

• Electric: black, usually with a red stripe or red printed marking, to ENA and DNO specification
• Water: blue
• Gas: yellow
• Telecoms and data: grey or black with marker tape

For a domestic electricity supply, the duct and its hockey-stick bend are black with red marking. Twinwall electric duct (a pipe with a corrugated outer wall and a smooth bore inside, the outer corrugation giving crush strength and the smooth bore letting the cable slide) is the common modern choice. It comes in standard sizes quoted as the inner over the outer diameter, the usual domestic options being 50/63mm and 94/110mm. A single-phase house supply normally runs in the smaller duct; a larger supply, a three-phase connection, or a long run may need the 94/110mm.

The size you fit is not your free choice. It must match the DNO's specification for the supply being installed. The DNO publishes the duct type, diameter, colour, and the bend radius they will accept, and if you fit something different they can refuse to pull the cable. Get the specification from the supplier's connection paperwork before you buy anything, and buy the duct, the couplers, and the hockey-stick bend as one matched system from the same range so the joints actually fit together.

The prices in the table above are 2026 retail figures from drainage and civils merchants who sell to the public. The bend itself is the cheapest part of the whole job, which is exactly why it is daft to fit the wrong one. A correct long-radius sweep costs little more than a sharp drainage elbow, and getting it right the first time avoids the surface ever coming back up.

How it is laid

The duct goes in during groundwork, while the trench is open and before the supply cable arrives. The sequence is straightforward but every step matters, because once it is backfilled and the surface is reinstated, the only way to fix a mistake is to dig it all back out.

The bend has to end up in the right place against the wall, at the right height and angle to feed the back of the meter box cleanly. Aim the sweep so the duct rises vertically into the box rather than fighting its way in at a slant. Where the duct passes through the wall, the hole is sealed around the duct afterwards so that water, gas, or vermin cannot track in along the opening; a proper duct seal or sealing compound does this, not just a smear of mortar.

Bringing the duct through the wall and into the meter box

The meter box on the wall has a knockout or entry at the back or base for the incoming duct. The hockey stick is positioned so its top end lines up with that entry, and the duct passes through the wall and into the box. Inside the box, the cable is drawn up out of the duct and presented for the DNO to terminate at the cut-out and meter.

The duct entry into the box has to be sealed once everything is in. An open duct mouth is a path for draughts, damp, and even gas if there is ever a leak in a nearby service, so the gap between the cable and the duct, and the gap between the duct and the wall, are both sealed. This is part of getting the connection signed off, not an optional extra.

Who lays it and who connects it

The duct and its bend are laid by the groundworker as part of the trenching and external works, but always to the DNO's specification rather than to whatever happens to be on the van. The homeowner or builder is usually responsible for providing the trench and the duct to spec; the DNO provides and pulls the cable and makes the connection. This split catches people out, because the two jobs are done by different parties at different times, sometimes weeks apart.

The practical consequence is that the groundworker has to get the duct, the bend, the depth, the colour, and the draw cord exactly right while the supplier is nowhere near the site, and then the supplier turns up later expecting to pull a cable through a duct that meets their rules. If it does not, the supplier walks away and the groundwork has to be reopened. The way to avoid that is to get the DNO's duct specification in writing before the trench is dug, and to have the groundworker lay the duct to that document, not to a generic standard.

Common mistakes

A tight 90-degree elbow instead of a sweep. The single most common and most expensive error. A short-radius drainage-style elbow either stops the supply cable jamming halfway or breaches its minimum bending radius and damages it. The fix once it is buried is to break out the surface and replace the bend. Always fit a long-radius sweep bend specified for cable.

Wrong duct size or colour. Fitting the wrong diameter, or a blue water duct or yellow gas duct on an electricity supply, means the duct does not match the DNO's specification and the connection can be refused. The cable may also not pull through an undersized bore. Match the supplier's spec exactly: black with red marking, at the size they state.

No draw cord left through the bend. Without a pull rope threaded through before backfill, the network engineer has nothing to attach the cable to. Pulling a cord through a buried, bent duct after the fact is awkward at best and sometimes impossible, so the cord goes in before the trench is closed.

Too little cover or no warning tape. A duct laid too shallow, or with no coloured warning tape above it, leaves the supply at risk from the next person who digs and gives them no warning before they hit it. Lay it to the required depth with the tape above, the same as any buried service.

Not laying it to the DNO's specification. A duct that is technically a "duct" but does not match the supplier's published spec for type, size, colour, depth, or bend radius can be rejected on the day the engineer arrives to pull the cable. Getting the spec first and laying to it is the only way to be sure the connection goes ahead.

Where you'll need this

• Utility meter relocation - the hockey-stick bend brings the moved electricity supply duct up out of the trench and into the meter box, kept to a gentle radius so the cable can be drawn through

A service duct bend turns up on any project where an underground supply has to rise out of the ground and into a building or a meter position, whether that is a moved electricity meter, a new connection to an extension or outbuilding, or a relocated supply on any extension or renovation. It is laid as part of groundwork to the supplier's specification, and it works alongside the buried duct run, the draw cord, the warning tape, and the meter box it feeds.