Electrical take-off: sockets and light fittings

This guide follows French practice: French standards (NF DTU), French regulations and French bill conventions. Most sources are in French.

What you count, what you measure

An electrical take-off is first of all a count. Wiring accessories, lighting, safety and low-current equipment are counted per item, type by type; routes are measured per linear metre. The specification (CCTP) and the price breakdown (DPGF or schedule of rates) say what each line includes: a socket “point” may include its cable, its back box and its connection, or only the accessory.

Common items of the electrical package and their unit
Item	Measurement	Unit
16 A socket outlets, single or double	Count by model and by mounting height	u
Dedicated outlets (oven, washing machine, water heater…)	Count, with their circuit	u
Switches, two-way switches, push buttons	Count by function	u
Light points (ceiling points, wall lights)	Count by point supplied	u
Light fittings	Count by model	u
Self-contained emergency lighting units (BAES)	Count by type (escape, anti-panic)	u
Presence detectors, fire detectors	Count, depending on the package that supplies them	u
RJ45 data outlets, TV outlets, access control	Count by type	u
Distribution boards, enclosures	Count, with their equipment	u
Cable trays, trunking, conduit	Length, rises and drops included	ml
Cables and circuits	Length by cross-section, spare lengths according to the contract	ml

Read the legend before the drawing

No two design offices draw a socket the same way. Start with the legend: it sets the symbol of each item, the indices (“2” for a double socket, “h 1.10” for a mounting height, a letter for a circuit) and the light fitting references (“L1”, “L2”) that point to the schedule of light fittings in the specification. List the types before counting: one line per symbol and per variant.

A few traps come up again and again:

A double socket is counted as one “double socket” or as two sockets, according to the wording of the bill, never a bit of both.
A light point is not a light fitting: one point can supply two fittings, and the fittings may be supplied by another package.
Two-way switching controls one point from two places: two switches, a single point.
Grouped symbols (a socket outlet and an RJ45 outlet in the same box) are read zoomed in, not in the overall view.

On an architect's drawing that does not yet show the electrical layout, the take-off is done from the specification, room by room; write this down at the head of the take-off.

NF C 15-100: a minimum, not a take-off

In housing, the French wiring standard NF C 15-100 sets minimum equipment for each room; since the August 2024 edition, published in several parts, the part for dwellings is NF C 15-100-10. Manufacturers set out the minimums: Legrand, for example, states at least three socket outlets in a bedroom. The quantity surveyor counts what the drawing and the specification show. It is not their job to redo the design, but a drawing that shows less than the minimum deserves a question before the tender goes in. In offices, the specification and the layout of the workstations set the quantities.

Organise by room and by floor

An electrical bill is often read floor by floor, and the client's questions come room by room: “how many sockets in the meeting room?”. So count while keeping track of the room, or at least of the floor. This breakdown then serves every purpose: checking a room, pricing a variant, adjusting a variation when a partition layout changes. As in any take-off, separate from the start whatever will be priced separately: power and low-current systems (voice, data, security) are often different packages or subcontractors.

Cable trays, trunking and cables

The drawing shows the routes flat. The real length adds what cannot be seen on plan:

Rises and drops between the cable tray in the ceiling void and a board, a riser or an item. Their height is read on the sections, or worked out from the ceiling height and the mounting heights.
Spare lengths at cable ends, for the connection. Their length is a convention of the contract or of the contractor.
Cable tray accessories: lengths of fixed size (3 m in the vocational exam paper listed in the sources), couplers, supports, bends and tees. They follow from the run length and the changes of direction; electricians' exam papers ask precisely for the length to be taken off the drawing before deriving the quantity of each component.

A cable take-off remains an estimate until the circuit diagram is settled: one length per typical circuit, along the route, plus rises, drops and spare lengths. The contract says whether it must be itemised, or whether it is included in the price of the points.

Worked example

A single-floor office plate with a suspended ceiling at 3.00 m. The cable tray runs in the ceiling void along the corridor, then drops to just above the distribution board, whose top is at 1.80 m. The items are counted room by room.

Wiring accessories of the floor, counted by room
Room	16 A sockets	RJ45	Light points	Detectors	BAES
Open-plan office	24	16	12	4	2
Meeting room	6	4	4	1	1
Manager's office	5	3	2	1	0
Toilets	1	0	3	2	1
Corridor	2	0	5	2	3
Total	38	23	26	10	7

Cable tray of the floor
Line	Quantity
Horizontal run measured on plan	32.40 ml
Drop to the board: 3.00 − 1.80	1.20 ml
Cable tray	33.60 ml
3.00 m lengths: 33.60 / 3.00 = 11.2, rounded up	12 u

The cable of a socket at the far end of the open-plan office follows 28.00 m of cable tray, drops 1.20 m to the board and 2.70 m inside the partition to the socket, mounted at 0.30 m; with a spare length of 0.50 m at each end (taken for the example): 28.00 + 1.20 + 2.70 + 2 × 0.50 = 32.90 m. Measured on plan only, it would be 28.00 m: the true total exceeds it by 17.5%.

The total of each column is the sum of the rooms: if the client questions the meeting room, the answer is in its row.

The most common mistakes

Symbols counted without reading the legend, or two variants under one type.
Double sockets counted sometimes once, sometimes twice.
Light points and light fittings mixed up.
Runs measured on plan only, without rises, drops or spare lengths.
Items missed because they sit next to another symbol or are hidden under a dimension.
A count with no record by room: impossible to rework a room when the drawing changes.

Doing it in Kotelys

In Kotelys, each symbol of the legend becomes a type: a name (“Double 16 A socket”, “Escape BAES”), a marker shape, a colour and a total that stays up to date while you count.

The Count tool places one marker per click, with ten shapes to choose from and optional text: each item counted stays visible on the drawing, and a missed one shows.
Ctrl+F finds a word written in the PDF drawing, a light fitting reference or a room name, and highlights every place where it appears. A scanned drawing has no text to search (see taking off a scanned drawing).
Cable trays, trunking and cables are drawn with the Length tool, one type per width or per cross-section, with text repeated along the line if needed.
One zone per room or per floor, and the “Break down by zone” box in the reports splits each type; layers separate power from low-current systems.
The PDF quantity summary, the Excel workbook and the annotated drawing set all start from the same totals.

Kotelys does not recognise symbols: you click each item, and that is what makes the count checkable. Rises, drops and spare lengths are added in your estimate.

Kotelys open on the electrical drawing of an office floor: sockets, light points and detectors counted with coloured markers, cable tray drawn, totals by type in the Objects panel.

Further reading: electrical take-off in Kotelys, and the other guides.

Sources

Thresholds and values described as “taken for the example” are not rules: those of your contract (specification, bill of quantities) always prevail.

Electrical take-off: counting wiring accessories and measuring cable trays