The most common question before ordering: how many metres of cable? The answer is a sum with three numbers – ceiling height, desired height of the lamp holder, allowance – plus a few rules of thumb on where the lamp holder should hang.
The formula
Visible cable = ceiling height − height of the lamp holder's lower edge above the floor − ceiling rose height (2 to 4 cm). Add 15 cm for the connection in the ceiling rose. Example: ceiling 250 cm, lamp holder should hang 150 cm above the floor, ceiling rose 3 cm → 97 cm visible + 15 cm = 112 cm to order, rounded up to 1.2 m. In the configurator you enter the visible length; we add the allowance.
Where the lamp holder should hang
Above the dining table: bottom of the bulb 60 to 70 cm above the tabletop, so with a 75 cm table height that's 135 to 145 cm above the floor. Lower and it glares at whoever's sitting opposite, higher and the lamp loses its connection to the table. With shades open at the bottom, go for 70 cm; with visible low-lumen bulbs, 60 cm is fine.
Over a kitchen island or counter: 75 to 85 cm above the work surface (working height 90 cm → 165 to 175 cm above the floor), so you don't bump your head while working and can see across the island.
Free in the room (hallway, living room corner, next to the armchair): bottom edge at least 200 cm above the floor if people walk underneath; next to the armchair it can go down to 140 to 160 cm, because nobody walks there.
Bedside pendant: bulb 20 to 30 cm above the bedside table, i.e. about 80 to 100 cm above the floor – the lamp deliberately hangs low.
Spider and ceiling hook
For lights with ceiling hooks, add the arc: distance from ceiling rose to hook × 1.5, plus the vertical drop. The drop is calculated as above, but from the hook, not the ceiling rose. If the hook and ceiling rose are at the same ceiling height (the norm), the calculation is: arc + (ceiling height − lamp holder height). The formula in detail is in the spider instructions.
Plug-In Lights
Here the route to the socket comes into play: from the ceiling hook to the wall, down the wall, to the socket – measure each stretch straight and add 10 per cent for curves around corners. For a 3 m route, 3.3 m is realistic, plus the drop, plus 30 cm spare, because otherwise the plug ends up dangling in mid-air.
Better too long
Shortening takes a minute; extending only works with a junction box. We supply cable sold by the metre in 10 cm steps; 15 cm extra is the minimum, 30 cm is comfortable. Surplus cable can't be stowed in the ceiling rose – if you're unsure, order 20 cm more and cut to length when connecting.