Most first enquiries stall because one number is missing. Here is the short list that lets a factory quote you properly on the first reply — and the two numbers people most often get wrong.
If you have ever sent a photo to a lighting factory and got back “what size do you need?” instead of a price, this is why. A custom fixture is engineered, not picked off a shelf, and the engineering needs numbers before the quotation can be real. Get these seven down and the first reply you receive will be a quotation rather than a question.
Not the floor-to-ceiling figure on the plan — the actual clear height where the fixture hangs, after the ceiling finish, after any beam or duct box. On a sloped or coffered ceiling this is different at every point, so measure where the fixture centreline will land.
Diameter for a round piece, length × width for a linear or rectangular one. If you are not sure, send the room dimensions instead and say so — a factory that builds these regularly can propose a size. What has to be exact is the clearance: the gap between the fixture and the surrounding walls, balustrades or furniture.
The drop is the distance from ceiling to the bottom of the fixture. Do not pick this in isolation: on a stairwell, the drop is set by the sightline from the floor below. On a dining table, it is usually dictated by how the light falls on the table surface rather than the ceiling.
Anything visual. A phone photo of a similar piece, a mood-board image, a hand sketch with dimensions. Your reference does not need to be a technical drawing; it needs to communicate the look you are after. Send two or three if the direction is between ideas.
Frame metal (steel, brass, aluminium), shade or decorative material (glass, crystal, acrylic, fabric, resin, marble), and the finish. If you have a RAL or Pantone code, send it. If you do not, describe it in words — “brushed brass, not polished” is genuinely useful.
One piece or twelve? Which country is it going to? When does it need to be on site? The destination drives voltage, plug and certification; the date drives whether what you are asking for is realistic. A factory that respects you will say “that date is not achievable” rather than accept the order and slip it.
This sounds like a detail and is not. If your own contractor is installing, the drawing needs to be readable by a general electrician. If nobody has been appointed yet, say so — a good factory will build in more modularity and supply a 1:1 rigging drawing.
You do not need a CAD file, a structural calculation or a final decision on finish. Those come after the first exchange, and on custom work the drawing stage is normally part of the process rather than something you have to arrive with. “I have a photo and a ceiling height” is a perfectly good starting point.
The normal sequence is: feasibility and an itemised quotation, then a scaled drawing for approval, then a prototype or representative sample, then production. If a supplier asks for full payment before you have approved a drawing, that is not a custom process — it is a gamble. Walk away.
A stairwell fixture only works if it is judged from the floor below, not from directly underneath. Here is how to set the diameter and the drop so it reads correctly from where people actually stand.
Read the guide ›The sample approval is the single point where you have the most leverage and the least time. A twelve-point check that prevents the expensive arguments later.
Read the guide ›Send dimensions, a drawing or a reference photo. You get a straight answer — including “this will not work” if that is the truth — within one working day.
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