How to read an LED fixture spec sheet

A fixture spec sheet is a short document that answers about a dozen questions, and most of a specifying decision comes down to four or five of its rows. Here is what each one is doing, using the rows that appear on our own sheets.

Watts tell you the bill. Lumens tell you the light

Wattage is consumption. Lumens are output. They track each other loosely within a product family and not at all across families, so comparing two fixtures on wattage alone compares their electricity draw and nothing else.

Two rows from our own catalogue make the point:

• LED Batten Light, 4ft — 30W, ~3600lm
• Crater UFO High Bay — 100W, ~15500lm

The high bay is a little over three times the wattage and more than four times the output, because it is a different optical design doing a different job.

The `Replaces` row is a translation

Where a sheet carries a `Replaces` row, it maps the LED fixture to the legacy fixture it is intended to stand in for. The Crater UFO rows read ~300W HID at 100W, ~400W HID at 150W, ~600W HID at 200W and ~750W HID at 240W. In a retrofit that row is the fastest way to a fixture count: walk the building, note what is up there now, read across.

CCT is the number with a K

Correlated colour temperature describes the appearance of the light, not its quantity. Lower reads warmer, higher reads cooler and bluer.

You will see it written two ways on our sheets, and they mean the same thing:

• GoldBeach Backlit LED Panel — 3500K 4000K 5000K
• SunRiver canopy and adjustable wall pack — 30K/40K/50K

Where several values are listed for one part number, the fixture is selectable: the colour temperature is set at install rather than at order.

CRI describes colour accuracy

Colour rendering index compares how colours look under the fixture against a reference source, on a 100-point scale. The LED Batten Light lists CRI >80, which is the usual specification for commercial and industrial interiors. Where colour judgement is part of the work — retail display, inspection, paint — it is worth asking for the figure rather than assuming it.

IP and enclosure ratings describe where it can live

An IP rating is two digits: solids, then liquids. IP65, which appears across the Crater UFO, Astoria shoebox and SunRiver wall pack rows, means dust-tight and protected against water jets.

The EV chargers use a different scheme for the same purpose — a Type 4 electrical enclosure rating — because they are electrical equipment rather than luminaires. Either way the row is answering one question: can this be mounted where you intend to mount it.

Power factor and voltage are the electrician's rows

PF >0.9, on the Astoria and SunRiver sheets, describes how effectively the fixture converts supplied power into work. A poor power factor means drawing more current for the same output.

AC100-277V, which runs across the whole lighting catalogue, is a universal input range: the same part number works on a 120V circuit and a 277V circuit. On a mixed building that reduces the number of distinct fixtures you have to hold.

Dimming has to be planned, not added

Where a row reads 0-10V — the Crater UFO and the GoldBeach Backlit Panel both do — dimming runs over its own low-voltage control wiring. It is a decision made with the circuit design, not a setting discovered later.

Selectable wattage is one part number doing several jobs

Some sheets list several wattages against one part number. The GoldBeach Backlit Panel 6011BL reads 25/30/40W with 2950-4400lm, and the linear high bay reads 110/135/165W. Useful when the lighting layout is not final, or when you want one item on the shelf covering three light levels.

The IES file settles the argument

Most of the lighting collections publish IES photometric files, and where they exist they are listed by wattage and by input voltage — though not every wattage in a family has one. An IES file is the fixture's measured light distribution in a form lighting software can read, which is how a designer models a real room before anything is bought. Wherever they exist, they are linked from the product page under Documents.