I review lighting products before they are allowed into customer projects. Fixtures, drivers, emergency units, control gear—most years I review about 200 unique submittals, give or take. If you search “signify lighting news today 2025,” the top stories are about connected lighting, horticulture, and service contracts. The work I actually do is less glamorous: helping customers avoid expensive mistakes before the product is ordered.
After years of this, my position is simple: most lighting failures are spec failures, not product failures. I did not believe that when I started.
When I first moved into a quality role, I assumed the job was catching defects late in the process. Four years later, I spend most of my energy upstream. The expensive problems usually appear when someone trusts a handy rule of thumb instead of checking how the room, the plant, or the wiring will actually be used. I would rather spend ten minutes explaining the basics than deal with mismatched expectations later. An informed customer asks better questions, decides faster, and calls back less.
Names on the box do not tell you who stands behind it
People search “eaton sells cooper lighting to signify 2020” because they want the timeline. Eaton announced the sale of its Cooper Lighting business to Signify in October 2019, and the deal was completed in 2020 for approximately $1.4 billion. Signify itself was formerly Philips Lighting, and many products still use the Philips brand under license.
Why should a buyer care in early 2025? Because buildings live longer than brand labels. A Cooper-branded emergency luminaire installed in 2016 may now be supported by Signify. A specification that says “Philips” may actually be handled by Signify. The logo on the front does not tell you who carries the warranty, which drivers are in current inventory, or whether a control system is still supported. That is why I verify the manufacturer of record before I approve anything.
Downlight spacing: a number is not a plan
Search for “downlight spacing” and you will get a firm answer: four feet, five feet, six feet apart. That is a starting point, not a law. A downlight with a 60-degree beam on an eight-foot ceiling behaves differently from a 30-degree spot at ten feet. Spacing depends on beam angle, mounting height, and the plane you are lighting.
For an office, the work plane is usually about 2.5 feet above the floor. For a kitchen counter, it might be three feet. The distance between fixture and work plane is what drives the layout. That is why photometric reports include a spacing criterion, sometimes shown as S/MH. If the spacing criterion is 0.9 and the fixture is 5.5 feet above the work plane, the maximum center-to-center distance is around five feet. This is not a matter of taste; it is geometry.
For a typical eight-foot ceiling with a standard wide downlight, five-foot centers is a reasonable starting point for general lighting. For task areas such as kitchen prep zones, four-foot centers is more realistic. Then look at the wall. A wide beam aimed too close to a wall creates scalloped shadows, and a narrow beam aimed too far away leaves dark zones. The grid is planned on paper; the installation is permanent.
Grow light specs are about photons, not wattage
Wattage tells you what a fixture costs to run. It does not tell you how much useful light reaches the plant. If you compare grow lights by wattage alone, you are comparing the price of fuel, not the amount of food delivered.
Serious horticulture suppliers publish PPF in micromoles per second and a PPFD map over the canopy area. They also publish photon efficacy in micromoles per joule. The photometric test should be done under a recognized method such as IES LM-79-19, not calculated on a spreadsheet. A grow light without a PPF number is not a specification; it is a guess with a heatsink.
A practical example: 500 micromoles per square meter per second for 16 hours equals a DLI of 28.8 moles per square meter per day. Multiply the PPFD by photoperiod hours and by 0.0036. That DLI is what you compare with crop requirements. No sticker wattage can substitute for that calculation.
A three-wire switch is not a color-by-numbers puzzle
One question keeps appearing with contractors and building owners: “how to install a light switch with 3 wires?” The safest answer is not “connect black to black.” In older wiring, a white wire may be hot. In a three-way circuit, the common wire is not always black. Colors are a hint, not a contract.
When I review installation complaints, the same mistake shows up: someone identified wires by color, made an assumption, and found out later. The fix takes an extra six minutes with a voltage tester and a label. Shut off the circuit, identify the line and load, verify with a tester, and mark the common wire before removing anything. If you are installing a smart dimmer, check whether it needs a neutral and whether the driver is compatible with the dimmer. A dimmer that behaves perfectly with one LED driver may flicker with another. That is not bad luck; it is a specification issue.
Is this overkill for most projects?
Look, I am not telling every homeowner to commission a photometric study. A standard living room with standard fixtures will be fine with a sensible layout and a compatible dimmer. The trouble starts when a standard answer is applied to a non-standard situation: a high ceiling, a greenhouse bench, an older switch box, or an emergency lighting run.
Some people argue that buying a well-known brand and hiring a licensed electrician is enough. I half agree. A well-known brand reduces the chance of component defects, and a licensed electrician reduces the chance of unsafe installation. But neither fixes an application error. The electrician does not decide the spectrum or DLI for a tomato crop. The brand cannot tell you whether the PPFD map covers the far edge of the rack. Those decisions happen on paper, before the product is purchased.
Every informed customer I meet asks tougher questions. They ask for photometric files, they ask which test standard was used, and they ask for compatibility statements instead of believing a universal promise. That benefits both sides.
I have not yet met a buyer who regretted asking these questions before placing an order. I have visited projects where someone wished they had asked before the ceiling was closed. The difference was not the fixture quality. It was the paper underneath it.