One fixture, multiple jobs. That is the pitch. Here is the reality.
Selectable wattage and CCT fixtures let you adjust the power output and color temperature on site using a DIP switch before you close up the fixture. A single SKU can serve as an 80W warm-white fixture for a low-ceiling retail stockroom or a 200W daylight-white fixture for a 30 ft warehouse bay. The distributor stocks one box instead of nine. The contractor loads one product on the truck and sets it on the ladder. The specifier writes one line item that covers multiple scenarios. It is a genuine improvement in how commercial lighting gets specified, stocked, and installed. But it introduces new risks that fixed-output fixtures never had, and those risks show up in photometric layouts, DLC listings, and warranty claims.
What the DIP switch actually controls
Changes the power and lumen output
The DIP switch or rotary dial adjusts the driver's output current, which changes the wattage drawn by the LED array and the corresponding lumen output. Lower wattage = fewer lumens = less light. The relationship is approximately proportional: a fixture set to 50% of its maximum wattage produces roughly 50% of its maximum lumens. Typical options: 3-5 wattage steps (e.g., 80W / 110W / 150W / 200W).
Changes the color appearance
The DIP switch selects which LED array or phosphor configuration is active, shifting the color temperature. Common options: 3000K (warm white), 4000K (neutral white), 5000K (daylight white). Some fixtures offer 3500K and 4000K as the two lower options. CCT selection does not change wattage or lumen output in most designs, though some fixtures have slight lumen variation between CCT settings.
Both selections are made before or during installation, not after. Once the fixture is mounted, accessing the DIP switch typically requires opening the junction box or removing a cover plate. These are not dynamic, real-time adjustments like dimming. They are configuration settings chosen once and left alone.
The photometric layout problem nobody talks about
This is the most important section of this article. When a lighting designer creates a photometric layout, the simulation uses a specific IES file that corresponds to a specific wattage and lumen output. If the designer runs the layout at the 150W setting and the installer sets the fixture to 110W, the space will be under-lit by roughly 27%. The foot-candle values on the floor will not match the design.
The DIP switch setting must match the photometric design. This sounds obvious, but it is the single most common field error with selectable fixtures. The installer opens the box, sees the DIP switch, and either leaves it at the factory default (which may not be the designed setting) or changes it without consulting the layout. The fix is simple: the photometric layout should specify the exact wattage and CCT setting, and the installer should verify the DIP switch matches before mounting. Some contractors label the fixture's junction box with the specified setting so future maintenance does not accidentally change it.
For the lumen method calculation that determines how many fixtures you need at any given wattage setting, see the lumens guide. For warehouse-specific layout guidance, see the warehouse high bay guide.
DLC listing: not all settings are created equal
DLC listings are per product model AND per wattage/lumen configuration. A selectable fixture with three wattage settings may have all three listed on the DLC QPL, or only one or two of them. The listing shows the specific wattage, lumen output, and efficacy for each configuration that was tested and approved.
| Scenario | DLC status | Rebate eligibility |
|---|---|---|
| All wattage settings are individually listed on the DLC QPL. | Fully listed. | The project qualifies for rebates at any setting. Best case. |
| Only the highest wattage setting is DLC listed. | Partially listed. | The project only qualifies if the fixture is installed at the listed wattage. If set to a lower, unlisted wattage, no rebate. |
| The fixture model appears on the QPL, but the specific wattage you plan to use is not listed. | Not listed for that configuration. | No rebate at that setting. The fact that the same fixture is listed at a different wattage does not transfer. |
Always verify the specific wattage setting you plan to use on the DLC QPL (designlights.org/qpl) before specifying for a rebate project. For a full walkthrough of DLC verification, see the manufacturer evaluation guide. For rebate program details, see the rebate guide.
The inventory math: why distributors and contractors love this
Before selectable fixtures, a distributor stocking a single high bay product line needed separate SKUs for each wattage and CCT combination:
Fixed-output inventory example:
3 wattage options (80W, 150W, 200W) x 3 CCT options (3500K, 4000K, 5000K) = 9 SKUs per fixture type
Across 5 fixture types (high bay, troffer, wall pack, area light, strip) = 45 SKUs
At minimum stock depth of 10 units per SKU = 450 fixtures in inventory
Selectable fixture inventory:
1 selectable SKU per fixture type (covers all 9 wattage/CCT combinations) = 5 SKUs
At same stock depth of 10 units per SKU = 50 fixtures in inventory
Reduction: 90% fewer SKUs, 89% less inventory. Same coverage.
For the contractor, the benefit is equally concrete. Loading the truck for a multi-site job no longer requires pulling different SKUs for different locations. One box covers every scenario. If the site survey reveals a different ceiling height than expected, the installer adjusts the wattage on the ladder instead of driving back to the warehouse for a different fixture.
The tradeoffs you should know about
| Tradeoff | Detail |
|---|---|
| Higher unit cost | Selectable fixtures typically cost 10-20% more than fixed-output equivalents. The multi-driver or multi-array design adds component cost. The savings come from reduced inventory carrying cost, fewer return/exchange cycles, and job-site flexibility. |
| Slight efficacy penalty at some settings | The driver and LED array are optimized for the highest wattage setting. At lower settings, efficacy may be 5-10% lower than a purpose-built fixture at that wattage. For most commercial applications, this difference is negligible. For projects where maximum efficacy at a specific wattage is critical (DLC Premium thresholds, tight LPD budgets), verify the efficacy at the planned setting, not just the peak. |
| Configuration discipline required | Every fixture must be set to the correct wattage and CCT during installation. On a 200-fixture project, that is 200 opportunities to set the wrong switch. A written specification and a verification step in the commissioning checklist prevents this. |
| Spec sheet complexity | The spec sheet for a selectable fixture lists multiple lumen values, multiple wattages, and multiple efficacy numbers. Reading it correctly requires matching the row to the specific setting you plan to use. Comparing selectable fixtures from different manufacturers is harder than comparing fixed-output fixtures because the configurations may not align. |
When to use selectable vs. fixed-output
| Situation | Best choice | Why |
|---|---|---|
| Multi-site rollout (chain retail, franchise, property management) | Selectable | Different locations have different ceiling heights, ambient conditions, and customer preferences. One SKU covers all locations. Installers adjust on site. |
| Spec-bid project with a photometric layout locked before ordering | Either | The wattage is already determined by the design. Selectable adds flexibility if conditions change during installation, but fixed-output works fine if the design is final. |
| Distributor stocking for walk-in / will-call customers | Selectable | Covers the widest range of customer needs with the fewest SKUs. Reduces dead stock risk. |
| Project pursuing DLC Premium rebates at a specific wattage | Verify first | Confirm the specific wattage setting meets the DLC Premium efficacy threshold. If only the highest setting qualifies, and you plan to use a lower setting, fixed-output at the target wattage may qualify where the selectable does not. |
| Dark sky ordinance requiring 3000K max | Selectable CCT (with 3000K option) | Set to 3000K on site. If the ordinance is later relaxed or the fixture is moved to a non-restricted area, it can be reset to 4000K or 5000K without replacement. |
| Tenant build-out where the end-user has not confirmed CCT preference | Selectable CCT | Install the fixture, let the tenant see 3500K, 4000K, and 5000K in the space, and set the final preference. No RMA, no reorder, no second truck roll. |
Frequently asked questions
What is a selectable wattage LED fixture?
A fixture with a DIP switch or rotary dial that lets you choose between 2-5 wattage settings during installation. The driver adjusts its output current to match. Lower wattage = fewer lumens = less light. One SKU can serve as an 80W stockroom fixture or a 200W warehouse fixture depending on the setting. The selection is made once during installation, not dynamically like dimming.
Does changing the wattage setting affect the photometric layout?
Yes. Different wattage = different lumens = different foot-candles. The photometric layout must be based on the specific wattage setting that will be used. If the layout was designed for 150W and the installer sets 110W, the space will be roughly 27% under-lit. Always confirm the DIP switch matches the design. Label the fixture or junction box with the specified setting.
Are all wattage settings DLC listed?
Not always. DLC listings are per model and per wattage/lumen configuration. A fixture may be listed at its highest wattage but not at lower settings. Verify the exact wattage you plan to use on the DLC QPL before specifying for a rebate project. If the selected wattage is not on the QPL, no rebate at that setting.
How much inventory reduction do selectable fixtures provide?
A fixture with 3 wattage settings and 3 CCT options replaces up to 9 fixed-output SKUs. Across 5 fixture types, that is 45 SKUs down to 5. For a distributor, that means 90% fewer SKUs, dramatically less shelf space, and near-zero risk of having the wrong configuration in stock when the contractor shows up.
Is there an efficacy penalty at lower wattage settings?
Sometimes, but it is small. The driver and LED array are typically optimized for the highest wattage. At lower settings, efficacy may be 5-10% below a purpose-built fixture at that wattage. For most projects, this difference is negligible. If you are chasing DLC Premium thresholds or tight LPD budgets, verify the efficacy at the planned setting on the spec sheet and DLC listing, not just the peak efficacy number.
Can I change the setting after the fixture is installed?
Technically yes, but it requires accessing the DIP switch, which is usually inside the junction box or behind a cover plate. This means de-energizing the circuit and opening the fixture. It is not a dynamic adjustment like dimming. If you need real-time light level adjustment, you need a dimming protocol (0-10V or DALI) in addition to the wattage selection. See the dimming protocols guide for details.
