There's no fixed number of feet that works for every commercial walkway. A defensible spacing is the candidate center-to-center distance that passes a photometric model built from the exact luminaire's output, mounting height, walkway geometry, and the project's illuminance and uniformity criteria.
Skip the generic spacing rule and start with those inputs. Once a candidate layout passes the model, confirm it in the field after installation before calling the design final.
Key Takeaways
- Spacing is a modeled output, not a fixed rule; it depends on the exact luminaire's photometry, mounting height, walkway geometry, and the project's illuminance and uniformity criteria.
- Collect walkway geometry, lighting criteria, and exact luminaire configuration before testing any candidate spacing.
- Model candidate locations, check minimum and average illuminance plus uniformity, then compare the calculation with field measurements after installation.
- Dark patches, glare, and complex geometry each call for a different fix, not one blanket spacing change.
- Bring in a qualified lighting professional when criteria are unclear, the model keeps failing, or measured results don't match the design.
What determines commercial bollard light spacing?
A workable spacing number always traces back to a calculation, not a rule of thumb. The IES Illuminance Selector lists the horizontal and vertical illuminance criteria and uniformity ratios that projects use to set a walkway's lighting target, available in both lux and US customary foot-candles.
Once that target is set, the calculation runs the exact luminaire's photometric file against a grid laid over the walkway. It checks whether a given center-to-center distance keeps ground light above the minimum everywhere and within the uniformity ratio the project needs. Change the mounting height, the configured output, the optic, or the walkway width, and the model has to run again. The result worth keeping is a documented candidate layout: a spacing distance, the exact configuration it assumes, and confirmation that it met the project's criteria before anything gets installed. If you're sizing outside lights for house entry walks instead of a commercial site, the same modeling logic applies at a smaller scale, though a home project rarely needs a full photometric file to get usable results.
Inputs to collect before modeling
Before testing any candidate distance, you need three categories of information: the physical walkway, the lighting criteria the project must meet, and the exact fixture you plan to model. Skipping any one of these makes the resulting spacing number unreliable.
Walkway and site geometry
Record the walkway's width, centerline, and edges, along with every curve, transition, entrance, and fixed obstruction such as a tree well, sign, or utility box. Treat any stretch that breaks the straight-path pattern, like an intersection or elevation change, as its own zone instead of assuming one repeated spacing carries through it.
Project lighting criteria
Get the maintained illuminance and uniformity criteria that actually apply to this project, in the US customary foot-candle units the design will use. Don't substitute a number pulled from a general online source; the criterion has to match the project's own requirements or specifying authority.
Exact luminaire configuration
Gather the mounting height, configured wattage, distribution type, cutoff or shielding option, aiming, and the manufacturer's photometric file for the specific fixture, not just its product family. As a bounded example, the documented listing for one 36-inch bollard configuration shows 480 lumens with selectable 12W, 15W, and 24W settings, optional Type III or Type V distribution, and optional louver, glare-shield, or diffuse-lens optics. Those listed facts describe the inputs a model needs; they don't by themselves prove a particular spacing or project fit. Before you commit any figures to a layout, our LED spec sheet guide walks through how to pull the right electrical and optical data off a spec sheet for exactly this kind of comparison.
How to model candidate bollard spacing
Modeling candidate spacing is a repeatable sequence, whether it's done by hand or in photometric software. Each step feeds the next, and any failed check sends you back to an earlier one.
- Define the calculation grid. Lay a grid of points across the walkway's width and length, including edges, transitions, and any zone you separated out earlier.
- Load the exact photometric data. Use the manufacturer's photometric file or equivalent data for the specific configured luminaire, not a generic series average.
- Place candidate bollard locations. Test a specific center-to-center distance, mounting height, and orientation against the grid.
- Calculate the point results. Run or obtain the modeled illuminance value at each grid point for that candidate layout.
- Review minimum, average, and uniformity. Compare the modeled results against the project's criteria, and check the calculation methods described in ANSI/IES LS-6-20(R25), which covers photometric data use, standardized calculation procedures, and assessment of computed results.
- Inspect for low points and glare. Look at where the source is visible from typical viewing angles along the path, then record whether the candidate passes or fails and why.
- Compare with field measurements after installation. Once the layout is built, measure actual illuminance and note any gap between the calculated and measured result.
A candidate that fails any of these checks needs a design change before it goes to purchase, not a note to "monitor it after installation."
How to revise spacing when the layout fails
The type of failure tells you which input to change next, not how many feet to add or subtract. A dark patch, excess brightness, and visible glare each point to a different fix.
| Observed condition | Design response to test | Next verification |
|---|---|---|
| Dark patches or low points between fixtures | Test a tighter candidate spacing, then review distribution, output, or mounting height if it's still short | Re-run the grid calculation for minimum illuminance |
| Uneven brightness or heavy overlap | Review distribution type and mounting height rather than assuming more fixtures fixes it | Check the uniformity ratio against the project criterion |
| Visible source or reported glare | Review shielding, cutoff, optic choice, and aiming; use fixture shielding to reduce glare | Re-model the exact shielded configuration and check sightlines |
| Curves, intersections, or entrances | Model the transition as its own zone instead of extending the straight-path spacing through it | Confirm the zone passes its own grid check |
More output is not an automatic fix for glare, and tighter spacing is not an automatic fix for uneven coverage; each response above targets the specific condition observed, and the model has to confirm the change actually worked.
Pre-purchase and pre-installation verification
Getting a candidate layout to pass the model is only half the job. The purchased product and the installed site both have to match what the model assumed, or the layout stops being reliable.
Before purchase
Match the quote against the exact SKU, configured wattage, optic or distribution option, mounting height, and photometric file used in the model. Selecting a fixture on lumens alone skips the distribution and cutoff data the calculation actually depended on.
Before installation approval
Confirm the model still reflects the real walkway: the same obstructions, mounting surface, and fixture orientation. If the site changed since the model was built, the layout needs to be reassessed before it gets signed off. Local code, permitting, and electrical decisions stay with the responsible authority and qualified professionals, not with this calculation.
After installation
Compare the installed result with the calculation. Note any low points, glare, aiming issues, or obstructions that weren't in the model, and document them. Our commercial lighting pilot scorecard offers a structured way to record visibility, comfort, and uniformity feedback during that field check. If the measured result doesn't match the design, revise the layout rather than accepting the gap.
Code, electrical, and professional design boundaries
This workflow covers how to model and verify spacing; it doesn't cover local code, accessibility, permitting, or electrical design, which stay with the applicable authority or a qualified professional. Do not approve or install a layout that fails the project's illuminance or uniformity criteria, or that creates unacceptable glare; revise the design or get qualified review first.
Electrical questions, including circuit design, breaker sizing, and wire sizing, belong with a licensed electrician; this guide doesn't provide those steps. Complex geometry, unclear project criteria, a model that keeps failing, or a field measurement that doesn't match the calculation are all reasons to bring in a lighting professional rather than keep adjusting numbers on your own. If your project needs full photometric planning or a documented layout for approval, our lighting design service page outlines that kind of project-specific support.
FAQs
How far apart should commercial bollard lights be?
There's no defensible universal distance. Model candidate center-to-center distances for the exact luminaire configuration, mounting height, and walkway geometry against the project's illuminance and uniformity criteria, then keep the candidate that passes.
How do you keep foot-candle levels consistent along a walkway?
Consistency is judged from the modeled minimum and average illuminance and the uniformity ratio, not from how bright the path looks by eye. Check the calculation grid for low points between fixtures, and confirm those same points measure acceptably after installation.
Does a glare shield automatically allow wider bollard spacing?
No. A glare shield or cutoff changes the fixture's optical configuration, which can change the modeled result, but it doesn't automatically justify a wider distance. Re-run the model with the exact shielded configuration and check source visibility from typical viewing angles before widening anything.
When should a lighting professional verify the bollard layout?
Bring in a lighting professional when project criteria are unclear, the site has complex or retrofit geometry, the calculated layout keeps failing, or the field measurement doesn't match the approved design. Code, accessibility, and electrical decisions should always go through the responsible qualified professional.
