Slip Fitter vs. Trunnion vs. Arm Mount: Choosing the Correct Mount for Poles and Mounting Heights
Mounting hardware plays a critical role in outdoor and site lighting performance. Even when the correct fixture and lumen package are selected, improper mounting can compromise light distribution, structural integrity, and long-term reliability. Pole shape, mounting height, and application requirements all influence which mounting method is appropriate.
For area lights, flood lights, and site lighting systems, the most common mounting options are slip fitter mounts, trunnion mounts, and arm mounts. Each is designed for specific pole types, orientations, and installation conditions.
Overview of Common Outdoor Lighting Mount Types
Outdoor luminaires are typically designed with interchangeable mounting options to accommodate different site conditions. The three most widely used mounts differ in how the fixture interfaces with the pole or structure and how the light can be aimed.
- Slip fitter mounts attach directly over the top of a pole
- Trunnion mounts allow surface mounting with adjustable tilt
- Arm mounts extend the fixture away from the pole for improved spacing
| Mount Type | Typical Pole / Surface | Recommended Mounting Height | Primary Use Case | Design Limitation |
|---|---|---|---|---|
| Slip Fitter | Round or square poles (top-mounted) | 15–30 ft | General area and parking lot lighting with controlled forward throw | Limited aiming flexibility |
| Trunnion | Flat surfaces, walls, square poles with adapters | 10–25 ft | Directional flood and perimeter lighting | Not suited for uniform area distribution |
| Arm Mount | Round or square poles (side-entry) | 15–35 ft | Parking lots and roadways requiring extended forward coverage | Requires correct arm length and pole compatibility |
Selecting the correct mount is as important as selecting the correct wattage or optic.
Slip Fitter Mount: Applications and Limitations
A slip fitter mount slides over the top of a pole and is secured with set screws or internal clamps. It is one of the most common mounting methods for parking lots and roadway-adjacent areas.
Where Slip Fitters Perform Best
- Round or square poles with standard top diameters
- Mounting heights typically ranging from 15 to 30 feet
- Parking lots, roadways, and open site areas
Key Technical Characteristics
- Provides limited tilt adjustment, usually within ±10–15 degrees
- Relies on pole integrity for load-bearing support
- Maintains a clean, low-profile appearance
Slip fitter mounts are best suited for applications where forward throw and uniform area coverage are required without aggressive aiming angles.
Frequently Asked Questions
How do integrated LED fixtures improve lighting quality compared to tubes?
Integrated LED troffers are designed as a complete optical system (LED engine, driver, lens, and reflector). LED tube retrofits inherit the existing fluorescent housing optics, which may be discolored, non-reflective, or mechanically misaligned. Integrated fixtures can improve distribution and uniformity by controlling glare and increasing vertical illumination on walls and rack faces, reducing harsh contrast on work surfaces.
Is it true that integrated fixtures are harder to maintain than tubes?
In the short term, yes. A failed LED tube can be swapped quickly. With integrated fixtures, service typically involves replacing a driver or LED module, which may require an electrician and access to parts. In exchange, many integrated troffers and panels are rated for 50,000–100,000 hours depending on ambient temperature and driver design, reducing relamp frequency compared to tube-based maintenance cycles.
What are the hidden costs of keeping old troffer housings?
Reusing housings with LED tubes can reduce material cost, but the condition of the existing components becomes the risk. Aged lampholders (tombstones), wiring insulation, and grounding can degrade over time, increasing the chance of intermittent contact, overheating, or arcing. In tenant-facing spaces, legacy housings can also create visual non-uniformity (mismatched lenses, paint wear, inconsistent shielding), which often drives a full fixture replacement decision.
When should I choose LED flat panels over integrated troffers?
Flat panels are commonly selected for shallow plenums and tight ceiling conditions where deeper troffer bodies are difficult to fit. They provide a thin-profile form factor and can deliver uniform horizontal illuminance, but performance varies by design (edge-lit vs. back-lit). For glare-sensitive spaces, verify luminance control and optical shielding rather than assuming all panels behave like volumetric troffers.
Can I use existing dimming wires with both strategies?
Not always. Many integrated troffers and panels support 0–10V dimming by default, but LED tube retrofits vary widely. Some Type B tubes are non-dimmable, and ballast-compatible (Type A) dimming depends on the ballast and lamp combination. If dimming is required for controls compliance or operational needs, confirm the tube or fixture is explicitly rated for the control method being used.
Which strategy offers the best ROI for a 2026 retrofit?
It depends on space priority and labor. In public-facing areas where appearance, uniformity, and glare control matter, integrated fixtures often justify the premium through lower rework risk and fewer aesthetic complaints. In back-of-house or utility areas where speed and first-cost drive the decision, tube retrofits can deliver faster payback when operating hours are high and installation labor is minimal. Final ROI should be based on total installed cost, operating hours, maintenance access, and expected service life, not fixture price alone.
Brandon Waldrop
As the lead technical specialist for our commercial lighting technical operations, Brandon Waldrop brings over 20 years of industry experience in product specification, outside sales, and industrial lighting applications.
His career began in physical lighting showrooms, where he focused on hands-on product performance and technical support. He later transitioned into commercial outside sales, working directly with architects, electrical contractors, and facility managers to translate complex lighting requirements into energy-efficient, code-compliant solutions.
Today, Brandon applies that industry experience to architect high-performance digital catalogs and technical content systems, helping commercial partners streamline the specification process and deploy lighting solutions with total technical confidence.