Watermelon Light Mounting & Wiring Guide

“Watermelon” describes a style of light, not one installation standard. These four United Pacific examples show why the lamp size, mounting hole, attachment method and wire functions belong in the buying decision.

Four installations to compare

Measure the mounting point

Check the specified cutout or hole, attachment hardware and available depth behind the panel. The 39231’s lamp size and installation hole are different measurements. The 34847 and 39231 share a stated hole size but use different retention methods. A full-size flush-mount light needs its own mounting information; do not transfer either mini light’s hole size to it.

Read the wire functions for that part number

The examples use different ground paths and wire assignments. Do not carry a wire-colour assumption from one light to another. Match the manufacturer’s diagram and operating voltage to the exact part being installed. Follow its instructions for connections, protection and mounting.

Compare the featured lights

• 4 LED Dual Function Mini Watermelon Light – Amber US$12.19
• 4 LED Watermelon Double Fury Light – Amber & Blue w/Clear Lens US$14.69
• UltraBurst Glass Watermelon Light Flush Mount Kit – Amber LED/Lens US$43.59
• Dual Function Glass Watermelon Flush Mount Kit – Dark Amber US$34.29

Glass Is Class Gen 2 installation checks

Start by choosing the exact assembly or component. A Glass Is Class Gen 2 watermelon light, a replacement AlphaFit bulb and a housing-only listing are separate purchases unless the product page says they are included together.

Single-colour AlphaFit Gen 2 bulbs provide 15W dim and 20W high in the same colour. Dual-colour Glass Is Class AlphaFit bulbs use one power setting. Follow the wiring instructions for the selected version and confirm the housing, lens, connector and mounting parts before ordering.

For a complete custom pickup installation, compare the Glass Is Class Gen 2 pickup-truck watermelon light kit. The kit includes one Gen 2 light, one Diode Dynamics DD4104 switched harness and one Alpha Series A0007 stainless bracket. It is a custom-installation package, not an OEM year/make/model fitment claim.

For other mounting positions, browse watermelon and penny-light brackets, then match the opening, hardware, orientation and clearance to the exact light and mounting location.

Choose a bracket for the mounting location

Start with the light and the place it will mount. Check the cutout, fasteners, rear clearance and wire route together. A bracket described as universal still needs to match the selected lamp and mounting surface.

• Frame rail: compare the Alpha A0008 straight-down clamp bracket, supplied with mounting hardware, with the A0007 right-angle bracket or A0016 flat bracket for a different mounting arrangement. A0008 does not include the light.
• Penny-light frame mounting: the Alpha A0034 clamp-on bracket has a 3/4-inch cutout and is supplied without a light. Compare the lamp’s retention method, bezel clearance and the space needed for the clamp; matching the hole size alone is not enough.
• Inside an air cleaner: A0029 brackets for Peterbilt 389 and Kenworth W900 require premium 15-inch Donaldson air cleaners with a push-down-and-twist locking lid: the lid comes off by itself, while the mesh/intake assembly stays in place. They do not fit 13-inch air cleaners or the style with four external nuts where the whole top and mesh assembly comes off together. Each bracket has one full-size and three 3/4-inch penny-light positions; the pair takes two full-size and six penny lights, sold separately. The Peterbilt 589 A0030 pair is a separate model-specific product with the same air-cleaner geometry requirement and exclusions.

Interior plates: compare kit contents before adding parts

Both Peterbilt 389 kits below contain two above-door plates and one selected headliner plate. Each above-door plate has two full-size light positions. Choose a headliner for one full-size light or two 3/4-inch penny lights; switch count does not change that light layout. Compare the cab’s actual mounting points, trim and rear clearance before ordering.

Interior kit contents — scroll to compare all columns

Kit	Plates and switches	Choose separately
Peterbilt 389 dual-switch kit	Three main plates; two switches per plate, six total; listed screws and clips included	Lights and wiring
Peterbilt 389 single-switch kit	Three main plates; one switch per plate, three total; listed screws and clips included	Lights and wiring
Kenworth interior kit	Centre, driver-side and passenger-side main plates, plus two above-door mounting clip plates; no pre-cut switch holes	Lights, switches and wiring

Individual replacement plates are linked from each kit page. Check what the kit already supplies before adding separate plates or switches. The shared United Pacific 34274 above-door plate and 34026 eight-penny-light plate are different options: installing these plates requires headliner drilling or modification and bolting; they are not direct replacements.

Check panel size and package quantity

The A0021 front breather panels provide nine 1.25-inch LED positions per panel, eighteen per pair. The A0022 rear panels provide six per panel, twelve per pair. Check the listed air-cleaner and strap-bolt requirements and the exact lamp choices on those pages. These 1.25-inch lamp choices should not be confused with Mini watermelon lamps that mount through a 3/4-inch hole.

The A0031 fuel-tank bracket pair is a two-bracket setup for one side of the truck, with lights sold separately. Check the top-of-tank strap mounting position and the actual tank, step and surrounding clearances.

Alpha 360 mounting and control checks

Alpha 360 watermelon lights use a two-bolt flange and a shared ground with three separate mode power leads. Compare the mounting arrangement and rear clearance, then follow the exact light’s wire identification and installation instructions. Its rotating effect is an LED sequence, not a motor.

The lights are listed for 12V and 24V DC, but each control must also suit the supply. The optional Alpha Six Switch is listed for nominal 12V or 24V installations. The Diode Dynamics D-Switch requires 9–16V and is not a 24V panel. Match circuit loads, wiring and protection to both the light and the selected controller; the light generates its own modes. Alpha 360 is not DOT approved or a Class 1 warning light.

Questions before ordering

Does dual function always mean two colours?

No. The 34847 provides two brightness functions in amber. The 39231 has amber primary and blue secondary outputs, with the manufacturer’s restriction on secondary-colour use.

Is the lens colour the same as the illuminated colour?

Check both fields. The clear-lens 39231 produces amber or blue light; a clear lens does not mean white light.

Can I reuse my existing bracket?

Compare its measured mounting point and rear clearance with the selected lamp’s instructions. Similar appearance, a shared brand or the watermelon name alone does not establish compatibility.

Browse full-size watermelon lights, use the Full-Size Watermelon Light Guide to compare styles and components, or read Alpha 360 vs Glass Is Class Gen 2 for system-specific differences.

Fitment and specifications for the named examples were checked against United Pacific product documentation in September 2026. Always confirm the current product page and included parts before installation.