Okay, let's break down the best way to approach your undercabinet lighting project, keeping efficiency, future-proofing, and your client's requirements in mind.

The Core Problem: Multiple Switches, Single Driver Desired

Your instinct to avoid three separate drivers is correct. It's less efficient, more wiring, and generally less elegant. The key is to find a driver and wiring scheme that accommodates multiple switches while allowing for potential future dimming.

Recommended Approach: Single Driver with 3-Way Switching (Modified)

This approach leverages the principle of a 3-way switch but adapts it to switch the low-voltage side of the LED driver, not the high-voltage line voltage. This is safer and makes future dimming much easier.

Here's the breakdown


Choose a Dimmable Driver (Even if Not Immediately Used)

Seriously. It's a small extra cost now, but massively simplifies adding dimming later. Select a driver that: Has sufficient wattage for all the undercabinet lights on all three sections COMBINED. Calculate the total wattage requirement by summing the wattage of each LED strip you plan to use (length x watts per foot).

Over-spec it by 20%. You don't want the driver running at its maximum capacity constantly. Is 24VDC output (as you mentioned). This is a common and safe voltage for LED strips. Is 0-10V dimmable. This is an industry-standard dimming protocol, and almost all LED dimmers and smart home systems support it. Has UL (or equivalent) safety certification.2. Wiring Scheme (Simplified Three-Way on Low-Voltage Side)



Driver Placement

Find a central location for the driver (e.g., above the cabinets, in a nearby closet) that is easily accessible for future maintenance.

Power to Driver

Run a standard 120V line to the driver location.

Low-Voltage Distribution (24VDC)

From the driver's 24V+ output, run a cable (appropriate gauge for the current load - see below) to each switch location. Connect this wire to the common terminal of each switch. From each switch's other terminal (there should be one remaining terminal), run a wire to the corresponding section of undercabinet lights. Connect this to the 24V+ input of the LED strips. Run a single, common ground (24V-) wire from the driver's 24V- output to all the LED strips, connecting to their 24V- input. This is your negative bus.

Diagram

[120V AC] --> [LED Driver (24VDC)]|+---[24V+]---> Switch 1 (Common) ----> Undercabinet Lights 1 (+)|       |+---[24V+]---> Switch 2 (Common) ----> Undercabinet Lights 2 (+)|       |+---[24V+]---> Switch 3 (Common) ----> Undercabinet Lights 3 (+)|+---[24V-]---------------------> Undercabinet Lights 1, 2, 3 (-) (Common)

Explanation

Each switch simply completes the 24V+ circuit to its section of lights. When the switch is flipped on, the 24V+ flows from the driver, through the switch, to the lights. The common negative wire provides a continuous return path for the current.3.

Wire Gauge Calculation

This is critical. Undersized wiring can cause voltage drop, heat, and even fire. Use a wire gauge calculator to determine the appropriate wire size. Factors to consider:

Total Current Draw

Add up the current draw of all the lights on all three sections (wattage / voltage = amps).

Voltage Drop

Aim for a voltage drop of no more than 3% on the 24V circuit. This affects light output and LED lifespan.

Wire Length

Measure the longest wire run from the driver to the furthest light section. Longer runs require thicker wire.

Online calculators are your friend. Search for "wire gauge calculator voltage drop."4. Future Dimming



0-10V Dimming

If the client decides to add dimming later, you've already chosen a compatible driver.

Wiring

Run a shielded twisted-pair cable (two conductors) from the driver location to a convenient spot for a dimmer (e.g., near one of the switches, or a central location).

Dimmer Installation

Connect the 0-10V dimmer to the driver (according to the dimmer's instructions). The dimmer will then control the output voltage of the driver, dimming all the lights proportionally.

Important Considerations



Safety

Always disconnect power before working on electrical wiring. Consult with a qualified electrician if you are unsure about any aspect of this project.

Local Codes

Ensure your wiring complies with all local electrical codes. This often requires using specific types of cable (e.g., CL2 or CL3 rated for in-wall installation).

LED Compatibility

Make sure the LED strips you choose are designed for 24VDC operation and are compatible with dimmable drivers (if you're future-proofing).

Switch Type

Use standard single-pole switches for this setup.

Why This is Better



Efficiency

Single driver is more efficient and cheaper.

Future-Proofing

The dimmable driver and extra wiring make adding dimming later simple and cost-effective.

Simplicity

The wiring is relatively straightforward, adapting a well-known principle (3-way switching) to the low-voltage side.

Safety

Switching low-voltage is inherently safer than switching high-voltage.

Control

Provides the individual control the client wants.

Alternative: Smart Home Integration

If the client is open to it, consider a smart home system. You could use a single driver and smart switches (e.g., Z-Wave, Zigbee, Wi-Fi) that communicate wirelessly to control the lights. This offers even more flexibility and control options, including dimming, scheduling, and voice control.

In summary, go with a single, appropriately sized, dimmable (0-10V) driver, and use the modified 3-way wiring scheme on the 24VDC side. Remember to calculate your wire gauge carefully, and plan for future dimming by running the extra control wires. Good luck with your project! Flag for review