This is a tricky one, and the fact that you've consulted so many people without a solution suggests it's something unusual. Let's break down the possibilities and think outside the box. Here's a structured approach to troubleshoot this

1. Reiterate and Confirm the Basics (Even Though You Think You Have):
Driver Compatibility (CRITICAL)

You say the drivers are rated for 0-10V dimming. Specifically verify that they are compatible with the type of 0-10V dimming signal produced by your dimmers. Some dimmers source current, others sink it. If the driver isn't expecting the type of signal your dimmer is producing, weird things can happen.

Get the EXACT model numbers of both the dimmers AND the LED drivers and confirm compatibility in their specification sheets. This is the most common cause of problems with 0-10V dimming. Voltage Rating Confirmation

Triple-check that both the dimmers and the LED drivers are genuinely rated for 277V. A mismatch here could cause the behavior you're seeing.

Wiring Configuration

Double-check your wiring diagram and ensure you haven't accidentally crossed any wires. Pay special attention to the neutral and ground connections. Even if it's worked before, a slight miswiring could be the issue here.

Solid Neutral Connection

A poor or missing neutral connection is often the culprit of weird voltage issues. Ensure your neutral is properly bonded back to the panel.

2. Deep Dive into the Dimmer's Off-State Behavior



Leakage Current/Voltage

Some solid-state dimmers, even when "off," allow a small leakage current or voltage to pass through. This is normal, but usually very low. 100V is excessive. Look for the dimmer manufacturer’s documentation on leakage voltage in the off state. A value for leakage current may also be provided.

Dimmer Design

Determine whether the dimmer is designed to act as a true open when off, or whether it includes a small resistance that permits a residual voltage to pass through.

3. Isolating the Problem



Single Fixture Test

Disconnect all but one LED panel and dimmer from the circuit. See if the issue persists. If it goes away, it suggests an interaction between multiple panels or dimmers is the root cause.

Different Brand/Model

Try a different brand or model of 0-10V dimmer. If the problem disappears, you've likely found a compatibility issue with the original dimmers.

Control Wiring

If the dimming control wiring is bundled with power conductors, try separating them to rule out the possibility of noise or interference on the control line.

Grounding

Check the grounding on each fixture to ensure it is connected to the ground wire of the circuit with the correct gauge wire.

4. Investigate the Load (LED Panels/Drivers)



Driver Input Impedance

0-10V dimming drivers have a certain input impedance on their dimming control wires. It's possible your dimmers are not designed to work with that impedance, especially with multiple drivers in parallel. Check the driver's specification sheet for input impedance on the dimming control wires, and compare that against the dimmer's output specification.

Driver Current Source/Sink

As stated above, 0-10V dimmers either source or sink current. You need to match these. The driver specification will state whether it sources or sinks current.

Driver Compatibility

The problem might not be the dimmer itself, but some characteristic of the LED driver causing it to backfeed or induce a voltage on the dimming circuit, even when "off." Replace ONE of the 2x4 panels with a different brand/model to see if the problem goes away.

Driver Failure Mode

While less likely, a failing LED driver could be causing the issue. A short or internal fault within the driver could be injecting voltage onto the dimming wires.

5. Look for External Influences



Nearby Electrical Equipment

Is there any other high-voltage or high-current equipment nearby that could be inducing a voltage on the wiring? (e.g., large motors, transformers, other lighting circuits).

Wiring Proximity

Check for parallel runs of high-voltage and low-voltage wiring. Inductive coupling can occur, particularly over long distances.

6. Advanced Troubleshooting (If Nothing Else Works)



Oscilloscope

If you have access to an oscilloscope, use it to examine the voltage waveform on the switch leg and the 0-10V dimming wires. This might reveal transient voltages, noise, or other anomalies that are not visible with a standard multimeter.

Insulation Resistance Testing

Perform an insulation resistance test on the wiring from the dimmer to the LED panel. This can help identify any insulation breakdown that might be allowing voltage leakage.

Important Considerations



Safety

Work on electrical systems only if you are qualified and trained. Disconnect power before working on any wiring. If you're not comfortable with high-voltage electrical work, hire a qualified electrician.

Documentation

Keep detailed records of all your testing and troubleshooting steps. This will help you track your progress and identify patterns.

Specific questions to ask the manufacturers



Dimmer Manufacturer

"Under what conditions does your dimmer allow a voltage to pass through to the switch leg when in the OFF position? What is the specified leakage voltage and current?"

LED Driver Manufacturer: "What is the input impedance of the 0-10V dimming control wires? What is the required source or sink current?"Good luck! This is definitely a puzzle, but by systematically eliminating possibilities, you should be able to find the cause. Please share your findings when you solve the problem, it will help others in the future. Flag for review