Yes, there can be a shock hazard with a properly functioning power supply without a green (ground/earth) wire, even if the power supply seems to be functioning correctly under normal circumstances.Here's a breakdown of why the green wire is crucial and why the person's experience makes sense

Why the Green Wire (Ground/Earth) is Essential for Safety
Fault Current Path

The primary purpose of the green wire is to provide a low-resistance path back to the electrical panel in case of a fault within the power supply. A fault is when a live (hot) wire comes into contact with the metal chassis or casing of the power supply.

Circuit Breaker Tripping

Without the green wire, a fault current might not be high enough to immediately trip the circuit breaker. This means the metal casing of the power supply could become energized (hot) and pose a severe shock hazard to anyone who touches it. The green wire ensures a large enough current flows in a fault situation to rapidly trip the breaker, cutting off the power.

Lowering Touch Potential

Even a small amount of leakage current from the power supply can build up on the metal enclosure without a ground connection. The green wire bleeds off this stray voltage, preventing a dangerous "touch potential" (voltage difference between the enclosure and the person touching it) from developing.

Safety Standards

Many power supplies, especially those used in permanent installations, are designed with a metal enclosure and are required to have a ground connection to meet safety standards (UL, CE, etc.). These standards are in place to prevent electrical shock.

Why It Might Seem to Work Without the Green Wire (Until a Problem Occurs) Normal Operation

Under normal operation, the power supply might appear to function perfectly well without the green wire. The LED strip might light up, and everything might seem fine. This is deceptive.



The Problem is Latent

The shock hazard exists only when a fault condition occurs. This is why the person likely only noticed the problem after some manipulation or accidental event that created a fault.

Why the Person's Experience Makes SenseThe fact that the LED strip only worked after connecting the green wire strongly suggests one or more of the following:1.

Faulty Power Supply

The power supply might have an internal fault that was causing a small leakage current or voltage to build up on the metal casing. Without the ground, this leakage current was disrupting the proper operation of the LED driver circuitry. When the ground was connected, it provided a path for that leakage, allowing the power supply to function as designed (though it should be replaced due to the internal fault).2.

Induced Voltage

There might have been a static build up that was not able to dissipate until a proper bonding conductor. The green wire gives a path for the voltage to follow to ground.

Conclusion

Never omit the green wire on a power supply that is designed to have one. It is a critical safety component.

If the power supply requires a ground connection (the manufacturer designed it with a green wire terminal or attached green wire), it's unsafe to operate it without that connection.

If a power supply only functions correctly with the ground wire connected, it's a sign that the power supply itself may be faulty and should be inspected or replaced. The ground wire should be a backup safety measure, not a primary component required for correct operation.

In summary: Yes, there is a shock hazard with a properly functioning power supply without a green bond wire in a fault situation, even if the device appears to be working normally.* The person who experienced the issue likely had a power supply with a pre-existing (perhaps minor) fault, and the ground wire provided the necessary path to either bleed off the leakage or enable the device to operate despite the fault (but still dangerously). Flag for review