Thanks everyone for the advice. It was invaluable in diagnosing the situation.
The owner thought that the whole relay was broken and wanted to replace it. It turned out it was a broken 12 year-old Schneider Connect wireless switch. It was actually a different relay (the one next to it) that was controlled by the wireless switch. I guess the original electrician installed a relay because even though there were just a few of these lights, they were in different parts of the premises and were wired across three phases. If the original installed had just ran the wiring through one more wall (there was already a hole) he could have installed an ordinary wall switch.
How long do these Schneider Connect switches usually last? The owner wanted to spend as little money as possible, so I recommended replacing it with a NEXA wireless switch (the 433MHz one-way system) but even the 35€ was above their budget so we re-routed the relay to be controlled by a specific control circuit breaker. They only use these lights once a week and wanted to use the circuit breaker as a switch instead of wiring a regular/wireless wall switch.
The funniest part is they tried to turn the power on by sticking a pen/pencil into the I 0 part of the relay to try turning it on. After everything started shaking they took the pencil out and understood that that was a bad idea!
The owner thought that the whole relay was broken and wanted to replace it. It turned out it was a broken 12 year-old Schneider Connect wireless switch. It was actually a different relay (the one next to it) that was controlled by the wireless switch. I guess the original electrician installed a relay because even though there were just a few of these lights, they were in different parts of the premises and were wired across three phases. If the original installed had just ran the wiring through one more wall (there was already a hole) he could have installed an ordinary wall switch.
How long do these Schneider Connect switches usually last? The owner wanted to spend as little money as possible, so I recommended replacing it with a NEXA wireless switch (the 433MHz one-way system) but even the 35€ was above their budget so we re-routed the relay to be controlled by a specific control circuit breaker. They only use these lights once a week and wanted to use the circuit breaker as a switch instead of wiring a regular/wireless wall switch.
The funniest part is they tried to turn the power on by sticking a pen/pencil into the I 0 part of the relay to try turning it on. After everything started shaking they took the pencil out and understood that that was a bad idea!