ESD protection for RS485 with power bus, without earth
Don‘t get tricked into thinking you can control where some voltage or current spikes will flow and where not.
Usually, the ultimate goal of ESD protection is to ensure that the victim (IC) will never get more voltage than it can take.
So your design goal of ESD protection is to use protection devices to kind of clamp all signals, GND and VCC together. So if e.g. GND suddenly  goes below -2000V, the other lines must follow. Think of the sensitive IC being sandwiched between protection devices.
Further advice: L is useless or even bad. Place the TVS between 24V and GND (explanation above).