240V GFCI trips

[Gustavo001]

The electrical configuration: GFCI is in the main panel, non-fusible breaker located near spa. The GFCI is wired correctly (common from spa into the GFCI, pigtail into common bus bar). SPA is connected to the sub-panel. Sub-panel connects red, black and ground together, common is wired with wire nut.
The spa operated properly initially for 10 minutes. The GFCI tripped and now trips immediately.

 

[ajw22]

Welcome to TFP.

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You asked about a spa but posted in the above ground pool section so not sure what type of setup we are discussing.

What is on that circuit?

If the problem is with a spa GFCI trips are often caused by water leakage into the heater electrical system. You need to follow a process of elimination and disconnect the pump(s) or heater to determine which is causing the trip.