Short of a malfunction of the eu2000i, there's no way to trip a GFCI hooked directly to its output. Because of the isolated output the short circuit current from either power output to case ground is below the GFCI trip threshold. The GFCI is required by some of the rules. On the eu2000i it's totally redundant and will never trip (without an internal malfunction). IMO a good deal for Honda having the bureaucracy force customers to pay $100+ for a GFCI outlet. I see the MSRP for the eu2000i is now 1149.95. That's an increase, isn't it?