Pretty sure its 240 plus or minus 5%, and they won't actually try to fix it until its notably worse than that. This is 228-252V, so 249.8 is fine. On the bright side, motors work is easier at higher voltages.
Ah, you're right. I just looked it up. I'd just never seen a reported voltage that high.
Though come to think of it, at my house the UPS I have on my server and router usually shows 122-123 V so a 240V circuit would probably show up close to 246...not that far off.