Synergistic Research Black fuese

I'm in the UK, and I'm going to order some of the new SR Blue Fuses, I need 315mA for my Nagra CDP, PSU - ACPS-II 230V, but some say use a slightly larger fuse like your previous posts.

The next fuse up is the 500mA, would it be okay to use the 500mA instead of the 315mA on my Nagra CDP, my CDP is plugged iny my Isotek Nova that as the RCD trip switch protection.

In thinking about my question above, I'm safer sticking with the original 315mA, as here in the UK the voltage is around anywhere from 230V to up to around 250V, so the 500mA is 59% higher rating than the 315mA, i.e too high for our voltage, so the 20% to around the 25% margin really only applies to 115V. So here in the UK we are probably better sticking to the original fuse rating.