(13 Nov 2021, 11:06 am)Dan wrote Agreed. It all boils down to Health & Safety requirements. Drivers have to manually turn the 240V sockets on, and if one fuses, it knocks them all off. Given the lower voltage, the USBs can be turned on by default (with an option to turn off, the opposite of the 240V sockets) and unlike the 240V sockets they're not all linked on a circuit so if one goes off the rest aren't affected (from what I understand, with limited electrical knowledge!)

The sockets on the Volvo B9s always used to work (as a semi-regular user of the 56 when the B9s replaced the L94s) and were supposed to be checked again when they first got repainted/refurbished. I noticed a couple of years ago that Arriva started to replace some of their 240v three-pin sockets with USBs, but didn't ever seem to finish them.