I want to run 2/3 tumble dryers where there's currently a single outlet

The previous poster has provided some good information, although I would also ascertain that the existing socket outlet is supplied from the ring final; it may be likely that it is repurposed from an obsolete immersion radial circuit. It should also be noted however that BS1363 (for 13A outlets) stipulates that a single outlet is rated at 13A (2990w), and a double at only 20A (4600w), and not 26A as is the common misconception. It is quite common for manufacturers to reduce this further to only 13A per outlet. This should therefore be taken into consideration when designing any new circuits. I would engage the advice of a competent contractor to assess fully. Kind regards Ben

7360 watts thats your total wattage on a standard ring circuit ran in 2.5mm twin and earth flat cable, and current overload protected by a 32 amp MCB , this is common in almost every home in the UK. for 3 tumble dryers on full you could be reaching 750 watts ! I would run another dedicated (Radial 32amp circuit, this will also give you 7360 watts) from your existing consumer unit in 4mm Twin and Earth to 2 single 13a Socket outlets this will cover 2 tumbles at full capacity and the other I would keep on the existing socket you have. Do not forget RCD protection would need to be installed and your Gas / Water Earth bonding would also need to be installed in 10mm single earth if not already in place. and the new circuit would require a full electrical certificate not a minor works .. happy drying - Chase Electrical