If there is a concern that 100amp supply isn't enough, I would be getting seriously concerned about the capacity to generate substantial electricity bills. 100Amps = 24KW at £0.229 per KWH thats bumping the bill by £5.49 per hour.
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As we are all electric, the safe max was a would be 28amp for the heating (not to sure why TBH) which would allow something like an 8KW heat pump, much more than that will require a 3 phase connection. Electricity prices here are pretty cheap 15.68 per KWh (at the moment) partially courtesy of not having to subsidise the green initiatives and partially because of good hedging of our French power supply.
