Volts to amps sits behind every cable sizing, breaker selection and fault current decision on a commercial site. A new 22 kW EV charger on a 400 V three-phase supply draws around 32 amps per phase at full output. A 50 kW rooftop air-source heat pump on the same supply draws closer to 75 amps. A 250 kVA standby gen-set delivers about 360 amps per phase. Each figure drives a different cable cross-section, a different breaker rating, and a different position on the discrimination ladder. Getting the conversion wrong at design stage propagates through every downstream choice on the panel schedule.
Fault current estimation is the other regular use of the volts to amps maths. The prospective short-circuit current at a distribution board sets the minimum breaking capacity of the protective devices, and it varies sharply with the impedance of the upstream transformer and the cable run back to it. Boards specified against an outdated fault level (the supply infrastructure on UK industrial estates has been quietly upgraded over the last decade) routinely sit underspecified for the actual prospective fault current. A periodic review of the volts to amps figures at the head of the site, against current DNO data, is a worthwhile insurance policy.
Purely Energy works on the procurement and bill side of these projects rather than the panel side, but the cable sizing question is the first place a CFO sees a six-figure capex line on an electrification programme. A clean volts to amps conversion, applied across the new loads being added (EV fleet, heat pump heating, induction kitchens, battery storage), gives a defensible feeder size and a defensible MIC requirement. Both numbers then feed straight into the DNO conversation, the connection cost, and the supply contract structure. Use this tool as the engineering reference; talk to us when the contract gets re-priced.