Air-Conditioning can be considered as a “dirty” load due to continual switching causing voltage and current spikes and surges. The UPS module can cater for a certain level of overload for a small duration, however the duration and level of current surges typically associated with A/C units is far greater than the UPS’ capability. Therefore it is advised not to support the AC on a UPS and supply this element with a generator only if possible. If there is no option but to support the AC using a UPS, it is normal to oversize the inverter by 4-5 times to ensure that the unit will cater for this more demanding load and eliminate any risk to the critical load. Another sensible approach to reduce any risk is toeth critical load is to have a seperate dedicated UPS for the A/C requirement.