Hello again tarik

You will require a 120MVA transformer minimum for the Furnace operation.

Additional transformer capacity will be needed to run cranes, hoists, compressers, lighting and all extra apparatus, including cookhouse and/or housing for workers, which will be needed on or near the Site.

I cannot see your location, so have a look at (You will need to register at globalspecs): http://process-equipment.globalspec.com/SpecSearch/Suppliers/Manufacturing_Process_Equipment/Heating_Cooling_Equipment/Industrial_Furnaces?SrchItem=1&frmqry=Arc%20furnace&kqid=43628088

It would be normal to discuss your plans with the Electrical Engineer for your local Electric Supply Company, because they would need to make costly local alterations to their distribution network, before such a furnace of this type could be connected.

Kind Regards....

In most commercial and industrial installations, a dedicated transformer supplies each facility. Also, most of the equipment is running at the same time (coincident load). Therefore, the transformer is sized to supply the expected demand of a full operation, with all machines running together.

For residential service, one transformer supplies several homes. You and your neighbors will probably not all run your hairdryer at the same time, and your air conditioners will not all be running at the same time (non-coincident load). Even in an all-electric home, the thermostats for the oven, water heater, air conditioner and clothes dryer cycle on & off at various times while running, so the total demand is usually less than the sum of each unit demand. Because of the load variation, residential services are WAY oversized compared to actual usage. For example, the total demand for an electric range, an electric clothes dryer and a residential air conditioner, all running simultaneously, is less than 15 KVA. Since they don't all run together, peak demand is usually under 10 KVA. Your 225A service is good for 54 KVA at 240 volts.

The utility designs its equipment (generators, substations, lines, distribution transformers, etc.) to meet expected coincident peak demand, not connected service capacity. For commercial/industrial customers, the load factor (% of capacity in use) is much higher than residential, so the supply side must be built for more capacity.

The one time when the utility can get into trouble is during recovery from an outage. I was recently restored service to a 600-unit apartment complex after an extended outage on a cold night. All of the apartments have electric heat. As soon as the power was restored, all 600 heat pumps kicked on simultaneously. The demand was so high for the first 30 minutes I thought I still had a low-grade fault on the line!