derating multiple trefoils

IMHO, it also depends a bit on the location.

In a warm climate I would adopt a conservative approach. Remember that the outside air may regularly reach 30 degrees, and that 40 degrees is likely in well ventilated switchroom or substation. Peak loads will tend to be in the hottest weather and might tend to exceed the design figures.

In the UK I might push the cables a little harder, to the manufactures ratings when these exceed other guidelines. Outside air in the UK seldom reaches 30 degrees, and moreover peak loads tend to be in the colder weather.

There is a lot of difference between say 2,000 amps in a heatwave with 40 degrees ambient and the same 2,000 amps on a cold winter day at around freezing point.

Finally with energy prices increasing, one should consider not just "how many amps can the cables carry" but also what is the annual cost of the cable losses. Reducing the losses by use of larger or more numerous cables may be worthwhile.

Saving about one volt at these sort of currents can amount to as much as 10kw. At current UK prices that is about £5 an hour. For a long hour load that could be in the region of £25,000 a year.

IMHO, it also depends a bit on the location.

In a warm climate I would adopt a conservative approach. Remember that the outside air may regularly reach 30 degrees, and that 40 degrees is likely in well ventilated switchroom or substation. Peak loads will tend to be in the hottest weather and might tend to exceed the design figures.

In the UK I might push the cables a little harder, to the manufactures ratings when these exceed other guidelines. Outside air in the UK seldom reaches 30 degrees, and moreover peak loads tend to be in the colder weather.

There is a lot of difference between say 2,000 amps in a heatwave with 40 degrees ambient and the same 2,000 amps on a cold winter day at around freezing point.

Finally with energy prices increasing, one should consider not just "how many amps can the cables carry" but also what is the annual cost of the cable losses. Reducing the losses by use of larger or more numerous cables may be worthwhile.

Saving about one volt at these sort of currents can amount to as much as 10kw. At current UK prices that is about £5 an hour. For a long hour load that could be in the region of £25,000 a year.