You use the correct size breaker that matches the wiring. The correct amperage will be listed in the owners manual for the tub.
This size service can be wired in a few combinations. Two parallel runs of 1250 MCM, three parallel runs of 600 MCM, four parallel runs of 350 MCM. Of the three choices the four runs of 350 MCM wires would be the easiest to handle if there are any bends in the service entrance conduit.
There are different combination to obtain a current capacity of 1250 amps. A parallel run of #1250 MCM wires. A triple run of #600 MCM wire. The most flexible run would be with a quad run of #350 MCM wire.
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Answer for USA, Canada and countries running a 60 Hz supply service.The answer is 3/0 copper or 250 kcmil aluminum and requires that the METAL water pipe have at least 10ft of its length in direct contact with the earth. Using a METAL water pipe as a grounding electrode also requires a supplemental electrode, which is most commonly one or more ground rods.This is NOT the way most 600A services are grounded and I recommend you consult a licensed electrician in your area to determine what is commonly done in your area.As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.Before you do any work yourself,on electrical circuits, equipment or appliances,always use a test meter to ensure the circuit is, in fact, de-energized.IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS.
Conductors by code are only allowed to be loaded up to 80 percent. In this case an over size wire set will be higher that what the wire is rated for in the code book. A 600 MCM copper conductor with an insulation factor of 90 degrees C is rated at 455 amps. Paralleled together will give an ampacity of 910 amps. After the derate the maximum amperage allowed is 728 amps. So to get the full 900 amp the wire size has to be increased to a 1000 MCM copper conductor with an insulation factor of 90 degrees C which is rated at 585 amps. Paralleled this give you an ampacity of 1170 amps. After the derate the maximum amperage allowed is 1170 x 80% = 936 amps
3% of 1250 = 3% * 1250 = 0.03 * 1250 = 37.5
1250 + 8% = 1250 + 100 = 1350 or 1250 + 8%.
You should work it out in your head or on a calculator but its 1250
15% off of 1250 = 1250 - (0.15 x 1250) = 1062.5
1250 to fraction = 1250/1
percentage of 1250 = 125000%1250 * 100% = 125000%
10% off of 1250 = 90% of 1250 = 1250*90/100 = 1125
38% of 1250 yards= 38% * 1250= 0.38 * 1250= 475 yards
4% of 1250 = 4*1250/100 = 50
90% of 1250 = 1250*90/100 = 1125
250% of 1250 = 1250*250/100 = 3125
1250 is a whole number.1250/1 in fraction