demand factor for hospital diagnostic machines

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jaraujo1

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I reviewed 517.73 (A) ad (B) - Rating of Supply Conductors and Overcurrent Protection.

It is not clear to me if there is any demand load factor that may apply that will affect the overall sizing of the feeder and incoming services when there is an X-ray, MRI and CT-Scan in different circuit branches.

Happy New year to all and God be with you!!!

Any feedback is appreciated.
 
jaraujo1 said:
I reviewed 517.73 (A) ad (B) - Rating of Supply Conductors and Overcurrent Protection.

It is not clear to me if there is any demand load factor that may apply that will affect the overall sizing of the feeder and incoming services when there is an X-ray, MRI and CT-Scan in different circuit branches.

Happy New year to all and God be with you!!!

Any feedback is appreciated.
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I thought this below rule is clear enough?

517.73 (A)(2) Feeders. The ampacity of supply feeders and the current rating of overcurrent protective devices supplying two or more branch circuits supplying X-ray units shall not be less than 50 percent of the momentary demand rating of the largest unit plus 25 percent of the momentary demand rating of the next largest unit plus 10 percent of the momentary demand rating of each additional unit. Where simultaneous biplane examinations are undertaken with the X-ray units, the supply conductors and overcurrent protective devices shall be 100 percent of the momentary demand rating of each X-ray unit.

FPN: The minimum conductor size for branch and feeder circuits is also governed by voltage regulation requirements. For a specific installation, the manufacturer usually specifies minimum distribution transformer and conductor sizes, rating of disconnecting means, and overcurrent protection.
 
jaraujo1 said:
I was asking for feedback to determine if the the demand factor applies when you have more than one machine.
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Why can't you apply demand factor as described in 517.73.A(2)? Can you be more specific?
 
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