Panel MCB sizing for (2) CT machines and (2) Xray machines

[CXC0987]

Sizing a panel for (2) CT machines and (2) Xray machines, NEC 660.6 states that the ampacity of supply branch-circuit conductors and the overcurrent protective devices shall not be less than 50 percent of the momentary rating or 100 percent of the long-time rating, whichever is greater.

this apply to X-ray machine but does that also apply to CT scanning machine? I don't there is any code section in NEC or NFPA 99 talking about CR machine demand power calculation.

 

[LarryFine]

Welcome to the forum.

Do CT scanners have similar momentary/long-time operating characteristics?

If not, then use the long-time current like you would with most loads.

 

[CXC0987]

Hi Larry, thanks for the response, appreciated
the CT almost has 3 times the momentary KVA than the xray.
I am dealing with Siemens CT machines, and their site-specific gives you a chart showing the KVA consumption when CT operates at 2 sec, 35 sec, and 100 sec (350kva, 130kva, and 87kva).
Not too sure if I should use KVA rating at 35sec or 100sec which really depends on the definition of long-time current.