LIM Panels (Again)

[SparksRfun]

Operating rooms typically use Line Isolation Monitor (LIM) panels for power because they are wet locations. I am working in an operating room that is definitely so, the nurses tell me it is routinely wet during procedures. It has a single LIM panel on critical branch power. They've outgrown the panel, because they have mulioutlet strips and cords running all over the place. a couple of the suites have been upgraded with a second LIM panel.

NEC 517.19(A) says that each patient BED location shall be supplied by one or more normal circuits and one or more emergency circuits. I don't think a surgery suite is a patient "Bed" location however the priciple is to give more reliability than just one source of power.

NFPA 99 4.3.2.2.1 (B)Critical Care Areas says that "These areas" shall have some emergency and some normal power or "a system originating form a second critical branch transfer switch."

Would it be better to have two LIM panels in an operating room, one on critical branch and one on normal branch power, or two LIMs both on critical branch power originating from separate transfer switches?

 

[davidbeach]

Two transfer switches.

 

[SparksRfun]

>Two transfer switches.
Thanks!

And your reasoning would be?

Any codes that say you CAN'T do this?

 

[davidbeach]

The point is looking for reliability. The requirement for a second source is that transfer switches are generally the weak link, so for a failure of the transfer switch you could still have power from the normal source. Better would be two sources from different transfer switches so that if there were a transfer switch failure associated with a loss of utility power (as likely a time for a transfer switch failure as any) and the other transfer switch could supply the load.