Life Support Branch

I can see where they no longer want separate systems where half the outlets are generator backed and the rest aren't but now want everything generator backed to prevent the headache, hassle, and possible deaths of trying to get everything moved onto the backed-up outlets every time there's a hiccup. Building a hospital I'd state "everything is important" back it all up. Then direct the management to conserve where possible as needed.

Keith Cress
kcress -

Now you've got me wondering- who is they? NFPA 99 still allows for half and half.

By "They" I mean corporations or entities building hospitals.

I can easily envision over taxed hospital staff plugging life safety equipment into remaining available outlets that aren't backed up. Power fails and patients get injured or die specifically because someone plugged something they shouldn't have into a non-backed outlet. Lawsuits occur and insurers get hit over and over for the same exact events. I can see this blowing back into NFPA's face when the insurance companies figure out that half-and-half systems ordained by NFPA are killing people.

Half and half systems require an entire other layer of attention in a field nurses and doctors aren't informed about. Orange/white outlet games don't make sense when for an incremental increase in back-up power you can completely remove the requirement, hazard, and exposure.

Keith Cress
kcress -

@Itsmoked: Well written, and being honest I agree 100%. I never agreed with the half and half approach. In fact was stunned when I first saw it in practice. You are already required to have two branches and multiple circuits per bed and OR. An extra ATS sots next to nothing considering you went to all the trouble already of having redundant power.

It's the same problem with one's own house. They trot out those separate breaker panels and try to pick/guess which house circuits should be backed-up. It's a lame game that always leaves something important left out. Perhaps that dark treacherous stairway light or the newly installed sump pump, the internet router, etc. It's much better to just setup the whole place on a transfer switch or a simple interlocked breaker. The user can then use what they need when they need it keeping what they don't need off.

I always hated it when I had to switch to generator and went to all the hassle to get it started, on line, and cords everywhere and the refer pulled into the middle of the kitchen so the plug could be shifted to the generator extension cord only to have the power come back. It was extremely frustrating - curse-worthy. LOL

Keith Cress
kcress -

I feel your pain. A while back I had to put the furnace at my old house on a cord. Kept loosing power during the winter.

But anyways, the reason why I ask.

The NEC from the 70s had an allowance for a life support branch in addition to the critical branch- and the fact a fair share of pre 80s hospitals actually had a dedicated life support branch in conjunction with a separate critical branch.

From the 1971 NEC:




Graphic in the ROPs:



It is interesting to note that the CMPs originally agreed that the life support branch could be combined with the life safety branch if they were not separate.

1971 ROP:



The life support branch was originally intended to receive the same fire protection and priority as the life safety branch which was (and still mostly is today) required to meet the requirements of article 700.

Latter on the CMPs changed their minds that the life support branch could be combined with critical branch instead of the life safety branch.

For the 1978 NEC a proposal was sent in to delete the concept of a life support branch:





Accepting the proposal was a fantastic impulse without any thought and hare-brained to be frank.

It took away the concept of a protected high priority branch that not only should/would have followed article 700 but also the greater probability of getting rid of the half and half approach in ORs and ICUs during design.

Hospitals work on the concept of compartmentalization, isolation and segregation to deal with fires. Evacuation of a whole hospital building is not possible or practical.

The requirements of 700 force the life safety branch to be protected from fire and in separate electrical rooms segregated from all the other branches in a hospital.

Yet the critical branch and normal branch are often in the same room without any fire protection be it in the shafts, interstitials, ceilings, partitions, walls, ect.

This wholly contradicts the compartmentalization approach to hospitals.

How the NFPA doesn't see this is beyond me, unless people incapable of self preservation (from being ill or different) are seen as lesser priority than those who are able bodied- which is not out of the realm of possible given history...

Hospitals outside of North America have a dedicated, protected life support branch in addition to a normal and critical branch.

North American hospitals for the last 50 years have been designed and built missing a life support branch.

How it translates into the real world- as typical:

(Black = Normal, Green = Critical, Blue = Equipment, Red = Life Safety)



Going up the building.



Life safety is concrete encased, in a dedicated segment of the building's core, run as individual circuit feeders (events above can not remove circuits below), branch circuits covered in fire proofing run flush with columns or floor diaphragms above the sprinkler line, and panels are in separate electrical closets.

Normal and critical on the other hand are run as exposed bus duct in the same electrical room. Branch circuits are without reservation and unprotected. No fire protection or physical segregation- code does not require it.

A fire or catastrophic failure of the normal electrical system can remove both critical and normal power.

Normal and Critical bus duct within inches of each other: