transfer switches

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arnold

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how many transfer switches would be needed for an emergency, legally required, and optional standby system in a hospital care facilities?
 

roger

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Retired Electrician
Re: transfer switches

Arnold see, Part III of 517. Note, in Health Care facilities the systems are addressed as the Essential Electrical System and is made up of the Emergency and Equipment Systems.

Notice the diagrams for the number of transfer switches.

The Emergency System is made up of the Critical and Life Safety Branches and would align with article 700 whereas the Equipment System would align with article 701.

Roger
 

roger

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Re: transfer switches

Arnold,
don't you need one for every system?
not necessarily, read 517.30(B)(4) and look at the FPN diagrams 1 and 2 as I mentioned. Do you have a code book?

Roger
 

roger

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Re: transfer switches

You are welcome.

Roger
 

d6183

Member
Re: transfer switches

based on 517-30-b-4 would you need one for every system as long as it was above 150kva what about 517-31 doesn't that combine life safety branch and critical branch or am i not reading that correctly?
 

roger

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Re: transfer switches

d6183,
Originally posted by d6183:
what about 517-31 doesn't that combine life safety branch and critical branch or am i not reading that correctly?
It only combines these Branches in the fact that they are both Emergency branches, They are still two completely seperate systems with different functions. See 517.32 and 517.33 for the specifics.

Roger
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Re: transfer switches

In general, for a large system (above 150KVA), you may need 4 transfer switches:
1. Life Safety Branch
2. Critical Branch
3. Equipment Branch
4. Optional or non-required loads

Steve
 
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